Prognostic value of FEV1/FEV6 in elderly people

Abstract

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 7·00 and 2·46 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: 2·84, 95%CI: 2·12-3·84). 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): 1·87, 95%CI: 1·35-2·58] as well as in subjects with FEV1/FVC<LLN (HR: 2·01, 95%CI: 1·51-2·90) and FEV1<LLN (HR: 2·17, 95%CI: 1·32-3·57). 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.