Table 2. Stratified IPTW-Adjusted Treatment Estimates for the Primary Outcome of Disability Days at 1 Year.
| Factors | No. of completers | Disability days at 1 y, mean (95% CI) | Difference (95% CI) | P value for interactiona | |
|---|---|---|---|---|---|
| Nonoperative management | Surgery | ||||
| Patient age, y | |||||
| ≤10 | 161 | 6.34 (4.9-8.19) | 10.33 (8.26-12.39) | −3.99 (−6.76 to −1.21) | .82 |
| >10 | 645 | 6.64 (5.42-7.86) | 11.00 (9.91-12.09) | −4.36 (−6.00 to −2.72) | |
| Annual household income, $ | |||||
| <50 000 | 207 | 7.10 (5.46-8.74) | 10.86 (9.09-12.64) | −3.77 (−6.18 to −1.35) | .99 |
| ≥50 000 | 504 | 5.84 (4.64-7.04) | 9.60 (8.52-10.68) | −3.76 (−5.37 to −2.15) | |
| Transfer status | |||||
| Not transferred | 462 | 6.81 (5.59-8.03) | 11.26 (9.88-12.63) | −4.44 (−6.28 to −2.60) | .81 |
| Transferred | 344 | 6.26 (4.48-8.03) | 10.34 (9.04-11.64) | −4.08 (−6.28 to −1.88) | |
| Sexb | |||||
| Male | 506 | 6.44 (5.23-7.65) | 10.64 (9.42-11.86) | −4.20 (−5.92 to −2.48) | .87 |
| Female | 300 | 6.81 (4.89-8.72) | 11.26 (9.67-12.86) | −4.46 (−6.95 to −1.96) | |
| Race and ethnicityb,c | |||||
| Non-Hispanic White | 484 | 6.37 (4.89-7.86) | 10.11 (9.04-11.17) | −3.73 (−5.56 to −1.91) | .34 |
| Other race/ethnicity | 322 | 6.87 (5.55-8.20) | 12.01 (10.20-13.81) | −5.14 (−7.38 to −2.89) | |
| Insurance statusb | |||||
| Private insurance | 585 | 6.08 (4.99-7.27) | 10.04 (9.06-11.02) | −3.96 (−5.50 to −2.42) | .38 |
| Medicaid | 198 | 7.89 (5.63-10.15) | 13.55 (10.92-16.18) | −5.66 (−9.13 to −2.20) | |
| Primary caregiver educationb | |||||
| Some college or less | 341 | 6.12 (4.65-7.60) | 11.12 (9.63-12.62) | −5.00 (−7.10 to −2.90) | .11 |
| At least college degree | 389 | 6.67 (5.10-8.24) | 9.32 (8.10-10.54) | −2.66 (−4.64 to −0.67) | |
| Primary language spoken at homeb | |||||
| English | 676 | 6.51 (5.37-7.65) | 10.20 (9.25-11.15) | −3.69 (−5.17 to −2.20) | .06 |
| Other | 92 | 6.01 (3.76-8.26) | 14.44 (10.28-18.59) | −8.42 (−13.15 to −3.70) | |
Interaction effects between treatment choice and the stratification factor were estimated through inverse probability of treatment weight (IPTW) linear regression models for disability days with differences between treatment groups estimated through marginal standardization. In all models, inference relied on robust sandwich-type standard errors to account for the estimated IPTWs.
Factor was added to the analysis post hoc.
Race and ethnicity were assessed because of evidence from the available literature suggesting an association with outcomes in pediatric patients treated for appendicitis. Related data were reported by caregivers using surveys with predefined categories listed in the table. Other includes Black, Hispanic, Asian, American Indian, Alaska Native, and biracial patients. For patients managed nonoperatively with complete follow-up, this included 163 non-Hispanic White patients, 15 non-Hispanic Black patients, 19 Hispanic patients, 83 patients who reported another race or ethnicity, and 4 patients who did not report race or ethnicity. For patients in the surgery group with complete follow-up, this included 321 non-Hispanic White patients, 12 non-Hispanic Black patients, 46 Hispanic patients, 137 patients who reported another race or ethnicity, and 6 patients who did not report race or ethnicity.