Aging-related considerations when evaluating the forced expiratory volume in 1 second (FEV1) over time

Abstract

Background: Forced expiratory volume in 1 second (FEV1) over time is commonly expressed in liters and percent predicted (%Pred), or alternatively in L/m3 and Z-scores-which approach is more clinically meaningful has not been evaluated. Because it uniquely accounts for the effect of aging on FEV1 and spirometric performance, we hypothesized that the Z-score approach is more clinically meaningful, based on associations between cardiopulmonary predictors and FEV1 over time. Methods: Using linear mixed-effects models and data from the Baltimore Longitudinal Study on Aging, including 501 white participants aged 40-95 who had completed at least three longitudinal spirometric assessments, we evaluated the associations between cardiopulmonary predictors (obesity, smoking status, hypertension, chronic bronchitis, diabetes mellitus, and myocardial infarction) and FEV1 over time, in liters, %Pred, L/m3, and Z-scores. Results: Mean baseline values for FEV1 were 3.240 L, 96.4%Pred, 0.621 L/m3, and -0.239 as a Z-score (40.6th percentile). The annual decline in FEV1 was 0.040 L, 0.234%Pred, 0.007 L/m3, and 0.008 Z-score units. Baseline age was associated with FEV1 over time in liters and L/m3 (p