Asthma in Children With Congenital Lung Malformations: A Population‐Based Case‐Control Study

BACKGROUND: Congenital lung malformations (CLM) are developmental anomalies that may predispose to respiratory morbidity. Their association with asthma remains unclear, largely due to small series and the lack of population-based controls. OBJECTIVE: To evaluate asthma prevalence and related outcomes in children with CLM compared to population controls. METHODS: We conducted a population-based case-control study linking CLM patients from a surgical registry to provincial health data. Each CLM patient was linked to up to ten date-of-birth-matched controls. Asthma was defined by ICD-9/10 codes from age ≥5 years. Outcomes included asthma prevalence, time to first diagnosis, recurrent medical encounters, and pharmacotherapy patterns. Analyses yielded risk ratios (RR), adjusted hazard ratios (aHR), and adjusted incidence rate ratios (aIRR). RESULTS: Forty-nine CLM cases and 486 controls were included. Asthma was diagnosed in 19 (38.8%) CLM cases versus 76 (15.6%) controls (RR = 2.48, 95% CI [1.65-3.73]; p < 0.001). The RR did not differ between surgically and conservatively managed CLM cases (RR = 2.87, 95% CI [0.45-18.32]; p = 0.234). CLM cases had a threefold higher hazard of asthma (aHR = 3.24, 95% CI [1.84-5.71]; p < 0.001). Female cases were particularly affected (aHR = 3.92, 95% CI [1.98-7.74]; p < 0.001), with no difference observed in males (aHR = 1.98, 95% CI [0.90-4.37]; p = 0.092). Annually, CLM patients accumulated 71% more asthma-related encounters (aIRR = 1.71, 95% CI [1.28-2.25]; p < 0.001). CONCLUSIONS: Children with CLM are at increased risk of asthma, especially females, with earlier onset and more frequent encounters. These findings highlight the need for long-term respiratory follow-up and objective validation of asthma diagnoses in this population.