Table 3.
Weighted risk ratios of clinical conditions in the exposed group relative to the reference group.
| Observed Data (N = 206,248) | Weighted Data (N = 199,952) c | Weighted IRR | |||
|---|---|---|---|---|---|
| Outcomes, N(%) a, b | Non-Exposed (N = 165,925) |
Exposed (N = 40,323) |
Non-Exposed (N = 160,897) |
Exposed (N = 39,055) |
(95% CI), % d |
| Pneumonia | 21,628 (13.03) | 5274 (13.08) | 21,048 (13.08) | 5065 (12.97) | 0.99 (0.96 to 1.02) |
| Asthma | 1460 (0.88) | 381 (0.94) | 1416 (0.88) | 366 (0.94) | 1.06 (0.95 to 1.19) |
| URTI | 8783 (5.29) | 2226 (5.51) | 8583 (5.33) | 2125 (5.44) | 1.02 (0.97 to 1.07) |
| Acute gastroenteritis | 10,995 (6.63) | 2768 (6.86) | 10,688 (6.64) | 2672 (6.84) | 1.03 (0.99 to 1.07) |
| Acute otitis media | 1314 (0.79) | 300 (0.74) | 1272 (0.79) | 293 (0.75) | 0.95 (0.84 to 1.08) |
| Tooth decay | 2181 (1.31) | 490 (1.22) | 2111 (1.31) | 474 (1.21) | 0.93 (0.84 to 1.03) |
| ADHD e | 648 (0.39) | 142 (0.35) | 626 (0.39) | 137 (0.35) | 0.90 (0.75 to 1.08) |
| Autism spectrum disorder | 276 (0.17) | 68 (0.17) | 258 (0.16) | 62 (0.16) | 1.00 (0.76 to 1.32) |
| Epilepsy | 579 (0.35) | 130 (0.32) | 562 (0.35) | 126 (0.32) | 0.92 (0.76 to 1.12) |
| Malignancy | 183 (0.11) | 49 (0.12) | 176 (0.11) | 47 (0.12) | 1.10 (0.79 to 1.51) |
Abbreviations: ADHD, attention-deficit/hyperactivity disorder; IRR, incidence risk ratio; IPTW, inverse probability of treatment weighting; NHIS, National Health Insurance Service; URTI, upper respiratory tract infection. a Results are reported as n (%) unless otherwise indicated. b Diseases are listed in Supplementary Table S1. To enhance outcome specificity, only the code entered in the main diagnosis field of the database was utilized, as it had the most significant influence on a patient’s hospital stay and resource utilization. Subsequent clinical conditions recorded after 24 months were investigated unless otherwise stated. c IPTW on the propensity score was used to balance the groups for baseline health data. Seventy covariates were weighted (Table 1 and Supplementary Tables S3 and S4). Individuals in the reference group were weighted using stabilized weights to produce a sample with the same distribution of covariates as the exposed group. d Calculated using modified Poisson regression. e Diagnosis after 48 months of age from the NHIS database.