Familial associations of lung function between parents, offspring and siblings: a two-generation study of the ECRHS and RHINESSA cohorts

Background The familial aggregation of lung function is incompletely understood, as well as potential sex-specific patterns of associations within families. We aimed to investigate the associations of spirometry measures between parents and offspring and between siblings in two multicentre cohorts. Methods We studied n=1203 parent–offspring pairs and n=254 sibling pairs from the European Community Respiratory Health Survey (parents, mean age 35 years) and Respiratory Health in Northern Europe, Spain and Australia (offspring, mean age 31 years) cohorts. We used multilevel mixed-effect regression models to assess parent–offspring and between-siblings associations of forced expiratory volume in the first second (FEV 1 ) and forced vital capacity (FVC) (litres), adjusted for sex, age, height, smoking and body mass index, accounting for clustering within centres and families. Results FEV 1 and FVC were positively associated between parents and offspring (ß coef. (95% CI): FEV 1 0.19 (0.14 to 0.25), FVC 0.19 (0.14 to 0.25)) and between first and second sibling (ß coef. (95% CI): FEV 1 0.30 (0.17 to 0.43), FVC 0.20 (0.08 to 0.32)). The associations of FEV 1 and FVC between mothers and sons were significantly higher (p