Basic Clinical Caracteristics of the Participants
| Clinical characteristics | Observed data (n = 368 556) | Weighted data (n = 723 370) |
||||
|---|---|---|---|---|---|---|
| n (%) |
Standardized difference (%) |
n (%) |
Standardized difference (%) |
|||
| Control group (n = 359 769) |
Infantile colic group (n =8787) |
Control group (n = 363 528) |
Infantile colic group (n = 359 842) |
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| Hospital utilization within 6 months of age | ||||||
| Number of visits to pediatricians | 341 551 (94.9) | 8688 (98.9) | 22.5 | 345 435 (95.0) | 342 290 (95.1) | 2.2 |
| Number of visiting ER | 15 903 (4.4) | 1174 (13.4) | 32.3 | 16 843 (4.6) | 18 281 (5.1) | 1.2 |
| Certain conditions (ICD-10 codes) originating in the perinatal period | ||||||
| Respiratory and cardiovascular disorders specific to the perinatal period | 14 605 (4.1) | 427 (4.9) | 4.0 | 14 845 (4.1) | 14 480 (4.0) | 0.1 |
| Infections specific to the perinatal period | 49 707 (13.8) | 1373 (15.6) | 5.3 | 50 342 (13.8) | 51 833 (14.4) | 0.2 |
| Hemorrhagic and hematological disorders of fetus and newborn | 112 149 (31.2) | 2755 (31.4) | 0.2 | 113 338 (31.2) | 112 868 (31.4) | 0.1 |
| Digestive system disorders of fetus and newborn | 10 079 (2.8) | 331 (3.8) | 5.4 | 10 283 (2.8) | 10 410 (2.9) | 0.0 |
| Prevalent diseases (ICD-10 codes) diagnosed within 6 months of age | ||||||
| Otitis media, unspecified | 7989 (2.2) | 204 (2.3) | 0.4 | 8058 (2.2) | 7869 (2.2) | 0.2 |
| Acute nasopharyngitis | 104 381 (29.0) | 3056 (34.8) | 12.5 | 105 974 (29.2) | 107 273 (29.8) | 0.1 |
| Acute pharyngitis | 37 920 (10.5) | 1103 (12.6) | 6.4 | 38 483 (10.6) | 39 901 (11.1) | 0.6 |
| Acute upper respiratory infection, unspecified | 81 665 (22.7) | 2198 (25.0) | 5.1 | 82 711 (22.8) | 84 377 (23.4) | 0.5 |
| Pneumonia, unspecified | 9496 (2.6) | 225 (2.6) | 0.1 | 9569 (2.6) | 10 044 (2.8) | 0.6 |
| Acute bronchitis | 66 304 (18.4) | 1634 (18.6) | 0.6 | 66 995 (18.4) | 66 559 (18.5) | 0.7 |
| Acute bronchiolitis | 48 798 (13.6) | 1129 (12.8) | 2.2 | 49 176 (13.5) | 50 601 (14.1) | 0.7 |
| Viral intestinal infection, unspecified | 9741 (2.7) | 459 (5.2) | 12.5 | 10 064 (2.8) | 11 772 (3.3) | 0.6 |
| Infectious gastroenteritis and colitis of infectious origin | 5416 (1.5) | 192 (2.2) | 5.2 | 5524 (1.5) | 5995 (1.7) | 0.6 |
| Gastroesophageal reflux disease without esophagitis | 8416 (2.3) | 333 (3.8) | 8.6 | 8617 (2.4) | 8590 (2.4) | 0.4 |
| Functional dyspepsia | 7635 (2.1) | 315 (3.6) | 8.7 | 7834 (2.2) | 8289 (2.3) | 0.2 |
| Noninfective gastroenteritis and colitis, unspecified | 16 372 (4.6) | 561 (6.4) | 8.2 | 16 709 (4.6) | 18 306 (5.1) | 0.8 |
| Constipation | 15 365 (4.3) | 574 (6.5) | 9.9 | 15 699 (4.3) | 16 272 (4.5) | 0.7 |
| Functional diarrhea | 5223 (1.5) | 205 (2.3) | 6.1 | 5360 (1.5) | 5375 (1.5) | 0.0 |
| Functional intestinal disorder, unspecified | 10 060 (2.8) | 357 (4.1) | 7.3 | 10 248 (2.8) | 10 274 (2.9) | 0.1 |
| Dermatitis | 15 342 (4.3) | 480 (5.5) | 5.6 | 15 630 (4.3) | 15 785 (4.4) | 0.1 |
| Pyogenic granuloma | 4750 (1.3) | 131 (1.5) | 1.1 | 4820 (1.3) | 4498 (1.3) | 0.0 |
| Urinary tract infection, site not specified | 7731 (2.1) | 231 (2.6) | 3.1 | 7861 (2.2) | 8302 (2.3) | 0.1 |
| Nausea and vomiting | 10 334 (2.9) | 495 (5.6) | 13.6 | 10 699 (2.9) | 11 869 (3.3) | 0.5 |
| Fever, unspecified | 18 237 (5.1) | 524 (6.0) | 4.1 | 18 507 (5.1) | 21 194 (5.9) | 0.1 |
| Drug (drug classification code) used within 6 months of age | ||||||
| Sedative-hypnotics | 10 825 (3.0) | 524 (6.0) | 14.3 | 11 172 (3.1) | 11 444 (3.2) | 0.5 |
| Antipyretics | 126 399 (35.1) | 3410 (38.8) | 7.5 | 127 985 (35.2) | 134 985 (37.5) | 4.4 |
| Antispasmodics | 8222 (2.3) | 638 (7.3) | 23.1 | 8741 (2.4) | 9205 (2.6) | 0.5 |
| Antihistamines | 168 646 (46.9) | 4231 (48.2) | 2.4 | 179 449 (49.4) | 168 537 (46.8) | 0.7 |
| Respiratory system drugs | 195 021 (54.2) | 4905 (55.8) | 3.3 | 197 134 (54.2) | 198 425 (55.1) | 2.8 |
| Digestive system drugs | 188 764 (52.5) | 5899 (67.1) | 30.3 | 191 926 (52.8) | 191 892 (53.3) | 0.8 |
| Hormone drugs | 17 352 (4.8) | 432 (4.9) | 0.5 | 17 530 (4.8) | 16 764 (4.7) | 0.6 |
aUnless otherwise specified, all baseline characteristics were assessed in the first 6 months of age of the participants.
bWeighted using inverse probability of exposure weighting based on the propensity score. The propensity score was estimated using multivariable logistic regression with 97 previously covariates, as defined in Supplementary Table 2 Participants in the reference group were weighted as (propensity score/[1-propensity score]). This method produces a weighted pseudo sample of participants in the reference group with the same distribution of measured covariates as the exposure group.
cResults are reported as n (%) unless otherwise indicated.
dAs the reference group, the control group consisted of children who had not been diagnosed with infantile colic at 5 weeks to 4 months of age.
eThe infantile colic group consists of children who have been diagnosed with infantile colic at least once between 5 weeks and 4 months of age.
fDifferences greater than 10% were interpreted as meaningful differences. All standardized differences in the cohort values were < 0.05.
ICD, International Classification of Diseases; ER, emergency room.