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Provider volume and maternal complications after Caesarean section: results from a population-based study


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Background: A large literature search suggests a relationship between hospital/surgeon caseload volume and surgical complications. In this study, we describe associations between post-operative maternal complications following Caesarean section and provider caseload volume, provider years since graduation, and provider specialization, while adjusting for hospital volumes and patient characteristics. Methods: Our analysis is based on population-based discharge abstract data for the period of April 2004 to March 2014, linked to patient and physician universal coverage registry data. We consider all hospital admissions (N = 20,914) in New Brunswick, Canada, where a Caesarean Section surgery was recorded, as identified by a Canadian Classification of Health Intervention code of 5.MD.60.XX. We ran logistic regression models to identify the odds of occurrence of post-surgical complications during the hospital stay. Results: Roughly 2.6% of admissions had at least one of the following groups of complications: disseminated intravascular coagulation, postpartum sepsis, postpartum hemorrhage, and postpartum infection. The likelihood of complication was negatively associated with provider volume and provider years of experience, and positively associated with having a specialization other than maternal-fetal medicine or obstetrics and gynecology. Conclusions: Our results suggest that measures of physician training and experience are associated with the likelihood of Caesarean Section complications. In the context of a rural province deciding on the number of rural hospitals to keep open, this suggests a trade off between the benefits of increased volume versus the increased travel time for patients.
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R E S E A R C H A R T I C L E Open Access
Provider volume and maternal
complications after Caesarean section:
results from a population-based study
Philip S. J. Leonard
, Dan L. Crouse
, Jonathan G. Boudreau
, Neeru Gupta
and James T. McDonald
Background: A large literature search suggests a relationship between hospital/surgeon caseload volume and
surgical complications. In this study, we describe associations between post-operative maternal complications
following Caesarean section and provider caseload volume, provider years since graduation, and provider
specialization, while adjusting for hospital volumes and patient characteristics.
Methods: Our analysis is based on population-based discharge abstract data for the period of April 2004 to March
2014, linked to patient and physician universal coverage registry data. We consider all hospital admissions (N= 20,914)
in New Brunswick, Canada, where a Caesarean Section surgery was recorded, as identified by a Canadian Classification
of Health Intervention code of 5.MD.60.XX. We ran logistic regression models to identify the odds of occurrence of
post-surgical complications during the hospital stay.
Results: Roughly 2.6% of admissions had at least one of the following groups of complications: disseminated
intravascular coagulation, postpartum sepsis, postpartum hemorrhage, and postpartum infection. The likelihood of
complication was negatively associated with provider volume and provider years of experience, and positively
associated with having a specialization other than maternal-fetal medicine or obstetrics and gynecology.
Conclusions: Our results suggest that measures of physician training and experience are associated with the likelihood
of Caesarean Section complications. In the context of a rural province deciding on the number of rural hospitals to
keep open, this suggests a trade off between the benefits of increased volume versus the increased travel time for
Keywords: Caesarean section, Postoperative complications, Epidemiological research design, Maternal health
A large volume of literature has established that for
some procedures, higher hospital and/or higher phys-
ician surgical volumes are associated with lower postop-
erative mortality or other adverse outcomes [13]. By
comparison, the volume-outcome relationship is less
well-established for Caesarean section surgeries (hence-
forth C-Sections). Of the research examining the rela-
tionship between physician characteristics and C-
Sections, much of the focus is on the likelihood that a
C-Section was performed (that is, instead of a vaginal
delivery) [410].
A few international studies have reported a negative
relationship between the likelihood of postoperative C-
Section complications and years of surgeon experience
[11,12] and the surgeons C-Section volume [13]. On
the other hand, neither the surgeons training level nor
the surgeons case volume were found to be significant
predictors of utero-cervical lacerations or blood loss in a
study of anesthesia-related complications after C-
Sections in New York State [14]. There is some evidence
that the level of service at a hospital plays a role, with
large variations in the probability of complications
across US hospitals [15] and evidence that rural Canad-
ian hospitals have poorer outcomes compared to larger
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( applies to the data made available in this article, unless otherwise stated.
* Correspondence:
Department of Economics, University of New Brunswick, Singer Hall, Room
459, P.O. Box 4400, Fredericton, New Brunswick E3B 5A3, Canada
New Brunswick Institute for Research, Data, and Training, University of New
Brunswick, Fredericton, New Brunswick, Canada
Full list of author information is available at the end of the article
Leonard et al. BMC Pregnancy and Childbirth (2020) 20:37
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ones [16]. There are very few studies of C-Section out-
comes that adjust simultaneously for physician and hos-
pital volume, and to our knowledge, none using
Canadian data.
In this study, we aim to help fill this information gap
by measuring associations between post-operative C-
Section complications and physician and hospital char-
acteristics at a population level. Echoing the trend in in-
creasing C-Section rates worldwide, surgical deliveries
have risen steadily in New Brunswick, Canada in recent
years, currently representing 4.9% of all inpatient surger-
ies [17]. Our objective is to determine what factors are
related to any observed volume-outcome relationships,
that is, specific characteristics of the hospitals or physi-
cians themselves, adjusting for measures of obstetric
risk. We use a binary outcome variable coded as 1 if the
mother suffers from any of four types of complications
during her hospital stay. We use a population-based
dataset of hospital discharge records from the province
of New Brunswick. Due to Canadas universal single-
payer healthcare system that covers all physician and
hospital services for residents, these data are considered
population representative and complete.
The New Brunswick context is one of a relatively large
rural population (48% rural compared to a national aver-
age of 19%, according to 2011 census data [18]), declin-
ing fertility (below-replacement total fertility rate of 1.60
in 2014 [19]), and low population density (10.5 residents
per square kilometre [18]). There are currently 13 hospi-
tals where women can give birth in the province. Few
give birth outside the medicalized system [20]. For the
province as a whole, approximately 27% of births in
2012 were via C-Section, and the primary C-Section rate
is approximately 19% [21]. Ongoing debates on health-
care reform often raise the issue of closing smaller local
hospital facilities in favour of larger regional hospitals
(i.e. regionalization or centralization) due to the sugges-
tion that quality of surgical outcomes may improve be-
cause of increased experience of surgeons and their
teams. This research aims to strengthen the evidence
base to inform health policy decisions.
This study was approved by the University of New
Brunswick (UNB) Research Ethics Board (REB file 2015
106). The analysis was conducted at the New Brunswick
Institute for Research, Data and Training (NB-IRDT), a
research institute on the UNB campus that provides ap-
proved researchers with secure access to de-identified
health-related and other administrative databases. Our
retrospective population-based analysis is based on Dis-
charge Abstract Database (DAD) records, which have
been linked to Provider Registry Data (for physician
characteristics) and to Citizen Registry data (to
determine patient characteristics including age, sex and
six-digit residential postal code). Postal code information
was further matched to Statistics Canada census data for
information on socio-demographic characteristics of
subjectshome communities, including population size
and average income levels. Data manipulation and prep-
aration were performed using SAS software, while statis-
tical and regression analyses were performed using
Cohort identification
We identify all hospital admissions (n= 20,914 admis-
sions) for Caesarean section surgeries (Canadian Classifi-
cation of Health Interventions code 5.MD.60.XX) in the
province of New Brunswick, Canada, during the period
from April 2004 to March 2014.
Outcome variable
Among these patients, we identified those having any of
the following four groups of complications related to
their surgical delivery
Postpartum hemorrhage International
Classification of Diseases (ICD, version 10) code
Defined as: Excess blood loss from uterine
bleeding associated with obstetric labor or
childbirth. It is defined as blood loss greater than
500 ml or of the amount that adversely affects the
maternal physiology, such as blood pressure and
hematocrit . Hemorrhage defined as blood loss
in excess of 500 ml after vaginal delivery or more
than 1000 ml after a Caesarean section.(icd1
Postpartum sepsis ICD code O85;
Includes postpartum sepsis, puerperal peritonitis,
puerperal pyemia
Postpartum infection ICD code O86; and,
Includes: surgical wound complications and
infections, other infections of genital tract, urinary
tract infection, pyrexia of unknown origin, and
other specified puerperal infections.
Disseminated intravascular coagulation (DIC)ICD-
10 code D65.
We coded the maternal complications outcome vari-
able as 1 if any of the above complications followed sur-
gery during the hospital stay, and 0 otherwise.
Complications were based on ICD 10 classifications. Complete listings
of ICD 10 codes are available from the World Health Organization at:
DIC is an extremely rare complication in our dataset with fewer than
5 occurrences. Results are robust to its inclusion or exclusion.
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Independent variable definitions
For each C-Section surgery, we identified the responsible
physician (using the masked physician number) listed in
the discharge abstract record as being the physician most
responsible for the surgical procedure.
We summed the
number of C-Sections performed and defined physician
caseload volume as the average annual number of surger-
ies performed by the physician over the previous 2 years
(i.e., 730 days).
After matching to physician registry re-
cords, we subtracted the year of the physiciansgraduation
from medical school from the year of the surgery to iden-
tify the number of years that the physician has been prac-
tising. We also identified physician specialization from the
Physician Registry and identified those having specializa-
tions related to childbirth (i.e. maternal-fetal medicine or
obstetrics and gynecology) versus all other specializations
(who tend to be general surgeons).
We summed the number of C-Sections performed in
each hospital and calculated a continuous variable indicat-
ing the average annual number of surgeries for each hos-
pital. We created a categorical variable, separating the
four higher-volume hospitals in New Brunswicks larger
cities (Fredericton, Moncton (2), and Saint John) from the
nine lower volume hospitals in the rest of the province.
We also included patient characteristics and indications
that might be associated with risk of complications. These
include maternal age, whether the admission was deemed
elective or urgent, and comorbidity indices (ranked from 0
to 4).
Given the increasing mean maternal age and rising
prevalence of chronic conditions and obesity in the gen-
eral population, a product of which is an increasing prob-
ability that women with diabetes are becoming pregnant,
or that gestational diabetes will develop, we further con-
sidered a previous diagnosis of diabetes as a pre-existing
intraoperative or postoperative obstetric risk [22]. We cre-
ated a variable indicating whether the patient has at any
point prior to the admission (over our 10 years of data)
had a diagnosis of diabetes (ICD-10 codes E10-E14, O24,
P70.0, P70.1, R73.0).
Finally, we used the patients residential postal code
matched to census data to assign the income quintile and
population size of the community in which she resided at
time of admission. Many studies have examined sociode-
mographic factors associated with C-section delivery, in-
cluding income and living in an urban area [23]. Given the
absence of personal income information in the provincial
health administrative databases, we consider a proxy so-
cioeconomic variable of neighbourhood income quintiles:
a household size-adjusted measure of household income
at the dissemination area level (the smallest standard geo-
graphic area) drawing on 2006 census data. The popula-
tion size variable is based on 2011 census data. In New
Brunswick, three categories are included: urban centres
with populations between 100,000 and 499,000; small
towns with populations between 10,000 and 99,999; and
rural areas with populations lower than 10,000 people.
Statistical analysis
We used logistic regression to identify the odds of mater-
nal health complication occurring after C-Section surgery.
First, we adjusted our statistical model for physician char-
acteristics (i.e. case volume, experience, and
specialization), patient characteristics and indications (i.e.
age, previous diagnosis of diabetes, comorbidity level, and
elective versus urgent admission category), and calendar
year. Next, we adjusted additionally for the contextual
characteristics (i.e. community size and income quintile).
Third, we also adjusted for hospital volume. In order to
test the robustness of our results on provider volume, we
also ran models in which we included provider volume as
a categorical variable.
We analyzed data for 20,914 admissions for C-Sections in
New Brunswick, Canada, between the period of April
2004 and March 2014. Approximately 71% of admissions
occurred in the four higher-volume hospitals, while the
rest occurred in the remaining lower-volume hospitals
(Table 1). Mean maternal age was 29years and was
roughly the same across higher- and lower-volume hospi-
tals. The large majority of C-Sections admissions were
deemed to be elective,
while 10.6% were urgent. C-
Sections performed in high-volume hospitals were more
likely to be deemed urgent. Patients presenting at the
higher-volume hospitals were more likely to have only
mild or moderate comorbidities and were slightly less
likely to have a diagnosis for diabetes than those present-
ing at lower-volume hospitals.
Patients presenting in the high-volume hospitals were
considerably more likely to reside in cities than those
There may be multiple procedures recorded in the discharge abstracts
for which there may be multiple doctors (i.e. there may be both a
delivering and discharging physician). We attribute experience in the
C-Section only the physician associated with the C-Section procedure
code (i.e. the delivering physician).
The intent of this variable was to capture current caseload volume as
compared to total experience (which is measured separately as years
since graduation). A period of 2 years was selected to ensure that
temporary declines in activity (e.g. vacations or maternity leaves) did
not unduly lower our measure of current caseload.
The comorbidity level reflects the cumulative resource impact of
comorbidities on the patients stay, as assigned by the Canadian
Institute for Health Informations (CIHI) Case Mix Grouping
methodology. These are comparable to Diagnosis Related Groups in
the US. More information at
Note that the admission status (elective vs. urgent) is determined at
the time of arrival at the hospital. It is distinct from whether the C-
section itself was elective or medically indicated, and we do not have
data on the latter (and the number of elective C-sections is believed to
be very small).
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presenting at low-volume hospitals. These patients were
also more likely to come from neighbourhoods with
higher income levels.
Over 62% of surgeries in the lower-volume hospitals
were conducted by physicians who had more than 20
years since graduation, compared to only about 40%
Table 1 Characteristics of patients admitted for Caesarian section surgery in New Brunswick (April 2004 March 2014)
Characteristic Lower-volume
hospitals (n=9)
hospitals (n=4)
Number of admissions 6096 14,818 20,914
Mean maternal age 29 30 29
Admission status (% of admissions)
Elective 91.9 88.4 89.4
Urgent 8.1 11.6 10.6
Comorbidity (% of admissions)
None (0) 53.3 52.5 52.7
Mild (1, 2) 7.9 9.7 9.2
Moderate to severe (3, 4) 1.2 2.3 2.0
Missing / not applicable 37.6 35.6 36.1
Diabetes in pregnancy (% of admissions)
Diabetes mellitus or gestational diabetes 8.8 7.5 7.9
Community size classification (% of admissions)
City (population 100,000 499,999) 0.2 50.2 35.6
Small town (population 10,000-99,999) 41.2 20.9 26.8
Rural area (population < 10,000) 58.6 28.9 37.5
Neighbourhood income quintile (% of
Lowest 25.1 19.4 21.1
medium-low 21.7 18.8 19.6
Middle 19.9 19.3 19.5
Medium-high 17.4 19.9 19.1
Highest 15.7 22.6 20.6
Unknown 0.2 0.1 0.1
Physician years since graduation (% of
09 7.0 21.4 17.2
1019 30.9 38.2 36.1
20+ 62.1 40.4 46.7
Physician specialization (% of admissions)
Maternal-fetal or obstetrics & gynecology 82.2 99.8 94.6
All other specializations 17.8 0.2 5.4
Physician C-section annual volume (% of
124 34.9 18.1 23.0
2549 43.4 28.7 33.0
5074 18.4 35.6 30.6
75120 3.2 17.5 13.4
Maternal postoperative outcomes (% of admissions)
Presence of complications 2.4 2.7 2.6
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among those in the higher-volume hospitals. This find-
ing generally corresponds to physicians in rural areas be-
ing older than their more urban peers. Nearly all C-
Sections in higher-volume hospitals are performed by
surgeons specialized in either maternal-fetal medicine or
obstetrics and gynecology. In comparison, in lower-
volume hospitals, nearly 18% of C-Sections are per-
formed by surgeons with specializations other than
maternal-fetal medicine or obstetrics and gynecology
(these tend to be general surgeons). Not surprisingly,
surgical volumes of providers were higher in high-
volume hospitals than in low-volume hospitals. We
observed complications in 2.6% of all surgeries, with a
slightly higher (unadjusted) percentage in high-volume
Our database contains details on 148 providing physi-
cians, of whom 94 have provided at least one C-Section
at a higher-volume hospital and 73 of whom performed
at least one at a lower-volume hospital (Table 2).
We present the results of our regressions in Table 3.
Maternal age was inversely associated with likelihood of
complication, although falls just short of statistical sig-
nificance in two of three models. Our results suggest
that a diagnosis of diabetes during pregnancy may be
Table 2 Characteristics of hospitals with relatively low and high volumes for C-section in New Brunswick (April 2004 March 2014)
Characteristic Lower volume hospitals Higher volume hospitals Total
Hospitals (n) 9 4 13
Providers (n)
73 94 148
Annual hospital volume (mean) 95.4 332.4 263.3
Annual provider caseload (mean) 34.0 50.7 45.9
Note that a given provider can perform surgeries in multiple hospitals, thus the sum of providers working in low and high volume hospitals is greater than the
total number of providers
Table 3 Odds ratios (ORs) and 95% confidence intervals (CIs) for likelihood of maternal post-operative complication after Caesarean
section (n= 20,914 patients)
Model 1
Model 2 Model 3
OR 95% CI OR 95% CI OR 95% CI
Provider case volume 0.995 0.992 0.999 0.996 0.992 1.000 0.995 0.991 0.999
Provider years since graduation 0.965 0.956 0.974 0.962 0.953 0.972 0.965 0.956 0.975
Provider not specialized in maternal-fetal medicine
or obstetrics & gynecology
1.424 1.006 1.842 1.443 1.013 1.872 1.588 1.149 2.026
Patient age (years) 0.984 0.969 1.000 0.987 0.971 1.003 0.987 0.971 1.003
Diabetes in pregnancy 0.912 0.593 1.230 0.884 0.565 1.203 0.880 0.561 1.200
Admission category elective (vs. urgent) 0.800 0.542 1.058 0.817 0.558 1.076 0.830 0.571 1.090
Patient comorbidity (level vs. none)
1 3.420 3.157 3.683 3.415 3.152 3.679 3.397 3.133 3.661
2 1.647 1.168 2.127 1.666 1.185 2.146 1.664 1.183 2.145
3 2.517 1.960 3.074 2.621 2.063 3.179 2.616 2.058 3.174
4 4.866 4.085 5.647 5.148 4.363 5.932 5.025 4.239 5.810
Missing/not applicable 1.846 1.161 2.531 1.898 1.212 2.584 1.896 1.210 2.583
Neighbourhood income quintile (vs. lowest)
Medium-low 1.022 0.764 1.280 1.025 0.767 1.283
Middle 0.917 0.649 1.186 0.918 0.649 1.186
Medium-high 0.884 0.612 1.156 0.883 0.610 1.155
Highest 0.887 0.617 1.156 0.880 0.610 1.150
Community size ( vs. city (population
Small town (population 10,000-99,999) 1.839 1.617 2.062 1.844 1.622 2.066
rural area (population < 10,000) 1.466 1.246 1.686 1.508 1.288 1.729
Hospital mean annual C-Section volume 1.001 1.000 1.002
All regression models adjust for the listed variables and for a set of dummy variables for each year of the data period (20042014)
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protective against the likelihood of complication, but
these effects were not statistically significant in any of
the three models. Not surprisingly, patients with one or
more comorbidities were more likely to suffer from
complications than those without comorbidities. Con-
trolling for neighbourhood characteristics shows that pa-
tients living in wealthier neighbourhoods were less likely
to suffer complications as a result of their surgery. Simi-
larly, patients residing in more urban areas were also less
likely to suffer complications. In model 3, we controlled
for the mean annual hospital volume, which we found to
be weakly positively associated with the likelihood of
Provider volume was negatively associated with patient
complication, regardless of the model; in all cases, pa-
tients of doctors with higher volumes had lower odds of
complication. The odds ratio indicates that for a one
unit increase in caseload, the likelihood of complication
decreases by 0.5%, which corresponds to a decrease of
4.5% for a 10 unit increase in annual caseload. Physician
experience, as measured by years since graduation from
medical school, was also negatively correlated with com-
plications; patients of physicians who have been practis-
ing for one additional year were 3.5% less likely to suffer
from complications (16.3% less likely for a 5 year in-
crease in years of experience). The provider
specialization was also associated with the likelihood of
complication; patients of physicians whose specialization
is other than maternal-fetal medicine or obstetrics and
gynecology were more likely to suffer complications. As
mentioned previously, nearly all C-Sections occurring in
higher-volume hospitals (i.e. the urban hospitals) are
conducted by a physician specialized in maternal-fetal
medicine or obstetrics and gynecology. However,
roughly 18% of C-Sections in lower-volume (i.e. rural)
hospitals are conducted by physicians with other
In Table 4, we allow for non-linear effects of physician
volume by grouping physicians having average annual
volumes from 1 to 24, 2549, 5074 and greater than
74. Based on the point estimates of the odds ratios, it
seems that most of the decline in odds of complication
occurs once physicians provide 50 or more C-Sections
per year. However, at the 5% level, none of the categor-
ical variables are significantly different from physicians
performing from 1 to 24 surgeries per year.
We also ran separate regressions for higher- and
lower-volume hospitals individually. Results of these
models were very similar to those already presented and
to each other (not shown). Results were also robust to
alternative models (not shown) where we categorized
physiciansyears since graduation as 09 years, 1019
years and 20+ years. These models showed monotonic-
ally decreasing odds ratios with increased years of ex-
perience. Finally, in order to attempt to exclude
physicians visiting from other provinces (e.g. locums),
for whom we likely undercount volume, we ran models
excluding surgeries where the provider had fewer than 2
surgeries in the past 2 years. Findings were unchanged
(results not shown).
In this whole-population study capturing information on
roughly 21,000 C-section surgeries in New Brunswick,
Canada, we found statistically significant associations be-
tween measures of physician training and experience
and maternal post-operative complications. Specifically,
we found that each of: physician C-section caseload vol-
ume, physician years of experience, and physician
specialization in maternal-fetal medicine or obstetrics
and gynecology, was associated with decreased odds of
surgical complication. Of particular importance is the
specialization of the physician. While the large majority
of C-sections are performed by physicians specialized in
maternal-fetal medicine or obstetrics and gynecology,
our estimates suggest that surgeries performed by physi-
cians with other specializations result in 4050% more
maternal complications. These associations were of a
Table 4 Odds ratios (ORs) and 95% confidence intervals (CIs) for likelihood of maternal post-operative complication after Caesarean
section with provider case volume categories nonlinear volume effects (n= 20,914 patients)
Model 1
Model 2
Model 3
OR 95% CI OR 95% conf. Int. OR 95% CI
Provider annual volume (vs. 125)
2550 1.135 0.895 1.376 1.098 0.857 1.339 1.078 0.836 1.321
5075 0.804 0.528 1.080 0.818 0.542 1.094 0.771 0.489 1.053
75+ 0.802 0.458 1.146 0.851 0.506 1.196 0.762 0.404 1.120
Provider years since graduation 0.965 0.956 0.975 0.963 0.954 0.972 0.966 0.956 0.975
Provider not specialized in maternal-fetal
medicine or obstetrics & gynecology
1.446 1.029 1.864 1.455 1.026 1.884 1.618 1.177 2.058
Adjusted for patient age, diabetes status, elective/urgent admission status, and comorbidity and annual dummy variables
Adjusted additionally for neighbourhood characteristics (income quintile and population size)
Adjusted additionally for hospital volume
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similar magnitude regardless of whether we adjusted for
hospital volume or not.
Our associations between volume and adverse surgical
outcomes were broadly consistent with the general lit-
erature on the volume-outcome relationship [13], as
well as with the much smaller set of studies examining
volume-outcome relationships for C-section surgeries
specifically [1113].
Inconsistent with the broader literature (see for ex-
ample, [24]) is our finding of a positive association be-
tween hospital volume and complications, albeit one
that is barely statistically significant. Few studies, how-
ever, are able to control separately for both hospital and
physician volumes, and fewer also control for physician
experience and area of specialization. These are notable
strengths of this study.
One interpretation of our findings is that, at least for
C-section surgery, it is primarily the physicians experi-
ence that is important in determining patient outcomes,
such that after the physician attributes are well con-
trolled for, there is little volume-outcome relationship
remaining at the hospital level. Another possible explan-
ation is that there are not enough hospitals (n= 13) in
our dataset for accurate inferences regarding hospital
volume to be drawn.
Also consistent with the broad literature are our find-
ings with respect to patient characteristics and indica-
tions. As is commonly found, patients with comorbid
conditions, medically indicated surgical deliveries, and
patients residing in low-income and more rural areas all
face greater odds of C-section complications [25,26].
The size of the odds ratios suggest that these patient-
level effects are more important predictors of these out-
comes than are physician or hospital volume. Thus,
while our focus is on understanding the physicians role
in patient outcomes, it should not be forgotten that the
pre-existing health condition of the patient is the most
important determinant of their ultimate surgical
Key strengths of this study are that we have a large
dataset linked to physician and patient information. We
were able to adjust separately for measures of physician
experience and hospital volume. Most previous studies
of the volume-outcome relationship focus only on one
of physician or hospital volume. Thus, we make a contri-
bution by separately measuring the effect of physician
volume, physician years of experience, physician spe-
cialty, and hospital volume. To our knowledge, this is
the only Canadian study on the volume-outcome rela-
tionship for C-sections.
A limitation of this study was that we can only meas-
ure interventions performed in New Brunswick, by New
Brunswick based providers, on New Brunswick residents.
That is, we lacked information on providers who
performed procedures in other provinces, and thus are
not able to measure their volume completely if they per-
formed surgeries in other provinces (although years
since graduation and area of specialty would be mea-
sured accurately). However, our results were robust to
excluding surgeries conducted by surgeons with very
low measured volumes. Other limitations included using
area-level socioeconomic measures because individual-
level maternal socioeconomic information were not
available in the data. An additional limitation is that our
estimate of years of experience does not capture career
interruptions (e.g., parental leave), so our measure of ex-
perience should be considered an upper bound. Finally,
hospital discharge abstract lack some contextual infor-
mation which might confound the analysis. For example,
the data do not capture information on whether the C-
Section is elective, although we understand that very few
are. Further, the data do not contain information on the
duration of the labour prior to the C-section nor
whether the C-section was conducted prior to the onset
of labour.
A final limitation is that our database contains only
limited information on the complexity of the specific pa-
tients case (i.e. comorbidity index, age). It is therefore
possible that more complicated cases (on dimensions
unobserved in the database) are allocated to more expe-
rienced physicians or higher-volume hospitals, and this
could be confounding our analysis. We believe that this
is likely an unusual occurrence due to the distance be-
tween hospitals. To the extent that it occurs, however,
we are likely underestimating the impact of a surgeons
experience on reducing complications that is, had they
not had the most difficult cases, the more experienced /
high caseload physicians might have had even lower
rates of complication.
This study showed that the likelihood of maternal post-
surgical complications after Caesarean Section was nega-
tively associated with a series of measures of the sur-
geons characteristics (e.g. volume, years of experience,
and surgical specialty). This finding has particular rele-
vance in rural areas, such as New Brunswick, where
policy-makers must decide on the number of hospitals
to open in rural areas. Increasing the number of hospi-
tals therefore likely implies a trade-off between desirable
shorter travel distances for patients but undesirable
lower volumes for providers.
Future studies on this topic may wish to explore other
indicators of provider experience, including longer-term
estimates of volume, as well as the role of individual-
level socioeconomic characteristics of patients in modi-
fying the likelihood of post-C-section complications.
Leonard et al. BMC Pregnancy and Childbirth (2020) 20:37 Page 7 of 9
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CIHR: Canadian Institutes of Health Research; C-Sections: Caesarean Section
surgeries; DAD: Discharge Abstract Database; DIC: Disseminated Intravascular
Coagulation; ICD: International Classification of Diseases; MSSU: Maritime
SPOR (Strategy for Patient-Oriented Research) Support Unit; NBHRF: New
Brunswick Health Research Foundation; NB-IRDT: New Brunswick Institute for
Research, Data, and Training; NSHRF: Nova Scotia Health Research
Foundation; REB: Research Ethics Board; UNB: University of New Brunswick
NG acknowledges support from Diabetes Canada. The study was supported
non-financially by the Maritime SPOR Support Unit (MSSU), which receives fi-
nancial support from the Canadian Institutes of Health Research (CIHR), the
Nova Scotia Department of Health and Wellness, the New Brunswick Depart-
ment of Health, the Nova Scotia Health Research Foundation (NSHRF), and
the New Brunswick Health Research Foundation (NBHRF). The opinions, re-
sults, and conclusions reported in this paper are those of the authors and
are independent from the funding sources. No endorsement by the MSSU or
the named funding partners is intended or should be inferred. The authors
thank Thalia Nikolaidou (employed by the University of New Brunswick, paid
though UNB University Research Fund grants) and Chandy Somayaji
(employed by the New Brunswick Institute for Research, Data, and Training,
University of New Brunswick, paid through MSSU grants to NB-IRDT) for ex-
cellent research assistance. This work was supported by the Department of
Health of the Province of New Brunswick under a data sharing agreement
with the New Brunswick Institute for Research, Data, and Training at the Uni-
versity of New Brunswick. The results and conclusions are those of the au-
thors and no official endorsement by the Government of New Brunswick
was intended or should be inferred.
Availability of data and material
The datasets analysed during the current study are available in the New
Brunswick Institute for Research, Data and Training (
nbirdt/), a secure data repository on the University of New Brunswick
campus. Researchers wishing to access these data must make an application
to the NB-IRDT.
JB wrote the SAS code to prepare and manipulate the datasets and define
the key variables. NG provided expertise on identifying diabetes patients
within the DAD records. All authors (PL, DC, JB, NG and TM) contributed to
analysing and interpreting the patient data. PL supervised the research
assistants who prepared the Tables. PL wrote the initial draft of the
manuscript. All authors (PL, DC, JB, NG and TM) revised, edited and approved
the final manuscript.
Funding was received from the University of New Brunswicks Research
Fund. The funder played no role in the study design, data collection, analysis
or writing of the report.
Ethics approval
This study was approved by the University of New Brunswick (UNB) Research
Ethics Board (REB file 2015106) and underwent the NB-IRDTs application
and approval process. The need for consent was waived by the REB due to
the impossibility of contacting the patients (the NB-IRDT does not maintain
data on the names or contact information of patients), as per Chapter 3, Art-
icle 3.12 of the Canadian Tri-Council Policy of Ethical Conduct for Research
Involving Humans. No administrative permissions or licenses were acquired
to perform the research.
Consent for publication
Competing interests
The authors declare that they have no competing interests.
Author details
Department of Economics, University of New Brunswick, Singer Hall, Room
459, P.O. Box 4400, Fredericton, New Brunswick E3B 5A3, Canada.
Brunswick Institute for Research, Data, and Training, University of New
Brunswick, Fredericton, New Brunswick, Canada.
Department of Sociology,
University of New Brunswick, Fredericton, New Brunswick, Canada.
Received: 16 May 2018 Accepted: 30 December 2019
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... This finding is somewhat surprising given that surgeons are thought to continuously improve their skills through repeated and deliberate practice. [34][35][36][37] Our study focused exclusively on emergency CS. Hence, the variability in the context and composition of teams may outweigh factors related to variations in individual skill levels. ...
Full-text available
Objectives Emergency caesarean sections (ECS) are time-sensitive procedures. Multiple factors may affect team efficiency but their relative importance remains unknown. This study aimed to identify the most important predictors contributing to quality of care during ECS in terms of the arrival-to-delivery interval. Design A retrospective cohort study. ECS were classified by urgency using emergency categories one/two and three (delivery within 30 and 60 min). In total, 92 predictor variables were included in the analysis and grouped as follows: ‘Maternal objective’, ‘Maternal psychological’, ‘Fetal factors’, ‘ECS Indication’, ‘Emergency category’, ‘Type of anaesthesia’, ‘Team member qualifications and experience’ and ‘Procedural’. Data was analysed with a linear regression model using elastic net regularisation and jackknife technique to improve generalisability. The relative influence of the predictors, percentage significant predictor weight (PSPW) was calculated for each predictor to visualise the main determinants of arrival-to-delivery interval. Setting and participants Patient records for mothers undergoing ECS between 2010 and 2017, Nordsjællands Hospital, Capital Region of Denmark. Primary outcome measures Arrival-to-delivery interval during ECS. Results Data was obtained from 2409 patient records for women undergoing ECS. The group of predictors representing ‘Team member qualifications and experience’ was the most important predictor of arrival-to-delivery interval in all ECS emergency categories (PSPW 25.9% for ECS category one/two; PSPW 35.5% for ECS category three). In ECS category one/two the ‘Indication for ECS’ was the second most important predictor group (PSPW 24.9%). In ECS category three, the second most important predictor group was ‘Maternal objective predictors’ (PSPW 24.2%). Conclusion This study provides empirical evidence for the importance of team member qualifications and experience relative to other predictors of arrival-to-delivery during ECS. Machine learning provides a promising method for expanding our current knowledge about the relative importance of different factors in predicting outcomes of complex obstetric events.
... Regarding the size of medical units carrying out CSs, the findings from a Canadian study indicated that rural hospitals had lower odds of surgical errors and complications, whereas hospitals with high bed numbers had greater odds of errors and complications than medium bed number hospitals [58]. More recent studies have shown that the training status and experience of physicians performing CSs and the caseload volume of the medical institute play important roles in maternal postsurgical complications after CS [59]. Both individual-and hospital-level factors were associated with surgical errors and complications following CS. ...
Full-text available
Background Delayed childbearing has been noted in a high percentage of women with a previous Caesarean section (CS). Many women with CS scar defects (CSDs) present with clinical symptoms of irregular vaginal bleeding. The present study aimed to investigate bacterial colonies at CSDs in women suffering from secondary infertility. Methods This observational study included 363 women with secondary infertility who visited the Assisted Reproduction Unit between 2008 and 2013. Among them, 172 women with a previous CS and 191 women with no previous CS were approached. The women with a previous CS had their CS operations in the past 1 to 14 years, with a mean of 3.5 years. The presence of CSDs was detected by vaginal ultrasonography. Bacteriology cultures of specimens taken from the uterine niches in those with CSDs were collected during Day 7 to Day 10 of the follicular phase. Specimens were obtained from the endocervical canal for bacterial culture in those without CSDs. The main outcome measure was the detection of the growth of bacterial colonies. Results CSDs were found in 60.4% (96 of 159) of women with a previous CS. In women with a previous CS, bacterial colonies were identified in 89.6% (86 of 96) and 69.8% (44 of 63) of women with and without CSDs, respectively. In women with no previous CS, 49.7% (88 out of 177) of bacterial cultures of endocervical samples showed bacterial colony growth. Gram-positive cocci (P = 0.0017, odds ratio (OR) = 1.576, 95% confidence intervals (CI) -22.5 to − 5.4) and Gram-negative rods (P = 0.0016, OR = 1.74, CI − 20.8 to − 5.0) were the most commonly isolated bacteria and contributed to approximately 90% of all microorganisms found in those with a previous CS. In women with a previous CS, more Gram-negative rods were isolated (P = 0.01, OR = 1.765, CI − 27.2 to − 3.8), especially Pseudomonas species (P = 0.02, OR = 1.97, CI − 16.7 to − 1.0), in those with visible CSDs than in those without CSDs. Conclusions Bacterial colonization at CSDs was found in a high percentage of women with secondary infertility.
Full-text available
Background The aim of this study was to identify factors associated with variability in Cesarean delivery (CD) rates amongst providers at a single institution. Methods A retrospective cohort analysis was carried out on all births at NYU Langone Medical Center from 2005–2013. Data was collected for subjects and linked to diagnosis codes for singleton and twin deliveries. Descriptive characteristics were generated for all deliveries, and inferential analysis was performed including multiple covariates for singleton deliveries in the 2010–2013 cohort, including both univariate and multivariate regression analyses to identify factors associated with higher CD rates. Results 37,692 deliveries were identified at our institution during the study period, performed by 88 unique providers. The mean CD rate was 29.6%, with a range for individual physicians from 9.9% to 75.6%. In multivariate regression analysis, CD rate was directly correlated with average patient age, physician male gender, proportion of high-risk deliveries, and Maternal-Fetal Medicine specialty, and it was inversely correlated with total number of deliveries by physician and forceps delivery rate. There was no significant difference in CD rates between group and solo practices. Within the same group practice, each member’s CD rate was strongly correlated with the average CD rate of the group. Conclusion Our study demonstrates the wide range of CD rates for providers practicing within the same institution and reiterates the association of CD rates with patient age, high-risk pregnancy, and provider volume. Among operative vaginal deliveries, forceps delivery rate was associated with lower CD rates whereas vacuum delivery rate was not. Despite these findings, practice patterns within individual practices appear to contribute significantly to the wide range of CD rates.
Full-text available
OBJECTIVE To assess the relationship between indicators of socioeconomic status and cesarean section in public hospitals that adopt standardized protocols of obstetrical care. METHODS This was a prospective cohort study conducted between May 2005 and January 2006 with 831 pregnant women recruited from 10 public primary care clinics in São Paulo, Brazil. Demographic and clinical characteristics were collected during pregnancy. The three main exposures were schooling, monthly family income per capita, and residential crowding. The main outcome was cesarean section at three public hospitals located in the area. Crude and adjusted risk ratios (RR), with 95% confidence intervals were calculated using Poisson regression with robust variance. We examined the effects of each exposure variable on cesarean section accounting for potential confounders by using four different models: crude, adjusted by mother’s characteristics, by obstetrical complications, and by the other two indicators of socioeconomic status. RESULTS Among the 757 deliveries performed in the public hospitals, 215 (28.4%) were by cesarean section. In the bivariate analysis, cesarean section was associated with higher family income per capita, higher education, lower residential crowding, pregnancy planning, white skin color, having a partner, and advanced maternal age. In the multivariate analysis, after adjustment for covariates, none of the socioeconomic status variables remained associated with cesarean section. CONCLUSIONS In this group, the chance of women undergoing cesarean section was not associated with indicators of socioeconomic status only, but was defined in accordance with major obstetric and clinical conditions.
Full-text available
Objective Financial incentives may encourage private for-profit providers to perform more caesarean section (CS) than non-profit hospitals. We therefore sought to determine the association of for-profit status of hospital and odds of CS. Design Systematic review and meta-analysis. Data sources MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews from the first year of records through February 2016. Eligibility criteria To be eligible, studies had to report data to allow the calculation of ORs of CS comparing private for-profit hospitals with public or private non-profit hospitals in a specific geographic area. Outcomes The prespecified primary outcome was the adjusted OR of births delivered by CS in private for-profit hospitals as compared with public or private non-profit hospitals; the prespecified secondary outcome was the crude OR of CS in private for-profit hospitals as compared with public or private non-profit hospitals. Results 15 articles describing 17 separate studies in 4.1 million women were included. In a meta-analysis of 11 studies, the adjusted odds of delivery by CS was 1.41 higher in for-profit hospitals as compared with non-profit hospitals (95% CI 1.24 to 1.60) with no relevant heterogeneity between studies (τ²≤0.037). Findings were robust across subgroups of studies in stratified analyses. The meta-analysis of crude estimates from 16 studies revealed a somewhat more pronounced association (pooled OR 1.84, 95% CI 1.49 to 2.27) with moderate-to-high heterogeneity between studies (τ²≥0.179). Conclusions CS are more likely to be performed by for-profit hospitals as compared with non-profit hospitals. This holds true regardless of women's risk and contextual factors such as country, year or study design. Since financial incentives are likely to play an important role, we recommend examination of incentive structures of for-profit hospitals to identify strategies that encourage appropriate provision of CS.
Full-text available
Background The surgeon volume-outcome relationship has been discussed for many years and its existence or nonexistence is of importance for various reasons. A lot of empirical work has been published on it. We aimed to summarize systematic reviews in order to present current evidence. Methods Medline, Embase, Cochrane database of systematic reviews (CDSR), and health technology assessment websites were searched up to October 2015 for systematic reviews on the surgeon volume-outcome relationship. Reviews were critically appraised, and results were extracted and synthesized by type of surgical procedure/condition. ResultsThirty-two reviews reporting on 15 surgical procedures/conditions were included. Methodological quality of included systematic reviews assessed with the assessment of multiple systematic reviews (AMSTAR) was generally moderate to high albeit included literature partly neglected considering methodological issues specific to volume-outcome relationship. Most reviews tend to support the presence of a surgeon volume-outcome relationship. This is most clear-cut in colorectal cancer, bariatric surgery, and breast cancer where reviews of high quality show large effects. Conclusions When taking into account its limitations, this overview can serve as an informational basis for decision makers. Our results seem to support a positive volume-outcome relationship for most procedures/conditions. However, forthcoming reviews should pay more attention to methodology specific to volume-outcome relationship. Due to the lack of information, any numerical recommendations for minimum volume thresholds are not possible. Further research is needed for this issue.
Full-text available
Background: Group specific blood is often cross-matched ready for all patients scheduled for caesarean section in anticipation of haemorrhage during the surgery. This study was conducted to determine the risk factors for blood transfusion during anaesthesia for caesarean section. Methods: This was a prospective cross-sectional study. A total of 706 pregnant patients scheduled for emergency or elective Caesarean section at the University College Hospital, Ibadan, Nigeria between March and August 2011 were recruited. Participants were followed-up from the date of delivery till the end point of the study which could fall into either of the following conditions: satisfactory post-operative clinical status up to 48 hours post-delivery or death. Transfusion rate was determined and Chi-square test was used to determine if there exist an association between blood transfusion status and preoperative haematocrit level, years of experience of obstetrician, indication for Caesarean Section(CS), CS type (primary or repeat) and HIV status. Results: Transfusion rate was 9.1 %; variables found to be significantly associated with blood transfusion were; preoperative haematocrit less than 26%, increasing parity, years of experience of resident obstetrician, indication for CS (bleeding or not bleeding) and estimated blood loss. Being HIV positive does not increase the need for blood transfusion. Conclusion: Preoperative anaemia, increasing parity and severe blood loss at surgery significantly contribute to the requirement for blood transfusion in patients undergoing caesarean section.
Objective: To examine the causal effect of a hospital's experience with treating hip fractures (volume) on patient treatment outcomes. Data sources: We use a full sample of administrative data from German hospitals for 2007. The data provide detailed information on patients and hospitals. We also reference the hospitals' addresses and the zip codes of patients' place of residence. Study design: We apply an instrumental variable approach to address endogeneity concerns due to reverse causality and unobserved patient heterogeneity. As instruments for case volume, we use the number of potential patients and number of other hospitals in the region surrounding each hospital. Principal findings: Our results indicate that after applying an instrumental variables (IV) regression of volume on outcome, volume significantly increases quality. Conclusions: We provide evidence for the practice-makes-perfect hypothesis by showing that volume is a driving factor for quality.
Introduction: Cesarean delivery (CD) rates are rising due to multiple factors, including less use of operative vaginal delivery (OVD) and vaginal birth after cesarean delivery (VBAC), which often reflect local obstetric practices. Objectives of the study were to analyze the relations between CD, these practices and perinatal outcomes. Material and methods: We included all deliveries in the 72 hospitals of Lombardia, a Region in Northern Italy, during the year 2013. The delivery certificate was used as data source. Pearson's correlation coefficient and logistic regression were used for statistical analysis. Results: We included 87 896 deliveries. The number of deliveries per hospital ranged from 140 to 6123. The rate of CD was 28.3% (range 9.9-86.4%), OVD 4.7% (range 0.2-10.0%) and VBAC 17.3% (range 0-79.2%). We found a significant inverse correlation between rates of overall CD and OVD (r = - 0.25, p = 0.04). The correlation between rate of overall CD and VBAC was also inverse and significant (r = -0.57, p-value<0.001). There was no association between overall CD rate and the rates of Apgar score at 5 min < 7 in term and late preterm neonates (r = - 0.92, p = 0.46) and of perinatal mortality (r = -0.19, p = 0.13), respectively. The associations were independent of hospital volume of activity. Conclusions: An obstetric practice that encourages vaginal instrumental delivery in delayed second stage of labor or vaginal birth after previous CD, could reduce the rising CD rate. This will require a change in obstetric culture, continuing education of healthcare providers, and leadership. This article is protected by copyright. All rights reserved.
Introduction: There is limited research data on unassisted childbirth (a planned out-of-hospital birth without the attendance of a regulated care provider) in Canada; this means that there is a lack of understanding of its prevalence and of the childbearing women's motivations. This study aimed to uncover women's reasons for planning to give birth in the absence of an attendant licensed to practice in New Brunswick, in order to create insight into mainstream maternity care practices through those who have rejected them. Methods: In-depth qualitative interviewing with women who have had planned home births in New Brunswick in the past 10 years. Results: Participants had a variety of motivations and influences that played in their decision to have an unassisted home birth, including deeply held beliefs about childbirth and the need to manifest these beliefs in their experiences of birth. Participants expressed their desire to be the locus of control in their childbirth experience and believed they could best accomplish this outside of the hospital setting. Influences included ideological stance toward birth, the attitudes of their families and friends, and birth stories they had heard. Conclusion: This study demonstrates that when women's needs are not met by mainstream health services, some will choose to give birth in the absence of a skilled provider or independent attendant. This gives rise to the need for discussion between all care providers and parturient women to better understand unmet needs and unaddressed fears around hospital birth.
Background: Marked variation across hospitals in adverse maternal outcomes in cesarean deliveries is reported, including anesthesia-related adverse events (ARAEs). Identification of hospital-level characteristics accounting for this variation may help guide interventions to improve anesthesia care quality. In this study, we examined the association between hospital-level characteristics and ARAEs in cesarean deliveries and assessed individual hospital performance. Methods: Discharge records for cesarean deliveries, ARAEs, and patient characteristics in the State Inpatient Database for New York State 2009 to 2011 were identified with International Classification of Diseases, Ninth Revision, Clinical Modification codes. The hospital reporting index was calculated as the sum of International Classification of Diseases, Ninth Revision, Clinical Modification codes divided by the number of discharges. Data on hospital characteristics were obtained from the American Hospital Association and the Area Health Resources files. Multilevel modeling was used to examine the association of hospital-level characteristics with ARAEs and to assess individual hospital performance. Results: The study included 236,960 discharges indicating cesarean deliveries in 141 hospitals; 1557 discharges recorded at least 1 ARAE (6.6 per 1000; 95% confidence interval [CI], 6.2-6.9). The following factors were associated with a significantly increased risk of ARAEs: Charlson comorbidity index ≥ 1 (adjusted odds ratio [aOR], 1.2), multiple gestation (aOR, 1.3), postpartum hemorrhage (aOR, 1.5), general anesthesia (aOR, 1.3), hospital annual cesarean delivery volume <200 (aOR, 2.3), and reporting index (aOR, 1.1 per 1 increase per discharge). Fifteen percent of the between-hospital variation in ARAEs was explained by the hospital annual cesarean delivery volume and 6% by the reporting index. Eight hospitals (6%) were classified as good-performing, 104 (74%) as average-performing, and 29 (21%) as bad-performing hospitals. Compared with good-performing hospitals, a 2.3-fold (95% CI, 1.7-3.0) and 5.9-fold (95% CI, 4.5-7.8) increase in the rate of ARAEs was observed in average- and bad-performing hospitals, respectively. Bringing up bad-performing hospitals to the level of average-performing hospitals would prevent 466 ARAEs (30%). Conclusions: Low cesarean delivery volume is the strongest hospital-level predictor of ARAEs in cesarean deliveries and the main determinant of between-hospital variation. Future study to identify other factors and interventions to improve performance in bad-performing hospitals is warranted.