Argument for changing criteria for bronchodilator responsiveness

Background: Extensively used current guidelines of the American Thoracic Society/European Respiratory Society (ATS/ERS) define a positive aerosolized bronchodilator (BD) response as: "... an increase in FEV1 and/or FVC >= 12% of control and >= 200 mL." We hypothesized that BD responsiveness was better assessed using a statistical approach, [inked to each individual's spirometric measurements, rather than the variability of others. Design: We retrospectively analyzed 1 -year's pre- and post-BD spirometric tests from our hospital's clinical laboratory. Using measurements of forced expiratory volume in 1 -s (FEV1), forced expiratory volume in 3-s (FEV3), and forced vital capacity (FVC) from each of three satisfactory forced pre-BD and three satisfactory forced post-BD spirometric maneuvers, we classified each of 313 consecutive patient studies as responders or non-responders in two ways. First, we used ATS/ERS guideline criteria based on population variability. Second, we used unpaired, single-tailed t-tests at P < 0.05 for FEV1, FEV3, and FVC, considering the variability of and difference between each individual's pre- and post-BD maneuvers. Results: 135 studies were both ATS/ERS and t-test non-responders, three were ATS/ERS responders and t-test non-responders, 86 were ATS/ERS and t-test responders, and 89 were ATS/ERS non-responders and t-test responders. The latter 89 included many patients with either low baseline FEV1 (<1.50 L) who could not reach the 200 mL increase criterion or high baseline FEV, (>3.00 L) who could not reach the 12% increase criterion. Conclusions: We believe individual t-tests may categorize patient's BD responsiveness better than ATS/ERS guideline criteria which are based on population responses and require both fixed volume and percentage changes. Its usefulness by others remains to be shown. (C) 2008 Elsevier Ltd. All rights reserved.