Pre- and post-bronchodilator lung function as predictors of mortality in the Lung Health StudyReport as inadecuate




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Respiratory Research

, 12:136

First Online: 01 December 2011Received: 14 July 2011Accepted: 12 October 2011

Abstract

BackgroundChronic obstructive pulmonary disease COPD is supposed to be classified on the basis of post-bronchodilator lung function. Most longitudinal studies of COPD, though, do not have post-bronchodilator lung function available. We used pre-and post bronchodilator lung function data from the Lung Health Study to determine whether these measures differ in their ability to predict mortality.

MethodsWe limited our analysis to subjects who were of black or white race, on whom we had complete data, and who participated at either the 1 year or the 5 year follow-up visit. We classified subjects based on their baseline lung function, according to COPD Classification criteria using both pre- and post-bronchodilator lung function. We conducted a survival analysis and logistic regression predicting death and controlling for age, sex, race, treatment group, smoking status, and measures of lung function either pre- or post-bronchodilator. We calculated hazard ratios HR with 95% confidence intervals CI and also calculated area under the curve for the logistic regression models.

ResultsBy year 15 of the study, 721 of the original 5,887 study subjects had died. In the year 1 sample survival models, a higher FEV1 % predicted lower mortality in both the pre-bronchodilator HR 0.87, 95% CI 0.81, 0.94 per 10% increase and post-bronchodilator HR 0.84, 95% CI 0.77, 0.90 models. The area under the curve for the respective models was 69.2% and 69.4%. Similarly, using categories, when compared to people with -normal- lung function, subjects with Stage 3 or 4 disease had similar mortality in both the pre- HR 1.51, 95% CI 0.75, 3.03 and post-bronchodilator HR 1.45, 95% CI 0.41, 5.15 models. In the year 5 sample, when a larger proportion of subjects had Stage 3 or 4 disease 6.4% in the pre-bronchodilator group, mortality was significantly increased in both the pre- HR 2.68, 95% CI 1.51, 4.75 and post-bronchodilator HR 2.46, 95% CI 1.63, 3.73 models.

ConclusionsBoth pre- and post-bronchodilator lung function predicted mortality in this analysis with a similar degree of accuracy. Post-bronchodilator lung function may not be needed in population studies that predict long-term outcomes.

KeywordsCOPD mortality epidemiology bronchodilator responsiveness  Download fulltext PDF



Author: David M Mannino - Enrique Diaz-Guzman - Sonia Buist

Source: https://link.springer.com/







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