Reversible and irreversible airflow obstruction as predictor of overall mortality in asthma and chronic obstructive pulmonary disease

The importance of reversible airflow obstruction to the prognosis of asthma and chronic obstructive pulmonary disease (COPD) is not clear. We tested t he hypothesis that reversibility to corticosteroid and bronchodilator is no t an independent predictor of prognosis, but merely reflects a component of the maximal attainable lung function, which is the best spirometric predic tor of survival. During a 6-yr period (1983-1988), 1,586 subjects with asth ma or COPD underwent standardized bronchodilator and corticosteroid reversi bility tests at a chest clinic in Copenhagen. The vital status was obtained by September 1997. The relationship between mortality and age, gender, smo king, FEV1, and reversibilities was examined by Cox proportional hazards an alyses. Of 1,586 subjects, 850 had died before September 1997. Age, smoking , and FEV1 were significant predictors of mortality. After controlling for baseline FEV1, bronchodilator and corticosteroid reversibility were signifi cantly associated with better survival. However, after controlling for best FEV1 all reversibilities became nonsignificant and nonpredictive. The comb ined use of corticosteroid and bronchodilator reversibility in survival ana lyses is a novel approach, and we have shown that both contribute to surviv al prediction to the extent that they modify FEV1. However, reversibility p er se does not influence survival in subjects with moderate to severe asthm a or COPD.