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EFFICACY OF CHIROPRACTIC MANUAL THERAPY ON INFANT
COLIC:APRAGMATIC SINGLE-BLIND,RANDOMIZED
CONTROLLED TRIAL
Joyce E. Miller, BS, DC,
a
David Newell, PhD,
b
and Jennifer E. Bolton, PhD
c
ABSTRACT
Objective: The purpose of this study was to determine the efficacy of chiropractic manual therapy for infants with
unexplained crying behavior and if there was any effect of parental reporting bias.
Methods: Infants with unexplained persistent crying (infant colic) were recruited between October 2007 and
November 2009 at a chiropractic teaching clinic in the United Kingdom. Infants younger than 8 weeks were
randomized to 1 of 3 groups: (i) infant treated, parent aware; (ii) infant treated, parent unaware; and (iii) infant not
treated, parent unaware. The primary outcome was a daily crying diary completed by parents over a period of 10 days.
Treatments were pragmatic, individualized to examination findings, and consisted of chiropractic manual therapy of
the spine. Analysis of covariance was used to investigate differences between groups.
Results: One hundred four patients were randomized. In parents blinded to treatment allocation, using 2 or less hours
of crying per day to determine a clinically significant improvement in crying time, the increased odds of improvement
in treated infants compared with those not receiving treatment were statistically significant at day 8 (adjusted odds
ratio [OR], 8.1; 95% confidence interval [CI], 1.4-45.0) and at day 10 (adjusted OR, 11.8; 95% CI, 2.1-68.3). The
number needed to treat was 3. In contrast, the odds of improvement in treated infants were not significantly different in
blinded compared with nonblinded parents (adjusted ORs, 0.7 [95% CI, 0.2-2.0] and 0.5 [95% CI, 0.1-1.6] at days 8
and 10, respectively).
Conclusions: In this study, chiropractic manual therapy improved crying behavior in infants with colic. The findings
showed that knowledge of treatment by the parent did not appear to contribute to the observed treatment effects in this
study. Thus, it is unlikely that observed treatment effect is due to bias on the part of the reporting parent. (J Manipulative
Physiol Ther 2012;35:600-607)
Key Indexing Terms: Infant; Colic; Chiropractic; Musculoskeletal Manipulations
Excessive infant crying in otherwise healthy infants,
traditionally called infant colic, continues to be an
enigmatic condition with no known cause and no
known cure.
1-3
Afflicting between 10% to 30% of all
infants and consuming significant health care resources,
2
infant colic is a problem for parents and clinicians, both of
whom try a wide range of therapies with often disappoint-
ing results.
Despite decades of research, a clear pathogenesis has not
been elucidated. Notwithstanding, what is clear is that
underlying disease is rare in the excessively crying baby
4
and that half of those affected recover by 6 months of age,
5
with a small proportion at risk of injury
6
or long-term
developmental problems.
7-9
In an effort to help their child
with what appears to be a painful condition, some parents
choose complementary and alternative medicine (CAM),
including chiropractic manual therapy.
9-12
To date, several
randomized trials have been reported,
13-19
and although
these trials demonstrate some reduction in crying, weak-
nesses in study methodologies have compromised their
contribution to the evidence base.
20-23
A Danish study in 1999
13
showed manual therapy
resulted in a significant reduction in crying in a 2-week trial
when compared with simethicone (known to have no effect
over placebo
3
) as a control. However, the parents were not
blind to treatment allocation, which could have biased their
reports of outcome. Similarly, a British study in 2006,
comparing manual therapy with no treatment, showed
significant declines in crying in the treatment group, but
again, parents were not blind to the intervention received.
14
a
Associate Professor, Anglo-European College of Chiroprac-
tic, Bournemouth, UK.
b
Senior Lecturer, Biomedicine and Research, Anglo-European
College of Chiropractic, Bournemouth, UK.
c
Director of Research and Graduate Studies, Anglo-European
College of Chiropractic, Bournemouth, UK.
Submit requests for reprints to: Joyce E. Miller, BS, DC,
Associate Professor, 13-15 Parkwood Rd, Bournemouth, Dorset
BH5 2DF, UK (e-mail: jmiller@aecc.ac.uk).
Paper submitted January 20, 2012; in revised form June 30,
2012; accepted July 4, 2012.
0161-4754/$36.00
Copyright © 2012 by National University of Health Sciences.
http://dx.doi.org/10.1016/j.jmpt.2012.09.010
600
In contrast, a Norwegian study in 2002, which did blind the
parents to treatment allocation, showed similar reductions
in crying with manual therapy and with placebo.
15
However, the manual therapy in that trial was an
intervention nonspecific to the patient. A British study in
2005 compared 2 manual therapies, and although partici-
pants in both treatment arms showed reductions in crying,
there was no placebo group for comparison.
16
Finally, 3
South African studies showed that significant improve-
ments in crying with manual therapy over detuned
ultrasound
17
and medication
18,19
can only be found in
conference proceedings and therefore remain unpublished
in the peer-reviewed literature. Based on these studies, there
is some but not conclusive evidence to make a recommen-
dation of manual therapy for the excessively crying baby.
22
For there to be a better understanding about the efficacy of
chiropractic treatment for infants with colic, these method-
ological weaknesses should be addressed.
Therefore, the objectives of this study were to conduct a
single-blind, randomized controlled trial comparing chiro-
practic manual therapy with no treatment and to determine
whether parents' knowledge of treatment biases their report
of change in infant crying. The questions posed were as
follows: (i) in colicky infants, is there a difference in crying
time between infants who receive chiropractic manual
therapy and those who do not, and (ii) in colicky infants, is
there a difference in infant crying time between parents
blinded and parents not blinded to treatment?
METHODS
Participants
Infants with unexplained persistent crying (infant colic)
presenting to a chiropractic teaching clinic at the Anglo-
European College of Chiropractic were recruited between
October 2007 and November 2009. The “mother's
diagnosis”of colic
24-26
was used to determine eligibility
for the trial, verified by a baseline crying diary of 3 days or
more. Other inclusion criteria were as follows: patients had
to be younger than 8 weeks, born at a gestational age of 37
weeks or later, and had a birth weight of 2500 grams or
more and show no signs of other conditions or illness. The
parents of consecutively presenting infants fulfilling the
inclusion criteria were informed of the study and gave
written consent to participate. Parents completed a
questionnaire (baseline) and were then randomized to 1 of
3 groups using permutated blocks of 18 and computer-
generated allocations. These allocations were sealed in
opaque and consecutively numbered envelopes and
revealed to treating practitioners immediately before
treatment proceeded. In 2 of the 3 groups, infants received
treatment, and in the third, no treatment was administered.
In 1 of the 2 treatment groups, the parent was able to
observe the treatment and knew that the infant was being
treated. In the other 2 groups, the parent was seated behind a
screen and was not able to observe the infant. Thus, in these
2 groups, the parent was “blind”as to whether or not the
infant was treated. This resulted in 3 groups: (i) infant
treated/parent aware (treated, not blinded, or T[NB]), (ii)
infant treated/parent unaware (treated, blinded, or T[B]),
and (iii) infant not treated/parent unaware (not treated,
blinded, or NT[B]).
Participating parents were not charged for treatment;
those parents of infants in the no-treatment group were
offered a series of free treatments at the end of the study
period. There were no restrictions regarding medication or
other health care use during the trial.
Parents were informed of the interventions in all 3 groups
and gave informed consent to participate. The study received
ethics approval from the Anglo-European College of
Chiropractic Research Ethics Sub-Committee in September
2007. A research assistant was partially funded by the British
Columbia Chiropractic Association. Tomy Toy Company
donated a cuddly toy to each infant at exit of the trial.
Interventions
All treatments were administered by a chiropractic intern
with an experienced chiropractic clinician in attendance.
Treatments were pragmatic, individualized to examination
findings of the individual infant, and consisted of
chiropractic manual therapy of the spine. Specifically, this
involved low force tactile pressure to spinal joints and
paraspinal muscles where dysfunction was noted on
palpation. The manual therapy, estimated at 2 N of force,
was given at the area of involvement without rotation of the
spine. The treatment period was up to 10 days, and the
number of treatments during this period was informed by
the examination findings and parent reports. Treatment was
terminated if parents reported complete resolution of
symptoms. Infants in the blinded groups were placed by
the parent on the examination table. Thereafter, parents sat
in the examination room but behind a screen so they were
unable to observe the interaction between the practitioner
and their child. Patients in the no-treatment group were not
touched by the intern and/or clinician. The same scripted
words were spoken by the practitioner for infants in all 3
groups and consisted of “We will begin treatment now; it
will be just one more minute; that is the end of treatment;
we will stop now.”Thus, although parents were informed of
the treatment protocols in each of the 3 groups before
randomization, the implication to all parents was that their
child was being treated.
Outcome Measures
Parents were asked to complete a questionnaire
concerning infant demographics at baseline. Starting at
baseline, a 24-hour crying diary was completed throughout
the study period ending either after 10 days or at discharge
601
Miller et alJournal of Manipulative and Physiological Therapeutics
Chiropractic for the Excessively Crying InfantVolume 35, Number 8
(whichever was sooner). Crying time extracted from the
diary
26-28
was selected as the primary outcome measure a
priori. Data extraction was conducted by an assessor blind
to treatment group allocation. A global improvement scale
(GIS) was completed at either 10 days or discharge. This
scale rated the parent's impression of change in their child's
condition since beginning the treatment (1, worse; 2, no
change; 3, little improvement; 4, moderate improvement; 5,
much improvement). Parents also reported on any adverse
effects during the treatment period. To test blinding to
treatment, at the end of the trial, parents blinded to treatment
allocation were asked to guess whether or not their child
had been treated. The options were “treated,”“not treated,”
and “don't know.”
Sample Size
The trial was designed to have 80% power to detect a
significant difference at the 5% level between the groups of
at least 2-hour crying time at 10 days.
13
The SD at baseline
was estimated to be 2.5.
13
Adding 20% for dropouts, we
estimated that we needed at least 30 patients in each group.
Data Analysis
Analysis was performed per protocol. An intention-to-
treat analysis was conducted. For continuous data (reported
crying time), we compared the mean change in crying time
from baseline to each time point between groups using
analysis of covariance with age, sex, and the baseline 24-
hour crying time as covariates.
Categorical data for improvement were calculated from
both the GIS (score ≥4; moderate and much improvement)
and from cutoff scores on the 24-hour crying diary. We
chose a priori either (i) 2 hours or less in a 24-hour period or
(ii) more than 30% reduction in crying time from baseline.
From these, crude odds ratios and numbers needed to treat
(NNT) and adjusted odds ratios using logistic regression
were calculated.
Parents asked to participate
(n=116)
Declined to participate
(n=12)
Randomised (n=104)
Infants randomised to
treatment without blinding
[T (NB)]
(n=33)
Infants randomised to
treatment with blinding
[T (B)]
(n=35)
Infants randomised to no
treatment with blinding
[NT (B)]
(n=34)
Did not return
(n=2)
With 10 day data (n=26)
Discharged (n=7)
With 10 day data (n=30)
Discharged (n=5)
With 10 day data (n=22)
Dropped out (n=12)
RECRUITMENTRANDOMISATIONFOLLOW-UP
Fig 1. Flow of participants through the trial.
602 Journal of Manipulative and Physiological TherapeuticsMiller et al
October 2012Chiropractic for the Excessively Crying Infant
RESULTS
Of 116 parents of eligible infants given information
about the study, 104 were recruited and their children
randomized to 1 of the 3 groups; the remaining 12 parents
were unwilling to participate. Overrecruitment was consid-
ered appropriate because high dropouts have been noted in
other trials. Two infants were not included in the final
analysis: one due to sudden-onset illness and the other who
did not return for treatment after recruitment. Data from the
remaining 102 infants were analyzed, with 33 in the T(NB)
group, 35 in the T(B) group, and 34 in the NT(B) group
(Fig 1). There were no significant differences in baseline
characteristics between the 3 groups, except for sex, with a
greater proportion of boys in the NT(B) group and girls in
the T(B) group (Table 1). Sex has been shown to have no
effect on infant colic in other studies.
By the end of the study period (10 days), 12 patients had
dropped out in the no-treatment (NT[B]) group and 5 and 7
patients had been discharged in the blinded (T[B]) and not
blinded treatment (T[NB]) groups, respectively. The
numbers of dropouts and discharges are shown in Figure 1.
At the end of the trial period or discharge (whichever was
sooner), no adverse events were reported in any of the
infants recruited to the study. One child in the nontreatment
group reported an adverse effect of increased crying.
Of the 35 patients in the treatment group blinded to
treatment allocation, 8 (22.9%) believed that their child was
treated and 17 (48.6%) either did not know or believed that
their child was not treated (there were 10 responses either
missing or where the parent had given answers to 2 of the 3
options). Of the 34 patients in the no-treatment group
blinded to treatment allocation, 5 (14.7%) believed that
their child was not treated and 20 (58.8%) either did not
know or believed that their child was treated (there were 9
responses either missing or where the parent had given
answers to 2 of the 3 options).
Figure 2 and Table 2 show the change in crying time
from baseline values over the 10 days of the trial. The mean
crying times within each of the 3 groups significantly
decreased over time. Compared with baseline, by day 10,
the mean decrease was 44.4% (Pb.001), 51.2% (Pb.001),
and 18.6% (Pb.05) in the treatment groups (T[B] and T
[NB]) and the no-treatment (NT[B]) groups, respectively.
Comparison of treatment (T[B]) with no treatment (NT[B])
showed statistically significant differences in mean change
in crying time from baseline at days 8 and 9 in favor of
treatment. By day 10, the mean difference in the change in
crying time from baseline between patients treated and not
treated was 1.5 hours (Table 2). In contrast, there were no
statistically significant differences in the mean change in
crying time from baseline at any of the time points between
the patients of parents who were and were not blinded to
treatment (Table 2). Table 2 also shows these differences in
change scores where they were adjusted for age, sex, and
baseline crying time. Entering these potential confounders
into the analysis resulted in similar findings with a
significant difference in change scores between the blinded
treatment and the no-treatment groups from days 7 to 10,
and again, no statistically significant differences in change
scores at any time between the blinded and the nonblinded
treatment groups were observed.
To facilitate clinical interpretation of our findings, we
categorized the change in crying time in terms of
improvement. In this analysis, the odds of improvement
(crude and adjusted for baseline crying time, age, sex)
Table 1. Baseline infant characteristics
T(NB) (n = 33) T(B) (n = 35) NT(B) (n = 34)
Sex (female) 49% 66% 32% *
Age (wk) 5.21 (2.41) 4.9 (2.04) 5.25 (1.73)
Gestational
age (mo)
39.5 (1.66) 39.3 (1.38) 39.0 (1.10)
Birth weight (g) 3469 (363) 3308 (447) 3438 (502)
Crying time (h/d) 5.2 (2.2) 5.4 (2.5) 5.5 (2.1)
n = number of infants.
⁎Pb.05.
Fig 2. Mean change in crying time in the 3 groups during the trial.
603Miller et alJournal of Manipulative and Physiological Therapeutics
Chiropractic for the Excessively Crying InfantVolume 35, Number 8
were calculated. Table 3 shows data obtained for
improvement using both the GIS scale and the 2 cutoff
values for the crying time data. In the adjusted analysis
categorizing improvement using crying time scores, there
were significantly greater odds of improvement with
treatment (T[B]) compared with no treatment (NT[B]) at
days 8 and using the criterion of 2 or less hours of crying
per day, at day 10. This increase in odds of improvement
at day 8 was 8 (95% confidence interval [CI], 1.4-45) and
5 (1.5-16), and at day 10, it was 12.0 (2.1-68) and 3 (0.8-
9) using the cutoffs of 2 or less hours of crying per day
and more than 30% change, respectively. Using the GIS to
categorize improvement at the end of the trial, there was a
similar greater odds of improvement with treatment (T[B])
compared with no treatment (NT[B]). Although these
results were statistically significant, the wide CIs reflect-
ing the variability in the data and small sample sizes
indicate the need for caution and the difficulty in precisely
estimating any treatment effect in the target population.
Notwithstanding, the NNT approximated 3 (Table 3),
indicating that 3 infants need to be treated to gain one
additional improvement in crying time over no treatment.
DISCUSSION
This study investigated the effect of chiropractic manual
therapy in infants with infantile colic and the effect that
blinding has on the report of crying time by the parent. In
previous studies,
13,14,16-19
any apparent effect that an
intervention had on crying time in colicky infants has
been challenged for lack of blinding of the parents and the
consequential potential for reporting bias. In studies of
interventions for excessive crying in infants, there is no
alternative to the outcome being based on the parent's self-
report of crying behavior, and although crying diaries in
themselves have been shown to be valid measures,
27,28
the
influence of the parent knowing whether or not his/her child
was treated raises suspicions, rightly or wrongly, about any
observed treatment effect. We attempted to overcome this
impediment by purposively designing the trial to observe
what, if any, effect the parent knowing about their child's
treatment had on the report of crying time. The treatment
was based on evidence that showed that such therapy has
been implicated in reduced crying, and previous authors
have hypothesized that colic is a musculoskeletal
disorder.
13,29,30
Moderate finger pressure on irritable
muscles has shown a relaxation response in adults, which
included decreased heart rate and increased alpha and beta
brainwave activity, which hallmark a relaxation response.
30
A reduction in heart rate secondary to a therapeutic manual
impulse at the suboccipital region has been similarly
demonstrated in infants.
31
Other research corroborates the
safety of the treatment found in this trial.
32
In answer to our first question, the results of our study
showed statistically significant differences in the change in
crying time between infants receiving treatment and no
treatment in parents blinded to treatment allocation and a
greater odds of improvement in the treated group toward the
end of the 10-day trial period. Although the results were not
always statistically significant, the trend was for the treated
infants to show a greater reduction in crying than those in the
nontreated group within 2 to 3 days. This suggests that any
beneficial effect of treatment is apparent early on thus
quickly reassuring anxious and distressed parents. The
question on group allocation posed at the end of the study
suggests that the procedures taken to blind parents were
reasonably successful, and the degree of blinding was not
dissimilar between the treated and nontreated groups. When
comparing the effects of parents blinded and not blinded to
treatment, there were no significant differences in the
reduction in crying, indicating that blinding the parent had
no biasing effect on the report of infant crying behavior.
Other studies
13,14,16-19
where the lack of parental blinding
has been cited as a possible explanation for an observed
Table 2. Mean change in crying times (in hours per day; unadjusted data)
Day
Change scores (baseline −follow-up)
Unadjusted differences in change
scores (95% CI)
Adjusted differences in change
scores (95% CI)
T(B) NT(B) T(NB)
T(B) vs NT(B) T(B) vs T(NB) T(B) vs NT(B) T(B) vs T(NB)n Mean (SD) n Mean (SD) n Mean (SD)
235−0.8 (1.5) 33 −0.3 (1.6) 32 –0.5 (2.0) −0.4 (−1.4 to 0.6) −0.3 (−1.3 to 0.7) −0.2 (−1.5 to 1.1) 0.3 (−1.0 to 0.5)
335−0.7 (2.4) 33 −0.4 (1.9) 32 –0.7 (2.3) −0.4 (−1.7 to 1.0) 0.04 (−1.4 to 1.3) 0.1 (−1.7 to 1.9) 0.1 (−1.0 to 1.2)
435−0.9 (1.9) 31 0.2 (1.8) 31 –0.7 (1.6) −1.1 (−2.2 to 0.02) −0.2 (−1.3 to 0.9) −0.6 (−1.9 to 0.8) −0.2 (−1.0 to 0.7)
534−1.5 (2.3) 29 −0.3 (2.0) 30 –1.4 (2.0) −1.2 (−2.5 to 0.2) −0.1 (−1.4 to 1.2) 1.4 (−2.5 to 0.3) −0.1 (−1.1 to 0.9)
633−1.6 (2.2) 28 −1.1 (2.0) 29 –1.8 (2.1) −0.4 (−1.8 to 1.0) 0.2 (−1.1 to 1.6) −0.7 (−1.7 to 0.3) 0.2 (−0.7 to 1.2)
733−1.8 (2.4) 24 −0.6 (2.1) 29 –1.3 (2.1) −1.2 (−2.7 to 0.09) −0.5 (−1.9 to 0.9) −1.4 (−2.6 to −0.2) −0.5 (−1.6 to 0.6)
833−2.2 (2.4) 24 −0.7 (1.5) 27 –2.9 (2.2) −1.5 (−2.8 to −0.1) 0.7 (−0.7 to 2.0) −1.5 (−2.5 to −0.5) 0.6 (−0.4 to 1.6)
930−2.1 (2.2) 23 −0.5 (2.2) 26 –2.6 (1.2) −1.7 (−3.1 to −0.2) 0.4 (−1.0 to 1.7) −1.8 (−3.0 to −0.6) 0.4 (−0.7 to 1.5)
10 30 −2.4 (2.5) 22 −1.0 (1.6) 26 –2.8 (2.2) −1.5 (−2.9 to 0.07) 0.4 (−1.0 to 1.8) −1.4 (−2.5 to −0.3) 0.4 (−0.6 to 1.4)
n = number of participants. Values are presented as mean ± SD. Boldface indicates significant differences. Adjusted for age, sex, and baseline crying time.
604 Journal of Manipulative and Physiological TherapeuticsMiller et al
October 2012Chiropractic for the Excessively Crying Infant
treatment effect might therefore be reconsidered in the light
of this finding. The only other study
15
in which parents were
blinded reported no differences in effect between groups.
Possible explanations for differences in the findings from
this study and the one reported here include differences in
treatment and control groups (their participants underwent
motion palpation and holding/soothing, whereas our control
group did not receive any clinical handling) and in the
primary outcome measure. Moreover, it is likely that the
study of Olafsdottir et al
15
included more infants at the
severe end of the crying spectrum (as all had been previously
treated unsuccessfully in the health care system), and the
analysis did not account for the large dropout in the control
group, which may have included the highest criers, as other
studies show.
13,33
All dropouts in this study occurred in the no-treatment
group, which has also been shown to be the case in other
studies.
13,33
Although the parents of these infants were
apparently “blind”to the treatment group, we can speculate
that any lack of improvement deterred parents from
returning to the clinic. Alternatively, these parents may
have correctly guessed that their child was not being treated
and left the trial to be treated elsewhere. This is supported
by our findings of no difference between the treatment
groups in which parents were blinded and not blinded to
treatment. We found a clinically significant effect of
chiropractic manual therapy in this patient group but,
importantly, that this is evident despite whether or not
parents know their child was treated. We can conclude that
any reporting bias by the parent was not responsible for the
observed effect of treatment in this study.
A relatively low number of parents (n = 5 [15%])
reported that their child was not treated in the NTB group. It
is also true that this was greater in the TB group, where 17
(49%) of the parents considered that either their child was
not treated or they did not know. One reason for this is that
we are, of course, not comparing like with like because the
second is a composite figure. In addition, the 9 who
dropped out in the NTB group might be assumed to have
done so because their babies were not being treated. If this
assumption were true, this would raise the number of
patients who were not being treated to 14 (41%). When
combined with the number of parents who did not know
(20; 59%), this would bring the total to 100% compared
with the 48% in the TB group, in line with what might
be expected.
Limitations
This randomized trial did have limitations that caution
interpretation of the findings, not least conducting a trial in a
routine practice setting and the consequential problems of loss
to follow-up. This was compounded by the fact that we
decided, for ethical reasons, to discharge patients who were
recovered early on in the trial.
34
Together with small sample
sizes from the outset and variability within our data sets, this
meant that estimates of effects in the target population were
imprecise, thus compromising, at least in part, their clinical use.
Although we paid particular attention to blinding the
parents, it was not possible to exclude the parent from the
treatment room altogether because of regulations governing
chiropractic treatment for minors in the United Kingdom.
Moreover, we only checked parents for blinding at the end
of the study. By asking parents to state whether or not they
thought their child was being treated, it was inevitable that
any change in their child's condition by the end of the
treatment period would have influenced their decision.
Thus, we did not know the parents' “beliefs”day by day
throughout the study period at times when they were
completing the crying diary. Furthermore, as a single-blind
trial, we only attempted to blind the parents. It was
Table 3. Mean change in crying times (in hours per day; adjusted data)
Improvement Days
Proportion
improved
(%), T(B) NT(B)
Crude OR
(95% CI),
T(NB) T(B) vs NT(B) NNT
Adjusted OR (95% CI) *
T(B) vs T(NB)T(B) vs T(NB) T(B) vs NT(B)
(i) ≤2-h crying
per day
2 8.6 9 12.5 0.9 (0.2-5.0) –1.5 (0.3-7.4) 0.8 (0.1-8.9) 2.0 (0.3-12.8)
4 11.4 6.4 12.9 1.9 (0.3-11.0) –1.1 (0.3-5.0) 1.9 (0.2-15.0) 1.1 (0.2-5.6)
6 27.3 14.3 20.7 2.2 (0.6-8.3) –0.7 (0.2-2.3) 2.3 (0.5-10.4) 0.7 (0.2-2.3)
8 45.4 12 37 6.1 (1.5-24.4) 3 0.7 (0.2-2.0) 8.1 (1.4-45.0) 0.7 (0.2-2.0)
10 50 13.6 34.6 6.3 (1.5-26.0) 2.7 0.5 (0.2-1.5) 11.8 (2.1-68.3) 0.5 (0.1-1.6)
(ii) N30% change 2 37.1 24.2 37.5 1.8 (0.6-5.3) –1.0 (0.6-13.6) 2.4 (0.8-8.2) 0.7 (0.3-2.0)
4 40 25.8 29 1.9 (0.7-5.5) –0.6 (0.2-1.7) 3.8 (0.9-15.1) 0.3 (0.1-1.0)
6 51.5 46.4 62.1 1.3 (0.4-3.4) –1.5 (0.5-4.2) 1.1 (0.4-3.3) 1.3 (0.4-3.8)
8 63.6 24 63 5.5 (1.7-17.6) 2.7 1.0 (0.3-2.8) 4.9 (1.5-16.3) 0.7 (0.2-2.1)
10 63.3 31.8 73.1 3.7 (1.1-11.8) –1.6 (0.5-4.9) 2.8 (0.8-9.3) 1.1 (0.3-3.7)
(iii) GIS 10 82.3 11.1 93.7 37.3 (8.4-165) 1.4 3.2 (0.6-17.3) 44.3 (7.7-253) 1.9 (0.4-9.0)
Participants categorized as improved based on (i) less than 2 hours of crying per day, (ii) more than 30% change from baseline, and (iii) scoring 4 or 5 on
the GIS. Boldface indicates significant differences.
OR, odds ratio.
⁎Adjusted for age, sex, and baseline crying time.
605Miller et alJournal of Manipulative and Physiological Therapeutics
Chiropractic for the Excessively Crying InfantVolume 35, Number 8
obviously not possible to blind those administering the
treatment, and thus, the findings of this study may be
subject to practitioner bias. The practitioners in this trial had
no part in reporting outcomes from care.
External validity is often problematic in randomized
trials, and this study is no exception. Infants were treated in
an outpatient teaching clinic by different final-year student
interns accompanied by experienced clinicians. This does
not reflect treatment that is received in established
chiropractic practices. Similarly, most parents were referred
by general practitioners, midwives, and health visitors in
the area, and in many cases, parents expected to pay for
treatment. Whether our sample represents the population of
parents of infants with excessive crying symptoms is
therefore questionable. Moreover, the inclusion criterion
that allowed for the mother's diagnosis of excessive crying
is a subjective one, although paradoxically, this may
increase the generalizability of the findings and all infants
did fit the routine definition of colic for amount of crying
previously shown in the research.
1-3,25-29
Also, diary
information and parental reporting of accurate time crying
may be subject to recording error or bias.
Finally, we used 2 cutoffs in the change in crying time
with which to categorize improvement in our participants.
The more conservative of these was 2 or less hours per day
of crying, which has been reported in the literature as a
“normal”level of crying.
24,35
The other cutoff of more than
30% reduction in crying was entirely arbitrary on our part
and is open to challenge. However, we felt it necessary to
define these end points to report the findings in clinically
significant terms rather than as group mean statistically
significant decreases in crying time that are more difficult to
interpret from a clinical perspective. Both cutoff points
were chosen for the practical reason to increase the
robustness of the clinical results because cutoff points can
be considered arbitrary. We did not mix the cutoff points
but purposely kept them separate, to address any criticism
concerning an idiosyncratic cutoff point.
CONCLUSION
In conclusion, the findings of this study demonstrate a
greater decline in crying behavior in colicky infants treated
with chiropractic manual therapy compared with infants
who were not treated. The findings also showed that
knowledge of treatment by the parent did not appear to
contribute to the observed treatment effects in this study.
Thus, it is unlikely that observed treatment effect is due to
bias on the part of the reporting parent.
FUNDING SOURCES AND POTENTIAL CONFLICTS OF INTEREST
A research assistant was partially funded by the British
Columbia Chiropractic Association. Tomy Toy Company
donated a cuddly toy to each infant at exit of the trial. No
conflicts of interest were reported for this study.
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