Reduced lung function and cause-specific mortality: A population-based study of Norwegian men followed for 26 years

Background and aim: Reduced lung function is associated with increased mortality, but it is unclear how different spirometric patterns are related to specific deaths. Aim of this study was to investigate these associations in a large general population cohort. Methods: The study population consisted of 26,091 men aged 30-46 years from the Pneumoconiosis Survey of Western Norway conducted in 1988-1990 with follow-up on date and cause of death for 26 years. Cox proportional hazard models were used to estimate the association between baseline FEV1, FVC, obstructive (OSP) and restrictive spirometric pattern (RSP) (z-scores calculated according to GLI-2012 equations) and mortality (European 2012 shortlist classification (E-2012)), after adjustment for age, body mass index, smoking habits, and education. Results: In total, 2462 (9%) subjects died. A predominant reduction of FEV1 (and OSP) were associated with respiratory non-cancer (E-8) (HR for one unit FEV1 z-score decrease 2.29 (95% CI 1.90, 2.77) and lung cancer mortality (E-2.1.8) (1.27(1.12, 1.44)). A similar reduction of FEV1 and FVC (and RSP) were associated with diabetes (E-4.1) (FEV1 2.21(1.67, 2.92), FVC 2.41(1.75, 3.32)), cerebrovascular (E-7.3) (1.52(1.21, 1.91), 1.54 (1.19, 1.98)), ischemic heart disease (E-7.1) (1.22(1.10, 1.35), 1.21(1.08, 1.36)), neurological (E-6.3) (1.56 (1.21, 2.01), 1.61(1.22, 2.13)), suicide (E-17.2) (1.37(1.13, 1.65), 1.29(1.04, 1.59)) and hematological cancer mortality (E-2.1.19-21) (1.29(1.05, 1.58), (1.26(1.00, 1.58)). No association was found between reduced lung function and mortality due to accidents, alcohol abuse, digestive and genitourinary cancer. Conclusions: Spirometric obstruction was mainly related to pulmonary mortality. Spirometric restriction was mainly related to extra-pulmonary mortality.