Prognostic value of FEV1/FEV6 in elderly people

Background: The ratio of forced expiratory volume in 1 s and forced expiratory volume in 6 s (FEV1/FEV6) has been proposed as an alternative for FEV1/forced vital capacity (FVC) to diagnose obstructive diseases with less effort during spirometry; however, its prognostic value is unknown. We evaluated whether FEV1/FEV6 is a significant predictor of mortality in elderly subjects and compared its prognostic value with that of FEV1/FVC and FEV1. Methods: One thousand nine hundred and seventy-one subjects, aged > 65 years, participated in the population-based SA.R.A. study. During the baseline exam, a multidimensional assessment included spirometry. Vital status was determined during 6 years of follow-up. Association of all-cause, cardio-pulmonary (CP) and non-CP mortality with a low FEV1/FEV6, FEV1/FVC and FEV1 was evaluated. Results: Among subjects with both survival data and acceptable spirometry including FEV6, all-cause unadjusted mortality rates were 7 center dot 00 and 2 center dot 46 per 100 person-years in subjects with FEV1/FEV6 less than and greater than or equal to lower limit of normal (LLN), respectively (mortality rate ratio: 2 center dot 84, 95%CI: 2 center dot 12-3 center dot 84). After adjustment for age, gender, FVC, smoke exposure and main comorbidities, the risk of all-cause mortality remained significantly increased in subjects with FEV1/FEV6 < LLN [hazard ratio (HR): 1 center dot 87, 95%CI: 1 center dot 35-2 center dot 58] as well as in subjects with FEV1/FVC < LLN (HR: 2 center dot 01, 95%CI: 1 center dot 51-2 center dot 90) and FEV1 < LLN (HR: 2 center dot 17, 95%CI: 1 center dot 32-3 center dot 57). Similar results were found for CP mortality, but not for non-CP mortality. Conclusions: A low FEV1/FEV6 is a significant predictor of mortality in older individuals. Its prognostic value is comparable to that of a low FEV1/FVC and FEV1.