Lifetime spirometric patterns of obstruction and restriction: risk factors and outcomes

Rationale & Aim: There is increasing interest in lung function trajectories but the focus to date has been on obstructive patterns without taking restrictive patterns into account. We investigated these patterns concurrently over the lifespan Methods: Using group-based trajectory modelling of spirometry collected from 7 to 53 years in the Tasmanian Longitudinal Health Study (n=2,438), 6 FEV1/FVC and 5 FVC trajectories were identified. Three FEV1/FVC trajectories were collectively recognised as ‘low’ and one FVC trajectory as ‘low’. Based on whether trajectories of FEV1/FVC and FVC were ‘low’, 4 patterns of lifetime spirometry trajectories were identified. Risk factors and consequences of these patterns were investigated Results: The prevalence of the lifetime patterns were: low FEV1/FVC-only 25.8%; low FVC-only 10.4%; both low FEV1/FVC and low FVC, labelled as ‘mixed’ 3.5%, and neither low (60.2%). Those with the mixed pattern had the highest prevalence of COPD at age 53 years (36.9%) followed by the low FEV1/FVC-only pattern (21.6%). Those with the mixed pattern had the highest prevalence of parental asthma, childhood respiratory illnesses, adult asthma and mental health disorders. Those with the low FVC-only pattern had low total lung capacity and residual volume and had the highest prevalence of childhood underweight, adult obesity, diabetes and cardiovascular conditions Conclusion: We identified physiological patterns of lifetime spirometric airway obstruction, restriction and both/mixed. Mixed and obstructive patterns identify those who may benefit from early interventions. The restrictive pattern identifies those at higher risk of multi-morbidity by middle-age