Decline in lung function and mortality: implications for medical monitoring.
OBJECTIVE
To investigate the risk of death associated with selected cut-off points for rate of decline of forced expiratory volume in one second (FEV(1)).


METHODS
Mortality rates of a cohort of 1730 coal miners who had performed two pulmonary function tests 12.8 years apart were followed up for an additional 12 years. Based on previous studies, cut-off points for FEV(1) rate of decline (ml/year) were selected as 30, 60 and 90 ml/year. Cox proportional hazard regression was used to estimate multivariate risk ratio of death in each category.


RESULTS
The risk ratios (compared to "below 30 ml/year") were 1.39 (95% CI 0.99 to 1.97) in the "60 to less than 90 ml/year" category and 1.90 (95% CI 1.32 to 2.76) in the "90 ml/year and above" category. Rates of decline above 90 ml/year were consistently related to excess mortality. In non-smokers and those with neither restrictive nor obstructive patterns at the first survey, rates of decline above 60 ml/year were significantly associated with increased mortality.


CONCLUSIONS
Risk of death increases in individuals with rates of decline above about 60 ml/year and is statistically significant with declines of 90 ml/year or more. These results should be useful to healthcare providers in assessing lung function declines observed in individuals.
Sircar
Kanta
K
National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA. KSircar@cdc.gov
Hnizdo
Eva
E
Petsonk
Edward
E
Attfield
Michael
M
D000328:Adult; D003032:Coal Mining; D018450:Disease Progression; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008171:Lung Diseases / Q000401:mortality / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009784:Occupational Diseases / Q000401:mortality / Q000503:physiopathology*; D016016:Proportional Hazards Models; D018570:Risk Assessment / Q000379:methods