Journal of Neurogastroenterology and Motility : eISSN 2093-0887 / pISSN 2093-0879

Table. 1.

Basic Sociodemographic Characteristics of the Participantsa

Sociodemographic characteristics Observed data (n = 368 556) Weighted data (n = 723 370)b
n (%)c Standardized difference (%)f n (%)c Standardized difference (%)f
Control groupd
(n = 359 769)
Infantile colic groupe
(n =8787)
Control groupd
(n = 363 528)
Infantile colic groupe
(n = 359 842)
Sex
Female 176 967 (49.2) 4331 (49.3) 0.2 178 831 (49.2) 175 873 (48.9) 0.3
Male 182 802 (50.8) 4456 (50.7) 184 696 (50.8) 183 969 (51.1)
Residence at birthg
Seoul 89 501 (24.9) 1977 (22.5) 5.6 90 259 (24.8) 98 793 (27.5) 0.1
Metropolitan 83 324 (23.2) 1656 (18.8) 10.6 83 809 (23.1) 76 547 (21.3) 0.1
Urban 142 540 (39.6) 4031 (45.9) 12.7 144 522 (39.8) 142 079 (39.5) 0.0
Rural 41 184 (11.4) 1021 (11.6) 0.5 41 658 (11.5) 39 266 (10.9) 0.1
Birth weighth (mean [SD], kg) 3.26 (0.36) 3.24 (0.36) 4.6 3.26 (0.36) 3.24 (0.34) 0.1
Type of feedingi
Only breastfeeding 163 567 (45.5) 3745 (42.6) 5.7 165 601 (45.6) 165 291 (45.9) 0.2
Only formula milk 124 583 (34.6) 3344 (38.1) 7.1 126 706 (34.9) 124 049 (34.5) 0.2
Mixed 68 775 (19.1) 1593 (18.1) 2.5 69 773 (19.2) 68 877 (19.1) 0.1
Special milk 1338 (0.4) 72 (0.8) 5.8 1401 (0.4) 1581 (0.4) 0.1
Income quintilej
1 (Lowest) 27 617 (7.7) 683 (7.8) 0.4 27 903 (7.7) 26 791 (7.4) 0.2
2 52 574 (14.6) 1334 (15.2) 1.6 53 143 (14.6) 54 083 (15.0) 0.1
3 (Middle) 95 514 (26.5) 2354 (26.8) 0.5 96 534 (26.6) 96 592 (26.8) 0.0
4 113 679 (31.6) 2792 (31.8) 0.4 114 922 (31.6) 113 306 (31.5) 0.1
5 (Highest) 58 181 (16.2) 1336 (15.2) 0.2 58 688 (16.1) 56 961 (15.8) 0.1

aUnless otherwise specified, baseline characteristics were assessed on the birth date of the patient.

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.

gMetropolitan areas were defined as 6 metropolitan cities (Busan, Incheon, Gwangju, Daejeon, Daegu, and Ulsan), urban areas as cities, and rural areas as non-city areas. Missing data of observed data: control group = 3220, infantile colic group = 102; missing data of weighted data: control group = 3281, infantile group = 3157.

hObtained from the first National Health Screening Program of Infants and Children (NHSPIC) at 4-6 months of birth.

iObtained from the first NHSPIC at 4-6 months of birth. Missing data of all data: control group = 1506, infantile colic group = 33.

jIncome status was categorized into the quintile of insurance premium at birth. Missing data of all data: control group = 12 204, infantile colic group = 288; missing data of weighted data: control group = 12 338, infantile colic group = 12 109.

J Neurogastroenterol Motil 2022;28:618~629 https://doi.org/10.5056/jnm21181
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