Background Little is known about the diagnostic patterns of obstructive sleep apnoea (OSA) in children. A study was undertaken to evaluate morbidity and mortality in childhood OSA.

Methods 2998 patients aged 0–19 years with a diagnosis of OSA were identified from the Danish National Patient Registry. For each patient we randomly selected four citizens matched for age, sex and socioeconomic status, thus providing 11 974 controls.

Results Patients with OSA had greater morbidity at least 3 years before their diagnosis. The most common contacts with the health system arose from infections (OR 1.19, 95% CI 1.01 to 1.40); endocrine, nutritional and metabolic diseases (OR 1.30, 95% CI 0.94 to 1.80); nervous conditions (OR 2.12, 95% CI 1.65 to 2.73); eye conditions (OR 1.43, 95% CI 1.07 to 1.90); ear, nose and throat (ENT) diseases (OR 1.61, 95% CI 1.33 to 1.94); respiratory system diseases (OR 1.78, 95% CI 1.60 to 1.98); gastrointestinal diseases (OR 1.34, 95% CI 1.09 to 1.66); skin conditions (OR 1.32, 95% CI 1.02 to 1.71); congenital malformations (OR 1.56, 95% CI 1.31 to 1.85); abnormal clinical or laboratory findings (OR 1.21, 95% CI 1.06 to 1.39); and other factors influencing health status (OR 1.29, 95% CI 1.16 to 1.43). After diagnosis, OSA was associated with incidences of endocrine, nutritional and metabolic diseases (OR 1.78, 95% CI 1.29 to 2.45), nervous conditions (OR 3.16, 95% CI 2.58 to 3.89), ENT diseases (OR 1.45, 95% CI 1.14 to 1.84), respiratory system diseases (OR 1.94, 95% CI 1.70 to 2.22), skin conditions (OR 1.42, 95% CI 1.06 to 1.89), musculoskeletal diseases (OR 1.29, 95% CI 1.01 to 1.64), congenital malformations (OR 1.83, 95% CI 1.51 to 2.22), abnormal clinical or laboratory findings (OR 1.16, 95% CI 1.06 to 1.27) and other factors influencing health status (OR 1.35, 95% CI 1.20 to 1.51). The 5-year death rate was 70 per 10 000 for patients and 11 per 10 000 for controls. The HR for cases compared with controls was 6.58 (95% CI 3.39 to 12.79; p<0.001).

Conclusions Children with OSA have significant morbidities several years before and after their diagnosis.