The Crying of Infants With Colic: A Controlled Empirical Description

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The

Crying

of Infants

With

Colic:

A Controlled

Empirical

Description

Ronald G. Barr, MA, MDCM, FRCF(C)*; Audrey Rotman;

John Yaremko, MDCM, FRCF(C)*; Denis Leduc, MD, FRCF(C)*; and

T. Emmett Francoeur, MDCM, FRCP(C)*

ABSTRACT. To obtain a controlled empirical description of some of the measurable clinical features of colic in a naturalistic context, 38 infants whose mothers considered

crying a problem (“colic”) and 38 pair-matched control

infants were observed and videotaped at home 10

mm-utes before and after an evening feed. The parents kept a diary of infant behaviors (including crying and fussing) for 7 days following the visit. Following Wessel et al (Pediatrics. 1954;14:421-434), each “colic” infant was

clas-sified according to the number of days per week that

crying and fussing duration was greater than 3 h/d. The distribution of infants with colic suggested that there were two subgroups: Wessel’s colic infants, with 3 days

or more per week of more than 3 hours of crying and

fussing per day; and non-Wessel’s colic infants, with

fewer such days. Maternal measures of total daily

crying/fussing duration, crying/fussing bout length, and infant temperament and objective analyses of facial ac-tivity showed a consistent pattern of differences in which Wessel’s colic infants differed from both non-Wessel’s colic and control infants, who in turn did not differ from each other. Both colic groups differed from control in-fants only in the perception of postfeed cries as being more “sick sounding.” The results imply that the corn-plaint of colic represents two (or more) groups and that there may be meaningfully distinct colic syndromes. They also provide the first independent empirical sup-port for Wessel and colleagues’ clinical distinction

be-tween “fussy” and “contented” babies. Pediatrics

1992;90:14-21; colic, crying, fussing, infant, temperament.

Despite its clinical salience, there is little consensus as to what constitutes the clinical entity of “colic.’ Indeed, it is not particularly clear whether colic should be considered as a complaint or a syndrome.1’2 In a recent review,’ clinical phenomena which were taken as evidence for the presence of colic varied widely. The only generally accepted symptom was crying or

fussing which was in some sense “excessive,’ being

explicitly mentioned by approximately 80% of the authors. However, there was little agreement on the amount and/or timing of the crying. Other

phenom-From the Departments of 5Pediaincs and Psychiatry, McGill University and the §McGill University-Montreal Children’s Hospital Research Institute, Montreal, Quebec, Canada.

Received for publication Aug 26, 1991; accepted Dec 12, 1991.

Presented, in part, at the combined meetings of the Ambulatory Pediatric Association and the Society for Pediatric Research, New Orleans, LA, April

30 and May 1, 1991.

Reprint requests to (R.G.B.) Montreal Children’s Hospital, 2300 rue Tupper, Montreal, Quebec, Canada H3H 1P3.

ena frequently noted included the crying being “par-oxysmal’ (42%), the infant being otherwise well (30%), the infant experiencing pain or manifesting a pain facies (26%), unresponsiveness to soothing in-tervention or feeding (24%), and presence of gastroin-testinal symptoms (gas, 30%; distention, 10%; fre-quent stools, 6%; vomiting or regurgitation, 6%).

Delineation of a colic syndrome is made more dif-ficult by similarities between the crying behavior of infants with and without colic.3 In particular, daily duration of crying in normal infants tends to increase until the second month of life and cluster during the evening hours,47 a pattern typically reported for in-fants with colic.8” This has understandably raised the question as to how much crying is “normal’ and whether the crying of colic is distinctly different or simply the upper end of a spectrum of otherwise normal crying.3

The most widely cited criteria were described by Wessel and his colleagues in 1954 on the basis of a careful, systematic study of infants from The Yale

Rooming-In Project.8 Commonly known as “the rule

of 3’s,’ they defined a “fussy’ infant as “one who,

otherwise healthy and well-fed, had paroxysms of

irritability, fussing or crying lasting for a total of three hours a day and occurring on more than three days in any one week.’8425426 An infant was “seriously fussy’ if, in addition, “their paroxysms continued to recur for more than three weeks, or became so severe that the pediatrician felt that medication was mdi-cated.’8427 Because few parents or physicians are willing to permit observation without intervention for

3 weeks, in practice and in most studies the “three

week’ criterion is dropped and/or the intervention

criterion is used. Wessel et a! did not argue that this

definition is anything other than an arbitrary and

convenient cutoff point for the purposes of comparing

“fussy’ with “contented’ infants. Indeed, they noted that “the time distribution and frequency of diurnal regularity are similar for the mild fussy periods of the ‘contented babies,’ and for the more prolonged pe-riods of the ‘fussy infants.”8 Similar limitations obtain for all other published criteria, and there is no system-atic evidence to date of discontinuity between the crying of infants with and without colic.3 As a result, while Wessel and coworkers’ (and other) criteria have been useful as an “objective’ index of severity of

crying, it is not clear whether they describe a clinically

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28.4 ± 6.3 29 (76) 13 (34) 25 (66) 3458 ± 363

51.0 ± 1.8 35.0 ± 1.3 3982 ± 445 176 ± 76 27.3 ± 10.8

22 (58) 7(18) 7(18) 2 (5) 5(13) 4(11) 2 (5) 32 (84) 8(21) 4(11) 0 (0) 22 (58)

28.5 ± 6.5 30 (79)

17 (45) 21 (55) 3369 ± 457

50.7 ± 2.3

34.6 ± 1.3 3841 ± 560

191 ± 78 31.4 ± 14.7

22 (58) 9 (24) 5(13) 2 (5) 5(13) 2 (5) 0 (0) 36 (95) 4(11) 2 (5) 0 (0) 20 (53)

30.3 ± 3.6 31.0 ± 4.8

33.1 ± 5.5 33.2 ± 5.1

15.5 ± 3.0 15.6 ± 3.3 68.7 ± 7.9 38 (100) 28 (74) 10 (26) 30 (79) 8(21) 4(11) 3 (8)

15.3 ± 2.5 16.1 ± 3.2 67.6 ± 14.0

35 (92) 30 (79) 8(21) 28 (80) 10 (29) 11 (29) I (3) ARTICLES 15

These difficulties in definition have made the

gen-eralizabiity of therapeutic studies difficult to

evaluate’2’4 and have compromised effective clinical approaches to crying problems.3 For example, dietary trials tend to include infants with more severe colic and a higher prevalence of gastrointestinal symptoms

compared to studies of behavioral

interven-tions.’2”3”5’7 Furthermore, most studies have relied solely on parental report, only occasionally supple-mented by observations in the office.

To begin to address these weaknesses, we under-took a controlled, multilevel descriptive study in the home to identify some differences between the crying of infants with and without colic. To avoid the cir-cularity inherent in defining colic a priori in terms of quantity or quality of crying (or other symptoms), we chose by design to consider colic as a clinical corn-plaint. Thus, infants with “colic’ were those whose crying was seen as a problem by mothers and/or fathers. We wished to determine empirically whether these infants differed from those whose crying was not seen as a problem on a number of commonly reported and measurable clinical differences.

Subjects and Procedure

METHODS

The 38 clinical parents and infants were recruited from two

general urban pediatric practices in Montreal, Quebec, Canada.

Subjects were considered eligible if the crying of the infants was

seen as a problem by the parents and the crying problem was a

primary presenting complaint in the normal course of office

prac-rice. Crying seen as a problem included complaints of feeding or

sleeping difficulties where crying was offered as the evidence for those difficulties. Being seen as a problem might include the crying causing anxiety in the mother, concern that the infant was hungry, or arguments with the spouse about appropriate caretaking. Crying was a primary complaint if the visit was requested for that behavior or if the parent raised it spontaneously or in response to an

open-ended question (eg, Are there any problems?). In addition, all

mother-infant pairs had a normal prenatal, perinatal, and postnatal history, no current illness, and a normal physical examination. The 38 control subjects were recruited from the same practices from lists provided by the office staff of infants who recently had visited the office. Infants were picked to be pair-matched for age (within 3 days) and, as closely as possible, for parity (first or greater than first born), maternal language (English or French), and gender. Otherwise they met the same inclusion criteria. Because colic was not defined in terms of amount of crying, infants who cried a lot but whose crying did not concern the mother were not included in the colic group, but neither would they be excluded from the list of infants with recent visits. They would therefore be eligible for the control group. Characteristics of the study sample are summa-rized in Table 1.

Parents who expressed interest in the study were contacted by

the research assistant, the study was described in detail, and arrangements were made for a home visit. To maximize the likeli-hood that the infant would cry, the home visit occurred just before and after an evening feed. On arrival, the research assistant de-scribed the study in detail and obtained informed consent. Prior to the feed, the infant was changed and placed across two firm pillows

on the floor. The lens of a Panasonic AG-170 VHS videocamera

was adjusted to provide a full face and trunk view. Parents and research assistants were out of visual or physical contact. Videotap-ing occurred before and after, but not during, the feed.

The infant was observed for 10 minutes, or until he or she began a‘sustained’ cry, operationally defined as three consecutive inspir-atory-expiratory negative vocalizations. The crying infant was then

observed for 2 minutes. One minute after the cry started, the

mother used rating scales to indicate how the cry sounded to her. At the end of 2 minutes of crying, the infant was picked up, calmed,

fed, and burped. A second observation using the same protocol

TABLE 1. Characteristics of Study Sample5

Characteristic Colic (n=38) Control (n=38) Infant Age, d Parity (first born) Sex

Male Female Neonatal indices

Birth wt, g Birth length, cm

Head circumference, cm

Weight at office visit, g Time since last feed, mm Duration of feed, min

Feeding type

Breast only Formula only

Mixed (1 bottle/d)

Mixed (>1 bottle/d) Night bottle only

Feeding type change during diary week Breast to formula Formula to other formula No change Nonprescription medication use Gripe water Ovol Chamomile tea Pacifier use Farent Age, y Mother Father Socioeconomic indices Education: mother, y Education: father, y Green scores43 Marital status Couples Ethnicity Maternal North American Other Paternal North American Other Parental smoking One Both

5Results are mean ± 1 SD or number of subjects (percent) with designated characteristic in each group.

followed the feed. At the end of the feed, abdominal distention

was measured, demographic and background data were obtained, a measure of early infant temperament was completed by the

mother, and the parents were given a diary with written and verbal instructions which they were asked to complete in the following 7 days.

Measures

Daily Diary. Following Wessel et al,8 the Baby’s Day Diary was used to assess the number of day (0 to 7) of crying and/or fussing for greater than 3 hours. In addition, it provided measures of daily total crying/fussing duration (hours per day), frequency (bouts per day), and bout length (minutes) based on the mean of 7 days of recording. The diary has been previously described, and it provides measures for five infant behaviors, including crying and fussing, and three caretaker activities.5’8 Crying/fussing duration is the arithmetic sum of crying and fussing duration; crying/fussing

fre-quency includes all crying and fussing bouts, but adjacent bouts

are counted as a single crying/fussing bout. Previous comparisons at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

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As expected, there were no significant differences between parents or their infants with and without crying problems on basic demographic characteristics (Table 1). Nor were the groups different on charac-teristic feeding practices, use of common nonmedical soothing techniques, parental smoking, or proximity and duration of feeds at the time of recording. Con-sequently, it is unlikely that these characteristics af-fected observed differences between the groups.

Given the lack of evidence of discontinuity between the crying of infants with and without colic,3 the distribution of infants by the number of days of crying greater than 3 h/d was unexpected (Fig 1). In the control group, the distribution showed a single peak at 0 days, since most of these infants (26, or 72%) never cried more than 3 h/d. Nevertheless, two of these infants did cry this much for 4 days, and one for 7 days. By contrast, the distribution in the colic group appears to show two peaks, with a concentra-tion of infants with no days of prolonged crying and a concentration with 3 days of crying more than 3 hours. Prior to the 3-day peak, the distribution of infants with colic seems to be similar to that of infants without colic.

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NUMBER OF DAYS 3 HOURS CRY/FUSS

with 24-hour audiotaped recordings indicated moderate to strong correlations between duration of audiotaped negative vocalizations and crying duration, and frequency of audiotaped negative vocal-ization bouts and crying/fussing frequency.’8’ Separate measures of crying and fussing durations, frequencies, and bout lengths were

also derived, but since the patterns were in all respects parallel to the findings for crying/fussing measures, they will not be further reported.

The diary also permitted parents to record the daily frequency

of five vegetative behaviors: hiccups, bowel movements,

regurgi-tation, vomiting, and tremors.

Crying After the Feed. Because infants with colic are often

de-scribed as ‘always hungry’ or ‘not quieted with feeding,’ each

infant was classified as to the presence or absence of crying for 2 minutes after the feed.

Distention. Abdominal circumference and skinfold thickness at the umbilicus were measured in triplicate. As an index of distention, the means of these measures were used to calculate fat-free abdom-inal girth (FFAG; in centimeters) according to the formula:

I

[mean circumference]

FFAG = r Xi I I- mean skinfold (cm)

IL ir J

Temperament. Parental perception of infant temperament was as-sessed with an early infant temperament inventory, an adaptatio&9

of the Modified Carey Infant Temperament Questionnaire

prey-ously described by Sostek and Anders.2#{176} The scale consists of 17

items, for each of which there are three possible choices of response

(eg, ‘During sleep, does he or she: a. move about; b. generally lie still; or c. something in between?’). As used here, the inventory

provides a summary score of overall temperament ranging from

-17 (‘difficult’) to +17 (‘easy’), as well as four subscores for regularity, reactivity to physical stimuli, vigor, and squirminess, each including 3 of the 17 items contained in the questionnaire)9

Maternal Perception of Cry Quality. Perceived characteristics of their infants’ crying were rated during the crying bouts before and after the feeding using Zeskind and Lester’s bipolar ratings on each

of eight descriptors of cry quality indicating how urgent, sick, arousing, distressing, discomforting, piercing, aversive, and angry the crying sounded.2’ Ratings ranged between 0 and 7 on a

contin-uous scale, with 7 being more ‘negative.’

Facial Activity During Crying. Facial characteristics during crying

were coded using an adaptation of the Neonatal Facial Coding

System.2223 Each of nine facial actions (brow bulge, eye squeeze, nasolabial furrow, open lips, vertical mouth stretch, horizontal

mouth stretch, taut tongue, pursed lips, and chin quiver) was

counted as present or absent for each of the 1 20 one-second

intervals of the crying bout. Because pursed lips and chin quivers occurred rarely (<1%), they will not be reported. Mean interrater reliabilities estimated by the ic statistic for the other facial actions

averaged .68 and ranged from .46 for horizontal mouth stretch to

.88 for open lips.24

Rates of occurrence per 1 20 seconds were derived for each facial action. In the case of missing intervals due, for example, to the view being blocked by a hand or an arm, rates of occurrence were prorated to 120 seconds. The summary Total Facial Activity score was derived from the mean of the rates of the seven individual

facial actions. Because the crying of infants with colic is often

interpreted as indicating a pain experience,’’225 a Pain

Concaten-ation score was also derived, being the rate of simultaneous

occur-rence of brow bulge, eye squeeze, nasolabial furrow, and open lips.

These facial actions are characteristic of, though not specific for, the infant response to acute nociceptive stimuli.23’2628

Data Analysis

Research assistants entered the diary data into a predefined counting and data reduction software program designed for pre-vious studies using this instrument.5’29 Interrater reliabilities for diary counts of duration and frequencies of crying and fussing following transfer were all >97 and averaged .99 (Pearson corre-lation coefficients). Two subjects (5%) in the control group and one colic subject (2.5%) were missing complete diaries.

Group differences for categorical variables were compared by x2 statistics. Group comparisons for continuous variables used tests of the means of two independent samples or one-way analysis

of variance when three groups were compared, with post hoc

comparisons for location of significant differences between groups where appropriate. On the parent perception and facial measures,

analyses include only those subjects who cried during the

obser-vation session. In addition, videotapes of two control and three

colic subjects were missing because of technical failure. In these cases, the number of subjects entering the analysis is indicated.

RESULTS

Fig 1. Distribution of control (open squares) and colic subjects

(circles) by number of days of crying/fussing totaling more than 3

h/d in 1 week. Colic infants with equal to or greater than 3 such days are designated Wessel’s colic (closed circles); those with less than 3 such days are designated non-Wessel’s colic (hatched

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ARTICLES 17

These distributions suggested that the colic group may be constituted of two subgroups. Consequently, we elected to compare the control group with both the group whose prolonged crying occurred on 2 days or less and the group whose prolonged crying oc-curred on 3 days or more. Although not exactly similar to Wessel and colleagues’ criteria (they specify more than 3 days8), the similarity prompted us to label these groups as “non-Wessel’s colic’ (n = 24, or 65% of the problem crying sample) and “Wessel’s colic’ (n

= 13, or 35%) infants, respectively.

On clinical characteristics (Table 2), the Wessel’s colic group was more likely to cry after the feed (92%) than either the non-Wessel’s colic (71

%)

or control subjects (70%), but this difference was not statistically significant

(x2

= 2.34; P =

.31).

Similarly, there were no group differences in measured distention (fat-free abdominal girth: F = .94; df 2,69; P = .40). There was one difference on vegetative symptoms. Wessel’s colic

infants had more frequent vomiting than

non-Wes-sel’s colic infants, but there were no other group

differences on frequency of hiccups, regurgitation, bowel movements, or trembling episodes.

The groups differed on some, but not all, of the crying/fussing measures recorded in the diary (Fig 2). Notably, the total daily crying/fussing duration of Wessel’s colic infants averaged 4. 1 h/d, about 2’/2 times longer than the control group. In clear contrast, however, the non-Wessel’s group averaged 1 .7 h/d, identical with that of the control group (1.7 h/d). The Wessel’s colic group differed significantly from both

the non-Wessel’s colic and control groups, neither of which differed from each other. However, this pattern did not occur with bout frequency, where there was no significant difference between the groups. Rather, the overall crying differences were due specifically to differences in bout length; bouts were significantly longer in the Wessel’s colic infants (38 minutes) than in either the non-Wessel’s colic (23 minutes) or control infants (1 7 minutes). Bout lengths were not signifi-cantly different between non-Wessel’s colic and con-trol infants. The pattern of differences was essentially identical for measures of crying and fussing consid-ered separately.

A similar pattern was seen for maternal temperament ratings. On the summary score (Fig 3, A), Wessel’s colic infants were rated as significantly more negative (mean = -5.2) than both non-Wessel’s colic (-0.7) and control infants (1 .4), who did not differ from each other. When the subscores were considered sep-arately (Fig 3, B), all four showed significant between-group differences (all P < .05), but the pattern of

differences was not the same for each. Both the

Reactivity and Squirm factors showed a pattern of significant differences clearly similar to that seen for the summary score. For the Regularity factor, the Wessel’s colic score differed significantly only from that of the control group. For Vigor, in contrast, both the Wessel’s and non-Wessel’s colic groups differed

significantly from the control group, but not from

each other.

TABLE 2. Clinical Characteristics5

Feature

Wessel’s

Group Significance

Colic Control

Non-Wessel’s

Crying after feed, % 92

Distention, cm 24.7 ± 6.6

Hiccups, no./d 2.3 ± 1.7

Regurgitation, no./d 2.0 ± 2.0

Vomit, no./d 0.6 ± 1.1

Bowel movements, no./d 3.5 ± 1 .8

Tremor, no./d 0.3 ± 0.5

71 23.6 ± 5.2

1.8 ± 0.9 1.6 ± 1.6 0.1 ± 0.2 3.6 ± 2.1 0.4 ± 1.0

70 22.7 ± 3.3

1.8 ± 0.8 2.0 ± 2.4 0.2 ± 0.2 3.7 ± 1 .9 0.4 ± 0.9

NS NS NS NS .04 NS NS S Results are mean ± 1 SD (except ‘crying a fter feed’). NS, not significant.

Fig 2. Diary measures of crying/fussing behavior. The left panel depicts daily total duration (hours per 24 hours), the center panel daily frequency, and the right panel mean bout length. In this and all subsequent figures, Wessel’s colic infants are represented by closed bars, non-Wessel’s colic infants by

hatched bars, and control infants by

open bars (n

=

13, 24, and 36, respec-tively, for diary data). The F statistic for

the one-way analysis of variance

com-paring the groups is in the upper section of the panel. Starred brackets indicate significant between-group comparisons (555 p < .001; P < .01; P< .05).

B C

at Viet Nam:AAP Sponsored on September 1, 2020

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2,65) 10.4; p< .001

Fig 3. Maternal temperament ratings. Panel A represents the total scores for each group; panel B represents the four subscores of Regularity, Reactivity, Vigor, and Squirm from left to right, respectively. Temperament scores are available for 1 2 Wessel’s colic, 22 non-Wessel’s colic, and 34 control infants. Symbols are explained in the legend to Fig 2.

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The Complaint of ‘Colic’

A B

Group differences for facial activity were compared in those infants who cried before the feed and sepa-rately in those who cried after the feed. After the

feed, there were no between-group differences in

Total Facial Activity, Pain Concatenation, or any of the seven individual facial actions. Before the feed, however, the differences tended to parallel those seen with other measures (Fig 4). Total Facial Activity rates were significantly higher in the Wessel’s group com-pared with those in both non-Wessel’s colic and con-trol infants (78 vs 63 vs 68 occurrences per minute, respectively). Although statistically more suspect (P

= .07), the pattern of differences for Pain

Concaten-ation was essentially the same. Of the individual facial actions, the same pattern of significant differ-ences was obtained for Brow Bulge and Taut Tongue. Similar findings for Eye Squeeze and Nasolabial Fold were almost significant (both P .07).

The maternal perception ratings of the observed crying before and after the feed showed a pattern distinctly different from the other measures. There was no difference on any of the eight descriptors before the feed, nor were there any differences on seven of the eight descriptors after the feed. Mothers’ perceptions differed from each other only on how

sick their infants’ cries sounded after the feed (F =

8.0; df 2,51; P = .001), but in this case, both the Wessel’s colic and the non-Wessel’s colic groups dif-fered from the control group (3.8 vs 3.2 vs 1 .8), but not from each other. When the ratings of those infants who cried both before and after feeds are compared (n = 48; Fig 5), the after-feed cries of both the colic groups are more sick sounding than their own before-feed cries, as well as the cries of the control infants before or after the feeds (group [Wessel’s colic vs non-Wessel’s colic vs controls] X feeding condition [before vs after] repeated-measures analysis of variance in-teraction: F = 3.48; df 2,45; P = .04).

DISCUSSION

The results of this study support the understanding of colic both as a complaint and as a syndrome. When

considered as a complaint, it is apparent that while the amount of crying is relevant, any particular quan-tity of crying is neither necessary nor sufficient to account for its presentation. On the one hand, the group with crying problems did tend to cry more than those whose crying was not a problem. On the other hand, there was considerable overlap in the amount of crying in both groups. In this sample, the amount of crying of fully two thirds of the infants with problem crying was less than a commonly accepted criterion, while the crying of three infants whose crying clearly met those criteria was not seen as a problem.

Consequently, these findings support the principle that any particular amount of crying is not likely to be very helpful in understanding the complaint of colic in the absence of contextual factors.3’3#{176} This is consistent with previous findings that early infant crying functions not so much as a specific identifiable sign, but rather as a graded signal to which the caretaker may react with altruistic, nurturing re-sponses (to relieve the infant’s distress) or egoistic, nonnurturant, and avoidant responses (to relieve the caretaker’s distress) depending on the context in which it occurs.3#{176}In this study, the cries occurring in the context of a recent feed tended to be perceived as more “sick sounding’ by the mothers of both colic groups. It is likely that the prior beliefs of the caretaker contributed to whether the cry was perceived and interpreted as representing hunger or sickness.3033 In the absence of acoustic analyses, it cannot be deter-mined whether the cries themselves were also differ-ent. Nevertheless, this difference in perception is likely to be an index of a different set of beliefs held

by the parents of the infants whose crying was

con-sidered problematic.

The Syndrome(s) of ‘Colic’

The study also provided unexpected evidence that, within the group of colic complaints, there may be two meaningful subgroups or syndromes. One group

would consist of those whose duration and bout

length of crying, temperament, likelihood of crying

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257) =2.86;p= .07

-

--Fig 4. Facial activity rates. The rate of occurrences per 120 seconds during the before-feed crying for Total Facial Ac-tivity (panel A), Fain Concatenation (panel B), and the two statistically

sig-nificant individual facial actions of

Brow Bulge and Taut Tongue (panel C)

are represented. The brackets are inter-rupted for the Pain Concatenation measure because the initial overall analysis of variance did not reach con-ventional significance levels. Symbols are explained in the legend to Fig 2.

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BROW BULGE TAUT TONGUE

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ARTICLES 19

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Fig 5. Parent perception of cry ratings for the dimension of ‘sick-ness.’ The bars represent the maternal ratings before (on the left) and after (on the right) the feed for those infants who cried both times. Group differences between the groups postfeed are indicated by starred brackets. In addition, Wessel’s and non-Wessel’s groups’ postfeed ratings differed from all prefeed ratings in all groups. Symbols are explained in the legend to Fig 2.

after a feed, presence of vomiting, and facial activity when crying are in all respects similar to those seen in normal infants, but whose mothers are nevertheless more concerned about, or less tolerant of, the crying. Other than the specific concern that crying after the feed is more sick sounding, the study does not provide further evidence of the maternal or parental charac-teristics which might contribute to this concern. How-ever, there are a number of likely candidates,

includ-ing postpartum emotional lability and depression or simply not realizing that such crying is typical in the early postpartum period.3437

In the second group (the Wessel’s colic infants), these crying and clinical characteristics are signifi-cantly different from both the control and

non-Wes-sel’s colic infants, and these parents share the belief

that this crying is of concern. The consistent pattern of differences across so many features implies a sys-tematic discontinuity in these characteristics between the Wessel’s colic and both of the other groups, rather than just a gradation of differences between infants who cry less and those who cry more. An alternative hypothesis for the consistency of this pattern is that it simply reflects a systematic reporting bias on the part of the mothers. However, the facial activity measures should not be susceptible to this bias for two reasons: first, facial activity scoring was done independently by research assistants “blind’ to the identity or group assignment of the infant; and sec-ond, only infants who cried are included in the anal-yses of facial activity. Consequently, these are objec-tive differences in the crying of infants with and without colic, not in whether they cried more or less. To our knowledge, the facial comparisons represent the first unbiased empirical evidence of differences in crying between infants with and without colic.

While the facial differences provide important evi-dence of discontinuity, these facial activity features are not specific to Wessel’s colic infants. Although their rates of occurrence were higher, the same fea-tures were also present in both the non-Wessel’s and control groups. Furthermore, the differences were only apparent in the prefeed observation period. Con-sequently, they will not necessarily be characteristic of the crying which occurs in all contexts. It is likely, for example, that the before-feed context represents the summation of two stressors, namely, hunger and separation from the parent, whereas only the sepa-ration stress is present in the postfeed context.

There-fore, such differences may be apparent only at

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“higher’ stress levels, and/or when hunger is a com-ponent of the stress stimulus.

Excessive Crying as Prolonged Crying Bouts

Finally, the diary data support the hypothesis that infants with colic do not just generally cry “more’ than control infants.38 Rather, the distinguishing fea-ture of the “excessive’ crying almost universally re-ported as total daily duration (hours per 24 hours) appears to be bout length. In this study, the bout length in Wessel’s colic infants was almost twice as long (38 minutes) as that seen in the combined control

and non-Wessel’s colic infants (approximately 20

minutes). This relative immutability of bout frequency compared to durational measures was first described in normal infants and cross-cultural samples.5’7’384#{176} For example, despite considerable differences in care-giving style, infants of !Kung San hunter-gatherers cry as frequently but only half as long as is described in comparable observations in Western infants.7’40’4’ The fact that bout frequencies were the same in our study groups despite more than a doubling of overall crying is significant for our understanding of crying in both normal and colicky infants. Because infants with colic represent the extreme of crying in Western societies, these findings extend the range over which the principle of a basic frequency of crying holds. With regard specifically to infants with colic, these findings suggest that putatively successful therapies will be those which effectively interrupt or constrain otherwise typical crying bouts from being prolonged.

Furthermore, shorter bouts, even if frequent, will

probably be associated with less parental anxiety42 and concomitantly fewer complaints.

RELEVANCE AND SPECULATION

These findings have two implications of potential relevance to the clinical presentation of crying com-plaints and colic. The first and most obvious is that, despite previous absence of evidence, it is likely that neither the complaint nor the syndrome of colic is a homogeneous entity. These results suggest that at least two subgroups are discernible in this sample. Furthermore, following current convention, this sam-pie was limited a priori to infants who were “other-wise well.’ While the Wessel’s colic infants did man-ifest slightly more vomiting than non-Wessel’s in-fants, there was no other evidence of increased diarrhea or regurgitation, so that infants with

gas-trointestinal dysfunction were not likely to have been

included. Evidence in the literature suggests that di-etary changes may be useful for small, select groups of infants,’3”6 although the size of the effect is sma1l,’ and the findings are unlikely to generalize to most infants with colic.”3 Such infants might constitute a third subgroup of infants presenting with the com-plaint of colic. It is not possibleto determine whether other subgroups might have been definable in sam-pies from larger groups or different practice settings, or if different measures had been used.

Second, the study provides empirical evidence in support of what practicing physicians have the op-portunity to do daily-namely, careful, systematic, clinical observation. In a review of the literature on

crying and colic, the first author (R.G.B.) wrote that Wessel and colleagues’ criteria were “arbitrary,’ but

that it remained possible “that sensitive

cmi-cians. . .who distinguish the infant with colic are

iden-tifying qualitatively different characteristics which

have escaped systematic investigational

meas-ures.”3’47 Although not put to the test for more than 35 years, the present study implies that Wessel and his colleagues were such sensitive clinicians and that their distinction between “fussy’ and “contented’ in-fants captured a potentially meaningful clinical dis-tinction.

ACKNOWLEDGMENTS

This work was supported, in part, by grants from the Medical

Research Council of Canada (MA-7602 and MA-i 1083), the McGill

University-Montreal Children’s Hospital Research Institute Tele-thon Fund, and the W.T. Grant Foundation Faculty Scholar Award.

We thank Sara J. McMullan and Vina Sweetman for help in

subject recruitment; Roxanne DuBerger and Heinz Spiess, PhD, for the diary counting and data reduction program; Julie Desilets and Jessica Brian for help in data management, statistical analysis, and manuscript presentation; Sara J. McMullan, Kim Burrows, Brian

Katcham, and Manoz Amini for scoring the facial activity; Jim

Hanley, PhD, for a statistical consult; Anton Miller, MD, for a critical review of the manuscript; the office staffs of the participat-ing practices; the mothers and infants who participated in the study; and Dr Morris Wessel for inspiration.

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PROBLEM OF PKU PROGRAM SUCCESS

Pediatricians throughout the 50 states are rejoicing at the remarkable success of a once-revolutionary screening program and diet therapy to prevent mental

retar-dation in the nearly 300 American babies who are born each year with an inherited metabolic disorder called phenylketonuria.

But the doctors are now mobilizing to combat a new problem generated by their very success. They are seeking to prevent mental retardation in the next generation of children, those born to women who have been saved by the original program.

Brody J. A search to bar retardation in a new generation. The New York Times. June 7, 1990.

Submitted by Student

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1992;90;14

Pediatrics

Ronald G. Barr, Audrey Rotman, John Yaremko, Denis Leduc and T. Emmett Francoeur