Response to corticosteroids in chronic airflow obstruction: relationship to emphysema and airways collapse.

We have studied the relationship between emphysema and airways collapse, and response to corticosteroids in patients with chronic airflow obstruction. One hundred and seven patients completed a placebo-controlled trial comparing 2 wks treatment with oral prednisolone 40 mg.day-1 to inhaled beclomethasone dipropionate 500 micrograms t.d.s. Response to corticosteroids was defined on the basis of changes in forced expiratory volume in one second (FEV1), and/or forced vital capacity (FVC), and/or mean peak expiratory flow (PEF) after treatment. Patients were categorized as those with physiologically defined emphysema (carbon monoxide transfer coefficient (KCO) less than 70% predicted and total lung capacity greater than 120% predicted), and those with pressure dependent airways collapse on the flow-volume loop (ratio of inspiratory to expiratory flow at 50% vital capacity [I:E50] greater than 10). The response to placebo showed a significant order effect, probably due to a carry-over effect of active treatment of at least 3 wks. Hence, the efficacy of active treatment over placebo in the subgroups defined was assessed by analysis of data generated from the first treatment phase of the trial. The presence or absence of physiologically defined emphysema did not affect the response to oral prednisolone. Inhaled beclomethasone dipropionate, however, was less effective in the emphysema group. Pressure dependent airways collapse did not affect the response to either prednisolone or beclomethasone. However, when data from all three treatment phases were analysed there was no significant difference in the response to either drug in any of the subgroups defined.(ABSTRACT TRUNCATED AT 250 WORDS)