Can J Gastroenterol Vol 21 No 7 July 2007 435
Do physician recommendations for colorectal cancer
screening differ by patient age?
Maida J Sewitch PhD1, Caroline Fournier MSc2, Martin Dawes MD3, Mark Yaffe MD MClSc3, Linda Snell MD4,
Mark Roper MD3, Patrizia Zanelli MDCM5, Alan Pavilanis MD3
1Department of Medicine, McGill University; 2Department of Clinical Epidemiology, The Research Institute of the McGill University Health
Centre; 3Department of Family Medicine; 4Division of General Internal Medicine and Centre for Medical Education; 5Divisions of General
Internal Medicine and Critical Care, McGill University, Montreal, Quebec
Correspondence: Dr Maida J Sewitch, McGill University Health Centre, 687 Pine Avenue West, V Building, Montreal, Quebec H3A 1A1.
Received for publication June 21, 2006. Accepted October 3, 2006
MJ Sewitch, C Fournier, M Dawes, et al. Do physician
recommendations for colorectal cancer screening differ by
patient age? Can J Gastroenterol 2007;21(7):435-438.
Colorectal cancer screening is underutilized, resulting in preventable
morbidity and mortality. In the present study, age-related and other
disparities associated with physicians’ delivery of colorectal cancer
screening recommendations were examined. The present cross-
sectional study included 43 physicians and 618 of their patients, aged
50 to 80 years, without past or present colorectal cancer. Of the
285 screen-eligible patients, 45% received a recommendation.
Multivariate analyses revealed that, compared with younger nonde-
pressed patients, older depressed patients were less likely to receive
fecal occult blood test recommendations, compared with no recom-
mendation (OR=0.31, 95% CI 0.09 to 1.02), as well as less likely to
receive colonoscopy recommendations, compared with no recom-
mendation (OR=0.14; 95% CI 0.03 to 0.66). Comorbidity and mari-
tal status were associated with delivery of fecal occult blood test and
colonoscopy recommendations, respectively, compared with no rec-
ommendation. In summary, patient age and other characteristics
appeared to influence physicians’ delivery of colorectal cancer
screening and choice of modality.
Key Words: Ageism; Colorectal cancer; Disparity; Screening
Les recommandations des médecins à l’égard
du dépistage du cancer colorectal diffèrent-
elles selon l’âge des patients ?
Le dépistage du cancer colorectal est sous-utilisé, ce qui entraîne une mor-
bidité et une mortalité qui pourraient être prévenus. Dans la présente
étude, on évalue les disparités reliées à l’âge et à d’autres facteurs associés
aux recommandations du médecin en matière de dépistage du cancer
colorectal. La présente étude transversale incluait 43 médecins et 618 de
leurs patients, de 50 à 80 ans, qui n’avaient jamais été atteint de cancer
colorectal. Des 285 patients admissibles au dépistage, 45 % ont reçu une
recommandation. D’après les analyses multivariées, comparativement aux
patients non dépressifs plus jeunes, les patients dépressifs plus âgés étaient
moins susceptibles de se faire recommander de subir un test de recherche
de sang occulte dans les selles que de ne recevoir aucune recommandation
(RC=0,31, 95 % IC=0,09 à 1,02) et également moins susceptibles de se
faire recommander de subir une coloscopie que de ne recevoir aucune
recommandation (RC=0,14, 95 % IC=0,03 à 0,66). La comorbidité et l’é-
tat matrimonial s’associaient aux recommandations de test de recherche
de sang occulte dans les selles et de coloscopie, respectivement, par rap-
port à l’absence de recommandation. Bref, l’âge du patient et d’autres
caractéristiques semblent influer sur la prestation, par le médecin, du
dépistage du cancer colorectal et sur le choix de modalités.
olorectal cancer (CRC) screening is underutilized despite
the evidence supporting reductions in CRC morbidity and
mortality in average-risk individuals who are 50 years of age
and older (1-4). Underutilization in CRC screening may stem,
in part, from the lack of consensus regarding screening guide-
lines across organizations (5-7). However, patient demographic
and clinical characteristics may also account for physicians’
decisions to recommend screening (8-11). Although most
reports focused on racial, ethnic and socioeconomic status as
sources of screening disparities (12-17), ageism has been sug-
gested as a potential barrier to delivery of screening (11).
Ageism, for the purposes of the present study, is defined as dis-
crimination against elderly people. Because physicians may
disfavour the elderly when delivering preventive health care
services, the present report addresses the influence of patient’s
age on physician’s delivery of a recommendation for CRC
screening in primary care. Given that individuals 50 years of
age and older constitute a rapidly growing population and that
increasing age is associated with increasing cancer rates, the
sources of age-related disparities in delivery of CRC screening
warrant further elucidation.
Participants and data sources
A cross-sectional study was conducted among family and internal
medicine physicians and their patients at three McGill University-
affiliated centres in Montreal, Quebec (2004 to 2005). Delivery of
CRC screening recommendations included fecal occult blood test
(FOBT), colonoscopy, double-contrast barium enema (DCBE)
and flexible sigmoidoscopy (FS). Physician’s delivery of CRC
screening recommendation was assessed by physician self-administered
questionnaire immediately following the patient’s index office visit,
defined as a scheduled appointment for any of the following:
annual examination, periodic health examination, follow-up or
specific problem. Eligible patients were aged 50 to 80 years, under
treatment at the clinic for at least two years, and without past or
©2007 Pulsus Group Inc. All rights reserved
present CRC. Patient characteristics were assessed by self-admin-
istered questionnaire at the index visit and included sociodemo-
graphic characteristics, cancer screening history and eligibility,
comorbidity (Charlson co-morbidity index) (18) and depression
(Center for Epidemiologic Studies Depression Scale) (19,20). Screen-
eligibility was defined as not having received any of the following:
FOBT in the past two years, colonoscopy in the past 10 years and
DCBE or FS in the past five years.
Patients were stratified by age (50 to 64 years and 65 to 80 years).
Characteristics were compared using χ2and t tests, as appropriate.
Because only one recommendation was given for DCBE and FS
each, these patients were excluded from further analysis.
Multinomial logistic regression analyses were performed to assess
patient characteristics as predictors of a three-category outcome:
not delivering a screening recommendation, delivering an FOBT
recommendation and delivering a colonoscopy recommendation.
The SAS CATMOD (SAS Inc, USA) procedure (21) was used to
contrast the three mutually exclusive categories for each of the
following outcome scenarios of recommendation delivered: FOBT
versus none, colonoscopy versus none and FOBT versus
colonoscopy. ORs and 95% CIs were generated for each outcome
scenario. Independent variables included patient age, depression,
comorbidity, marital status and an age group by depression status
interaction. Comorbidity was dichotomized at the cutpoint of one
comorbid condition (median=0.67). Sex was excluded from the
final model because it was not statistically significant and did not
confound the age-delivery of recommendation relationship. To
account for limited statistical power of testing the interaction, given
unequal numbers of patients in the two groups, the decision was
taken to include the interaction if it was significant at a liberal
0.10level. For all other tests, statistical significance was set at P=0.05.
In total, 43 physicians and 618 patients participated. Of the
285 (46%) screen-eligible patients, 48% were aged 65 years
and older. Compared with screen-eligible patients, nonscreen-
eligible patients were significantly older (67 versus 65 years;
P=0.003) and had more comorbidity (48% versus 38%;
P=0.02) (data not shown). Table 1 compares the characteris-
tics and screening recommendations of screen-eligible patients
by age group. Compared with younger patients, older patients
had significantly more comorbidity and less depression. A sig-
nificantly smaller proportion of older patients was recom-
mended screening compared with their younger counterparts
(37% versus 53%, P=0.0056). FOBT recommendation did not
differ by age group. Colonoscopy recommendation was given
to more younger than older patients (30% versus 19%,
Table 2 shows the associations between patient characteris-
tics and the three outcome scenarios. In univariate analyses for
FOBT recommendation (column 2), patients with comorbidity
(OR=0.52, 95% CI 0.27 to 0.99) were less likely to receive an
FOBT recommendation compared with no recommendation.
A trend was revealed that indicated older patients (OR=0.59,
95% CI 0.32 to 1.09) were less likely to receive an FOBT rec-
ommendation compared with no recommendation. In multi-
variate analysis, the age group by depression interaction was
found to be statistically significant. This interaction indicated
that older depressed patients (OR=0.31, 95% CI 0.09 to 1.02)
versus younger nondepressed patients were less likely to
receive an FOBT recommendation, compared with no recom-
mendation. In addition, a trend was revealed showing that
patients with comorbidity (OR=0.57, 95% CI 0.29 to 1.13)
were less likely to receive an FOBT recommendation com-
pared with no recommendation.
In univariate analyses for colonoscopy recommendation
(column 3), older patients (OR=0.48, 95% CI 0.27 to 0.86)
were less likely to receive a colonoscopy recommendation
while married patients (OR=2.05, 95% CI 1.13 to 3.74) were
more likely to receive a colonoscopy recommendation, com-
pared with no recommendation. In multivariate analyses,
married patients (OR=1.86, 95% CI 0.99 to 3.51) were more
likely to receive a colonoscopy recommendation compared
with no recommendation, although this association did not
reach statistical significance. In addition, the age by depres-
sion interaction was found to be statistically significant. This
interaction implied that older depressed patients (OR=0.14,
95% CI 0.03 to 0.66) were less likely to receive a colonoscopy
recommendation than younger nondepressed patients, com-
pared with no recommendation.
In both univariate and multivariate analyses that compared
FOBT and colonoscopy recommendations, no associations
were found between patient characteristics and physician
delivery of screening recommendations.
Most current guidelines advocate that persons over the age of
50 years be screened with FOBT every one to two years or
with colonoscopy every 10 years (5-7). Although disparities in
CRC screening recommendation have been documented, their
nature and role were unclear. Our study provides evidence for
Sewitch et al
Can J Gastroenterol Vol 21 No 7 July 2007436
Demographic and clinical characteristics and physicians’
recommendations for colorectal cancer screening in
screen-eligible patients according to age group
Age < 65 yearsAge ≥ ≥ 65 years
Characteristicn (%)n (%)P
Male 59 (39.6) 47 (34.6)
Female 90 (60.4)89 (65.4)
Single/divorced/widowed53 (35.6) 63 (46.3)
Married 96 (64.4)73 (53.7)
High school or less 49 (32.9) 56 (41.5)
College or university 100 (67.1)79 (58.5)
None107 (71.8)67 (49.3)
At least one 42 (28.2)69 (50.7)
Absent89 (60.5) 99 (74.4)
Present58 (39.5)34 (25.6)
Any modality 78 (52.7)50 (36.8) 0.0056
FOBT33 (22.3)25 (17.8)0.343
Colonoscopy44 (29.7) 26 (18.5)0.028
FOBT Fecal occult blood test
age-related disparities in physician delivery of CRC screening
recommendation to screen-eligible, average-risk persons. The
interaction between age group and depression was the most
important determinant of physicians’ delivery of a colonoscopy
recommendation. Although a greater proportion of patients in
the younger age group were depressed, only depression in the
older age group was associated with lack of delivery of a recom-
mendation for colonoscopy. Several reasons for this observa-
tion can be postulated. Primary care patients who present with
chronic depression may offset physicians’ screening offerings to
address the more pressing issue of depression. Because depres-
sion in younger patients did not seem to influence delivery of
CRC screening recommendation, older age may be a key factor
driving physicians’ decision to not recommend colonoscopy
screening. Physicians may be taking into account the arduous
preparation and invasiveness of the procedure, which may be
more difficult at advanced ages. Alternatively, primary care
patients who present with a new, unexplained episode of depres-
sion may prompt physicians to recommend screening because a
new depressive episode may be an underlying symptom of
occult malignancies such as CRC (22,23). The age by depres-
sion interaction also indicated that physicians recommended
FOBT 69% less often to older depressed patients versus
younger nondepressed patients. Similarly, because FOBT is
self-administered, providers may perceive that older depressed
patients will find preparation and performance of the examina-
tion to be a daunting task and will, therefore, be less compliant.
The role of comorbidity was explored as a factor that might
influence physician delivery of screening recommendations. We
expected that, because comorbidity generally increases with
increasing age, older patients would have more comorbidity and
would be less likely to receive a screening recommendation
regardless of the modality. However, there was no association
between an age by comorbidity interaction and delivery of
screening recommendation for any modality. In contrast,
patients with comorbidity, regardless of age, were marginally
less likely to receive an FOBT recommendation. The clinical
importance of this finding lies in the fact that physicians often
consider quality versus quantity of life when offering screening
for a malignancy (24) and may perceive that patients with
comorbidity would not derive sufficient benefit from screening.
Furthermore, providers may not offer FOBT to patients with
comorbid conditions because FOBT may be more difficult to
complete than examinations that are administered by health
care professionals. Collectively, these results suggest that
comorbidity operates independently of ageism as a determi-
nant of physician delivery of FOBT recommendation.
Additionally, we observed an association between marital
status and physician delivery of colonoscopy recommendation.
Although this association remained marginally significant in
the presence of other patient characteristics, the clinical impli-
cation is noteworthy. Physicians may perceive that married
compared with unmarried patients have greater social support,
are more stable, and may, therefore, be more compliant with
screening. This finding suggests that marital status may be an
important factor that influences CRC screening recommenda-
tions. Another explanation is that marital status may promote
screen-seeking behaviour; married patients may ask their
physicians to recommend screening because their spouse
Surprisingly, no significant association was found between
patient characteristics and delivery of FOBT versus colonoscopy
recommendation. Possibly, the lack of identifiable predictors
between these two modalities stems from the fact that CRC
Disparities in colorectal cancer screening delivery
Can J Gastroenterol Vol 21 No 7 July 2007437
Univariate and multivariate results of multinomial logistic regression analyses: Associations between patient
characteristics and physician recommendations for colorectal cancer screening (n=283)
FOBT versus none Colonoscopy versus none FOBT versus colonoscopy
OR (95% CI) OR (95% CI)OR (95% CI)
CharacteristicAOR (95% CI) AOR (95% CI)AOR (95% CI)
<65 years 1.0 1.01.0
≥65 years0.59 (0.32–1.09)*0.48 (0.27–0.86)*** 1.23 (0.60–2.52)
0.77 (0.37–1.63) 0.78 (0.38–1.60)0.99 (0.42–2.32)
Absent 1.01.0 1.0
Present 0.64 (0.32–1.25) 0.71 (0.39–1.32)0.89 (0.41–1.96)
0.74 (0.30–1.78)1.15 (0.52–2.55) 0.64 (0.24–1.66)
Age by depression interactions†
<65 years by absent 1.0 1.0 1.0
≥65 years by present0.31 (0.09–1.02)** 0.14 (0.03–0.66)*** 2.18 (0.36–13.26)
Single/divorced/widowed 1.0 1.01.0
Married 1.50 (0.81–2.81) 2.05 (1.13–3.74)***0.73 (0.35–1.54)
1.29 (0.68–2.46) 1.86 (0.99–3.51)**0.69 (0.32–1.49)
At least one0.52 (0.27–0.99)*** 0.64 (0.36–1.15) 0.82 (0.38–1.73)
0.57 (0.29–1.13)* 0.77 (0.41–1.44) 0.75 (0.34–1.64)
Multinomial logistic models assessing one of the following outcome scenarios: delivery of fecal occult blood test (FOBT) or no recommendation (column 2); deliv-
ery of colonoscopy or no recommendation (column 3); delivery of FOBT or colonoscopy (column 4); *P≤0.10; **P=0.05; ***P<0.01; †Univariate results not available
for the age group by depression interaction. AOR Adjusted odds ratio
screening guidelines are inconsistent across organizations, leaving
physicians to base their modality choice on personal belief and
preference. Physicians may adhere to one screening modality
and thus may choose to not give any screening recommendation
as opposed to recommending an alternative screening modality.
Therefore, factors such as patient characteristics that could
potentially influence recommendations would not be observed
between different screening modalities.
There are several potential study limitations worth discussing.
The first is the lack of documentation regarding the nature of
the index visit. Primary care physicians are more likely to dis-
cuss CRC screening during visits for routine physicals than for
follow-ups (25), which may be more common among older
individuals with comorbidity. To address this possibility, we
assessed the age-comorbidity relationship between screen-
eligible and nonscreen-eligible patients. We found that older
patients had significantly more comorbidity than younger ones
in the screen-eligible patients only. Therefore, it is plausible
that more of the older, unwell patients were visiting the clinics
for follow-ups. However, the lack of association between the
age-comorbidity interaction and delivery of a screening recom-
mendation indicates that older patients with comorbidity were
as likely to receive a screening recommendation as any other
patient. This suggests that, in our study population, the nature
of the medical visit did not influence delivery of the screening
recommendation. Nevertheless, physicians may have recom-
mended screening regardless of the nature of the medical visit
owing to a Hawthorn effect. Another limitation is that
because ascertainment of patient screen-eligibility was by self-
report, patients may have misunderstood the test description
and failed to report a personal history of screening. Finally, dif-
ferences between patient’s and physician’s modality of choice
were not documented; physicians may have under-reported
screening delivery if the patient immediately refused to comply
with the screening modality recommended.
Our findings emphasize the complexity of CRC screening dis-
parities that appear to vary with different screening modalities.
Our results suggest that patient characteristics such as age and
marital status influence delivery of colonoscopy while comor-
bidity influences delivery of FOBT screening. Age disparities
were found for individuals aged 65 years and older who were
depressed, which may, in turn, delay delivery of preventive care
to older people who would be good candidates for CRC screen-
ing and could benefit from early detection and treatment.
Further insight into the causes of age-related and other dispari-
ties may help overcome barriers to delivery of CRC screening.
ACKNOWLEDGEMENTS: This research was supported by a
grant from the Fonds de la Recherche en Santé du Québec
(FRSQ). Maida J Sewitch, PhD is supported as a Research
Scientist of the Canadian Cancer Society through an award from
the National Cancer Institute of Canada.
Sewitch et al
Can J Gastroenterol Vol 21 No 7 July 2007438
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