The relationship between airways responsiveness and chronic airflow limitation.

In 84 subjects with varying degrees of chronic airflow limitation (CAL), airways responsiveness (AR) measured by the response to an inhaled bronchodilator was negatively correlated with pulmonary function. Correlation coefficients were AR and FEV1, r = -0.39, p less than .001; AR and FEV1 percent predicted, r = -0.41, p less than .001; and between AR and FVC percent predicted, r = -0.28, p less than .006. This confirms the findings of others who used bronchoprovocation techniques to measure AR. Previously reported associations between AR and annual rate of change (ARC) of the FVC and FEV1 were reevaluated to determine if they are independent of any relationship between AR and baseline pulmonary function. Baseline FVC and FEV1 were not significantly correlated with ARC, while AR retained its significant association when evaluated by Pearson correlation coefficients and partial correlation coefficients adjusting for baseline FVC and FEV1, and when baseline values were included in liner regression models. Thus, AR in these subjects is a predictor of ARC of the FVC and FEV1 independent of baseline pulmonary function values.