Introduction & Objective: Dysanapsis is the incongruent growth of lung parenchyma and the slower growth of the airways. It is associated with asthma in overweight children and is physiologically more common in females. Little is understood about it in adults. We sought to determine the relationship of dysanapsis in OSA patients with and without asthma.
Methods: Ethical approval was obtained for a retrospective review of electronic records of obstructive sleep apnoea patients followed up in sleep clinic for between 1st January 2020 and 31st January 2021. As only 16% of OSA clinic patients had asthma, we included the first 150 OSA with asthma and a further 150 without asthma. Dysanapsis was defined as FEV1/FVC <80% and FEV1 > 80% predicted.
Results: Of total 300, 32(with asthma) and 66(without asthma) were excluded due to co-existing other lung diseases. Of the remaining 202, 118 had OSA and asthma and 84 had OSA only. Obesity (BMI > 30kg/m2) was present in 102/118 (86%) and 72/84 (86%) respectively. Dysanapsis was present in 64/202 (32%) of which 47(73.4%) were males and 17(26.6%) were females, OR 1.5 (0.79-2.9 p=not significant). 42/64(65.6%) had asthma, OR 1.73(95% CI 0.92-3.27), p= 0.09.  Mean pre-treatment apnea-hypopnea index(AHI), available only for 184/202, was 28.3/hr in asthma and 38.6/hr in non-asthma (p= <0.001). When controlled for AHI, OR was 2.11(95% CI 1.02-4.36), p-value 0.045.
Conclusion: Dysanapsis is more common in males with OSA although this was non-significant. After controlling for AHI, significant association of dysanapsis and asthma was found in adult OSA patients. The significance of AHI remained unclear. This requires further research.