Aim: To investigate the risk of death associated with selected cut-off points for rate of decline of forced expiratory volume in one second (FEV1).
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 FEV1 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.
- ATS, American Thoracic Society
- BMI, body mass index
- FEV1, forced expiratory volume in one second
- ICD-9, International Classification of Diseases Ninth Revision
- NSCWP, National Study of Coal Workers’ Pneumoconiosis
- PFT, pulmonary function test
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Published Online First 1 March 2007
Funding: National Institute for Occupational Safety and Health.
Competing interests: None.
The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health.