Evaluation of a novel method to assess corticosteroid responsiveness in chronic obstructive pulmonary disease

BACKGROUND: Some patients with chronic obstructive pulmonary disease (COPD) may benefit from oral steroid therapy. These steroid-responsive patients are diagnosed based on laboratory spirometry. We hypothesize that daily, home-based spirometry is a better tool. METHODS: Thirty patients with COPD underwent a single-blinded study, with a crossover design. They received 2 weeks of placebo followed by 2 weeks of prednisone therapy (40 mg/day). Laboratory spirometry was done at the beginning and end of the study and daily home-based spirometry was done twice a day. RESULTS: Analysis of variance model was used. The variability of the median day-to-day forced expiratory volume in 1 s (FEV₁) was 72.5 mL (25th percentile of 40 mL and 75th percentile of 130 mL). The daily FEV₁ variation was 70 mL (25th percentile of 50 mL and 75th percentile of 100 mL). The overall laboratory FEV₁ variability was larger after the steroid course (P < 0.001), but not clinically significant. The variability was not significant postplacebo treatment compared with the baseline values. For home-based spirometry, steroid treatment was not significantly different. The majority (97%) completed more than 80% of the measurements. Ninety percent of the performed tests were considered acceptable. Only 53% of the tests were considered accurate. Overall both laboratory and home-based measurements did not show significant association between airway responsiveness and dyspnea or exercise capacity. CONCLUSION: Twice-daily home measurements of FEV₁ might be better than the conventional approach to identify steroid responsive COPD patients. However, this finding was only statistically but not clinically significant. Therefore, we would not recommend this approach to identify COPD patients with steroid responsiveness.