Increased risk of appendectomy in patients with asthma: A nested case-control study using a national sample cohort

The study aimed to expand previous data regarding an association between asthma and appendectomy in children compared with the population of all ages. The Korean Health Insurance Review and Assessment Service—National Sample Cohort from 2002 through 2013 was used. In all, 22,030 participants who underwent appendectomy were matched for age, sex, income, region of residence, hypertension, diabetes, and dyslipidemia with 88,120 participants who were included as a control group. In both the appendectomy and control groups, previous history of asthma was investigated. Appendectomy for appendicitis was identified based on a surgical code (International Classification of Disease-10 [ICD-10]: K35). Asthma was classified using an ICD-10 code (J45 and J46) and medication history. The crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of asthma for appendectomy were analyzed using conditional logistic regression analysis. Subgroup analyses were conducted according to age and sex. Approximately 15.2% (3358/22,030) of individuals in the appendectomy group and 13.3% (11,749/88,120) of those in the control group had asthma (P < .001). The appendectomy group demonstrated a higher adjusted odds of asthma than the control group (adjusted OR 1.18, 95% CI 1.13–1.23, P < .001). This result was consistent in the subgroups divided according to age and sex. The odds for asthma were higher in the appendectomy group than in the control group.