PURPOSE:To develop an age-appropriate spirometric definition of COPD in older persons.
METHODS:We evaluated 2,480 community-living older persons, aged 65 to 80 years, from the Third National Health and Nutrition Examination Survey (NHANES III) who had no self-reported asthma. Participants completed spirometry and health questionnaires at baseline; all-cause mortality was determined from the National Death Index. We spirometrically defined COPD by first identifying the highest cut-point for the ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) that confers an increased risk of death. In participants with an FEV1/FVC below this threshold, we then identified the cut-points for the FEV1, expressed as a standardized residual percentile (SR-tile), that respectively confer an increased risk of death and an increased prevalence of respiratory symptoms. Regression models were adjusted for age, height, gender, ethnicity, smoking history, body mass index, chronic conditions, health status, and cognition.
RESULTS:The mean age was 71.7 years; 1,372 participants (55.4%) had a smoking history and 1,097 (44%) had respiratory symptoms. Over the course of 12 years, 868 participants (35.0%) died. Among participants with an FEV1/FVC < 0.70 and an FEV1 < 5th SR-tile, representing 7.7% of the cohort, the risk of death was doubled (adjusted hazard ratio=2.01; 95% confidence interval [CI]=1.60–2.54). Among participants with an FEV1/FVC < 0.70 and an FEV1 < 10th SR-tile, representing 13.4% of the cohort, the prevalence of respiratory symptoms was also elevated (adjusted odds ratio=2.44; 95% CI=1.79–3.33).
CONCLUSION:In a nationally representative sample of older persons, a spirometric definition of COPD based on FEV1/FVC < 0.70, with FEV1 cut-points at the 10th and 5th SR-tile, identifies individuals with an increased prevalence of respiratory symptoms and an increased risk of death, respectively.
CLINICAL IMPLICATIONS:This definition of COPD is clinically relevant and could lead to improvements in patient care and public health policy.
DISCLOSURE:Carlos Fragoso, No Financial Disclosure Information; No Product/Research Disclosure Information