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PEDIATRICS Vol. 108 No. 4 October 2001, pp. 893-897
From the * Netherlands Organisation of Applied Scientific
Research (TNO) Prevention and Health; Leiden; and Objective. To assess the
impact of varying definitions of excessive crying and infantile colic
on prevalence estimates and to assess to what extent these definitions
comprise the same children.
Methods. Parents of 3345 infants aged 1, 3, and 6 months
(response: 96.5%) were interviewed on the crying behavior of their
infant in a Dutch cross-sectional national population-based study. We computed the prevalence of excessive crying according to 10 published definitions regarding parent-reported duration of infant crying and the
parents' experience. We measured concordance between pairs of
definitions by Cohen's Results. Overall prevalence rates of excessive crying
varied strongly between definitions, from 1.5% to 11.9%. They were
always highest in 1-month-old infants. Concordance between definitions
was only excellent ( Conclusions. Different definitions of excessive crying
lead to the inclusion of very dissimilar groups of infants. We
recommend presenting study results using clearly described definitions,
preferably concerning both duration of crying and parental distress.
This may improve the comparability of studies on the cause and
treatment of excessive infant crying. The impact of the method of data
collection on this comparability needs additional study.colic, preventive child health care, prevention, infancy.
Vrije Universiteit
Amsterdam, Faculty of Medicine, Department of Social Medicine,
Amsterdam, The Netherlands.
ABSTRACT
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Abstract
Methods
Results
Discussion
Conclusion
References
(agreement adjusted for chance agreement).
> 0.75) if they were closely related,
such as crying for >3 hours/day for >3 days/week for the preceding 2 or 3 weeks. Concordance between less closely related definitions was
much weaker. Concordance between definitions that were based on
duration and on parental experience was mostly poor (: 0.17-0.53
for infants aged 1 and 3 months).
Excessive crying of young infants is a common and often
serious problem for parents.1,2 As such, it may affect
parental feelings negatively and may cause the infant to be regarded as
vulnerable or difficult.1,3,4 It also may distort the
future relationship between parent and child,5 although
evidence pointing this way is not conclusive.1,6 Furthermore, parents may undertake all kinds of actions to stop excessive infant crying. Some of these may be detrimental to the infant's health1,7 such as slapping or shaking the
child.8
Despite its potentially substantial negative health
consequences, no consensus has been reached on the definition of
excessive crying, often called "infantile colic."1,4
The available definitions mostly concern the duration of infant crying or its effect on the parents. Regarding duration, an often-cited definition is that of Wessel et al, published in 1954,9 which distinguishes between "fussy" and "seriously fussy"
children:
"A `fussy' infant was defined as one who, otherwise healthy and
well-fed, had paroxysms of irritability, fussing or crying lasting for
a total of more than three hours a day and occurring on more than three
days in any one week." (pp. 425-426)
" `Seriously fussy,' in that their paroxysms continued to recur
for more than 3 weeks, or became so severe that the pediatrician felt
that medication was indicated (footnote: It is the authors' opinion
that these `seriously fussy' infants would be classified as
`colicky' by most pediatric observers.)." (p. 427)
This Wessel definition often is used110-14 but regularly
with modifications that may lead to different
findings.10,11 Lehtonen and Korvenranta,11
for instance, operationalize it as "paroxysms of crying for 3 or more
hours per day for 3 days or more per week during a period of at least 3 weeks" (p. 534). Although any cutoff point is
arbitrary,1 the use of "3 or more" in 2 instances
instead of "more than 3" probably will lead to the inclusion of a
larger group of children. Other (combinations of) cutoff points
regarding the duration of crying also have been used.5,7,10,1315-22
Regarding the effect of infant crying on parents, a similar variety of
definitions has been used, such as to what extent parents are able to
console their child,7,23 think that their child is
colicky11,24 or cries a lot,7 seek
professional help,1025-27 or experience the crying of
their infant as problematic.19
For a proper interpretation of the various studies on the occurrence,
cause, and treatment of excessive crying and infantile colic,
information is needed to establish to what extent these various
definitions comprise the same children. Unfortunately, little is known
on this subject. A few studies provide prevalence rates based on
several definitions,7,19,27 but only 1 shows the degree to
which various definitions comprise the same children.19
The aim of this study was to assess the impact of the definition on
estimates of the prevalence of excessive crying and to assess to what
extent various definitions comprise the same children.
Sample and Procedure
Trained child health professionals (physicians and nurses)
interviewed a national sample of parents on their infants' crying behavior and on background characteristics, from October 1997 to June
1998. The sample was obtained using a 2-step procedure. In the first
step, a random sample of 16 of 65 Well Infant Clinics was drawn, after
stratification by region and degree of urbanization of their district.
In the second step, each clinic provided a random sample of 75 infants
for 3 age groups (variation allowed between brackets): 4 (±1), 13 (±2), and 26 (±4) weeks, further called 1, 3, and 6 months. Of the
3467 eligible children, 96.5% (n = 3345) participated.
The main reason for nonresponse was lack of interest in the object of
study. The sample was representative of the entire Dutch population,
except that infants who lived in big cities were relatively
underrepresented as a result of the sampling procedure.
The data were collected in a standardized way as part of the preventive
health assessments to which all Dutch children are invited regularly.
Before the assessment, information on the study and a questionnaire on
parental actions regarding crying were mailed to all parents. The
design of the study was approved by the Medical Ethical Committee.
Data and Measures
All questions on crying referred to infant crying in the period
just before the interview: mean duration per day during the last week
(=7 days), number of days during the last week in which the crying
lasted longer than 3 hours, number of successive preceding weeks in
which the duration of crying exceeded 3 hours, parental opinion on
crying at present (cries a lot: yes/no; if yes, to what extent is it a
problem: never/at least sometimes), consolability if crying (easy or
difficult), and consultation of a health professional for the crying of
this infant (yes or no). On the basis of this, 10 definitions that had
been used in previous studies were operationalized (see Table
1). All definitions regarding duration
were applied only to crying and not to fussing,1 as
differences between definitions regarding this would confound our
results.
TABLE 1
METHODS
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Abstract
Methods
Results
Discussion
Conclusion
References
Definitions of Excessive Crying Used in This Study
Data Analysis
We first computed the prevalence rates of excessive crying
according to the various definitions and the mean number of hours of
crying per day during the preceding week by children who met the
criteria of that definition. Next, in a pair-wise analysis, we compared
the definitions regarding the percentages of all infants that were
comprised by them. We then computed Cohen's statistics (agreement
adjusted for chance agreement)28-31 to measure
concordance between pairs of definitions. Fleiss characterized of
0.75 and over as excellent, below 0.40 as poor, and those in between as
reasonable to good.28 We computed for the 1- and
3-month age group and for the 6-month age group separately because
infants with persistent excessive crying beyond 4 months of age may
constitute a different clinical entity.1,4,32 Finally, we
assessed the impact of differences in prevalence between raters (ie,
definitions) and of a low overall prevalence,33,34 as both
may influence the values of .29,34,35
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RESULTS |
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Results
Discussion
Conclusion
References
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Overall prevalence rates of excessive crying differed strongly between definitions, although, in general, they were highest among 1-month-old infants (Table 2). Infants who met the criteria of a definition always cried more hours per day than the other infants with statistical significance.
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As was expected, concordance between definitions was excellent
( > 0.75) when it concerned closely related definitions, such as crying >3 hours/day on >3 days/week for at least 3 weeks and for
>3 weeks. However, concordances between duration-based definitions on
the one hand and parental experience-based definitions on the other
hand were, at best, reasonable but often poor. Furthermore, the mutual
concordance between duration-based definitions decreased rapidly when
they were less closely related. Finally, the concordance between a
definition that was based on the consolability of the infant and all
other definitions generally was poor.
The additional analyses regarding the 6-month age group showed that
almost all were much lower for this group than for the 1- and
3-month age groups combined, indicating poor concordance, except for
the aforementioned closely related definitions. Therefore, in Table
3 we present for the combined 1- and
3-month age group only and mainly for definitions for which high cannot a priori be expected. Because of the low prevalence of excessive crying at the age of 6 months, were only slightly different when we
also included the 6-month age group.
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The impact of differences in prevalence on the values of was small;
absolute values of Byrt's bias index34 was always 0.12 or
less. The impact of a low overall prevalence, however, seems to be
larger; absolute values of Byrt's prevalence index34 varied from 0.76 to 0.95. As a solution for this, Cicchetti and Feinstein33 proposed using the proportion of positive and
negative agreement. The latter is of little interest for this analysis,
because most infants are not excessive criers. (This is reflected by
high proportions of negative agreements, from 0.92 to 1.00.) Resulting
proportions of positive agreement are on average 0.04 higher than
values of , without affecting our findings. Again, results hardly
change when the 6-month-old group is included (not shown).
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DISCUSSION |
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Discussion
Conclusion
References
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Our results show that the overall prevalence rates of excessive
crying vary 8-fold depending on the definition used. Relatively small
differences between definitions seem to cause large changes in
prevalence rates. Furthermore, definitions seem to comprise different
groups of infants as is shown by generally low statistics, except
when these definitions are closely related.
Bias can hardly explain our findings. First, our sample was
representative for almost all Dutch infants and response rates were
very high (96.5%). Second, information regarding all definitions was
obtained in a similar way. Thus, although retrospective parental report
may give other estimates of infant crying than prospective parental
report (eg, diaries) or tape registration,1736-38 this
will hardly affect the comparison between the various way of measuring
duration. Regarding our comparison of duration and parental
experiences, however, we expect some overestimation of concordance, as
parental feelings will influence both factors. This suggests that the
actual might even be lower than the already low ones that we found;
this topic deserves additional study. Finally, neither the differences
in prevalence rates on the basis of the various definitions nor the
overall low prevalence rates affected our results in a systematic way.
As to prevalence rates, our results show that even small changes in the
definition of excessive crying have considerable consequences. For
instance, regarding the duration of crying, application of the exact
Wessel definition of colic (crying >3 hours/day on >3 days/week for
>3 preceding weeks)9 yields a prevalence rate of 1.5%.
When the last part of this definition is relaxed to "for 3 or more
preceding weeks,"22 to "for 2 or more preceding
weeks,"21 or to "during the preceding
week,"9 this adds 0.6%, 1.0%, and 2.6%, respectively,
to the prevalence rate. When the second part of the definition also is
slightly relaxed, from ">3 days/week" to "
3
days/week"10 this again adds 1.7%. In total, this more
than quadruples prevalence rates (from 1.5% to 6.4%). Prevalence
rates thus can be compared only when the definitions that were used are
completely comparable.
Our combined data on prevalence rates and concordance show that
different definitions often yield different prevalence rates and that
even if prevalence rates are similar, they may concern different
children. As such, our study provides a quantification of a problem
already noted by other authors.1,4,7,19,27 For instance,
the definitions "crying for >3 hours/day on 3 or more days during
the preceding week," "crying on average 3 or more hours/day during
the preceding week," and "inconsolable crying" yield similar
prevalence rates for infants aged 1 and 3 months (8.8%, 8.1%, and
8.0%, respectively). However, only the first 2 definitions comprised
mainly the same children (10.4% of all infants are comprised by at
least either of them, 6.3% by both). The other 2 combinations of
definitions jointly comprised only approximately 1 quarter of the
infants that were comprised by either of them (which was reflected by a
very low ). When 6-month-old infants also were taken into account,
results were even worse (not shown).
Thus, the results of studies that use different definitions cannot be compared because they mostly concern different infants. This is relevant for both etiologic studies and studies on the effectiveness of treatments. For instance, the varying results of trials on various behavioral interventions25,2639-41 may be due, at least partially, to differences in the kind of crying infants that were included.40 Our results further support previous reports that infants who cry excessively beyond 4 months of age may constitute a different group.1,4,32
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CONCLUSION |
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The results of our study emphasize the necessity to use better comparable definitions in studies on excessive crying and colic. A presentation of results using several clearly described definitions might serve this purpose. It remains to be decided which definitions one should use. We presented results on 10 definitions, but many more could be extracted from the literature. Preferably, studies should use both a definition regarding the duration of crying and fussing per day and one regarding the resulting parental distress. Regarding duration, adherence to the original definitions made by Wessel et al may be useful. These are very widely known1,14 and enable a discrimination between crying a lot (crying >3 hours/day on >3 days, ie, at least 4, in the preceding week)9 and excessive crying (meeting this criterion for >3 successive weeks).9
Second, inclusion of a definition that concerns parental distress is important, as this is a main impetus for seeking professional care,4 like that on problematic crying as defined by Canivet et al.19 Many additional factors influence the composition of this group, however, such as parental background12,42 and kind of care setting (eg, community care vs specialist referral care).1,4,43 In a clinical setting, diaries 27,36,38 are necessary when interventions are considered. In that case, the second Wessel definition may be of less interest, as parents or clinicians may not be willing to wait for 3 weeks.1
Finally, in all cases, a clear description of the applied definition is very important as even minor deviations may lead to the inclusion of different groups of infants. The same holds true for the way in which data are collected (eg, diaries, retrospective self-report, audiotapes).2736-38 We hope that this advice will be a step toward more insight into the causes and treatment of excessive infant crying.
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ACKNOWLEDGMENTS |
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This study was supported by grants from the Dutch Ministry of Public Health and the Praeventiefonds (Grant 28-2628-1).
We thank the personnel of the 16 Dutch Well Infant Clinics who participated in this study.
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FOOTNOTES |
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Received for publication Jul 25, 2000; accepted Jan 29, 2001.
Reprint requests to (S.A.R.) Netherlands Organisation of Applied Scientific Research (TNO) Prevention and Health, Box 2215, 2301 CE Leiden, The Netherlands. E-mail: sa.reijneveld{at}pg.tno.nl
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REFERENCES |
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maternal fantasies of
aggression and infanticide.
Clin Pediatr (Phila)
2000;
39:395-400 This article has been cited by other articles:
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  R. von Kries, H. Kalies, and M. Papousek Excessive Crying Beyond 3 Months May Herald Other Features of Multiple Regulatory Problems Arch Pediatr Adolesc Med, May 1, 2006; 160(5): 508 - 511. [Abstract] [Full Text] [PDF]
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 E. D. Shenassa and M.-J. Brown Maternal Smoking and Infantile Gastrointestinal Dysregulation: The Case of Colic Pediatrics, October 1, 2004; 114(4): e497 - e505. [Abstract] [Full Text] [PDF]
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 C Miller-Loncar, R Bigsby, P High, M Wallach, and B Lester Infant colic and feeding difficulties Arch. Dis. Child., October 1, 2004; 89(10): 908 - 912. [Abstract] [Full Text] [PDF]
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S. A. Reijneveld, E. Brugman, F. C. Verhulst, and S. P. Verloove-Vanhorick Identification and Management of Psychosocial Problems Among Toddlers in Dutch Preventive Child Health Care Arch Pediatr Adolesc Med, August 1, 2004; 158(8): 811 - 817. [Abstract] [Full Text] [PDF]
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 A. K C Leung and J. F. Lemay Infantile colic: a review The Journal of the Royal Society for the Promotion of Health, July 1, 2004; 124(4): 162 - 166. [Abstract] [PDF]
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S A Reijneveld, E Brugman, and R A Hirasing Excessive infant crying: definitions determine risk groups Arch. Dis. Child., July 1, 2002; 87(1): 43 - 44. [Abstract] [Full Text] [PDF]
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D. Duro, R. Rising, M. Cedillo, and F. Lifshitz Association Between Infantile Colic and Carbohydrate Malabsorption From Fruit Juices in Infancy Pediatrics, May 1, 2002; 109(5): 797 - 805. [Abstract] [Full Text] [PDF]
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