Airflow reversibility and long-term outcomes in patients with COPD without comorbidities

Abstract

Background: The forced expiratory volume at first second (FEV(1)) during spirometry reflects the severity of chronic obstructive pulmonary disease (COPD) and is known to be an important prognostic factor. It is uncertain whether the response to short-acting bronchodilators may predict long-term outcomes such as hospitalizations and mortality.

Methods: We retrospectively studied a total of 1203 consecutive COPD patients without significant comorbidities during a mean (±SD) of 69 ± 39 months of follow-up. At baseline the subjects were classified as those with positive or negative bronchodilator test (BDT) and also in quartiles of absolute bronchodilator response to 400 μg of salbutamol. Hospital visits and mortality were the end points.

Results: A positive bronchodilator test was observed in 332 (27.6%) of the patients. There were 73 (21.9%) deaths in patients with a positive BDT versus 253 (28.7%) in those with a negative BDT (p = 0.04). In adjusted Cox regression analysis a positive BDT was significantly associated with a prolonged time to first hospitalization. After stratifying the population by quartiles of response to BDT, a dose-response relationship was observed with the best outcomes in the quartile with highest level of airflow reversibility, even after controlling for age, sex, BMI, smoking status and baseline postbronchodilator FEV(1).

Conclusions: In a large population of well characterized COPD patients without significant comorbidities, those demonstrating higher levels of reversibility at baseline presented better long-term outcomes even after controlling for other known prognostic factors.

Keywords: Bronchodilator test; COPD; Hospitalization; Mortality; Reversibility.