Effectiveness of pulmonary rehabilitation for patients with asthma: study protocol of a randomized controlled trial (EPRA)

Background: Asthma patients are enrolled in multimodal pulmonary rehabilitation (PR) programs. However, available data for the effectiveness of PR in asthma are sparse. Therefore, the primary aim of this randomized control trial (RCT) is to evaluate short-term (end of rehabilitation) and intermediate-term effectiveness (3 months after rehabilitation) of PR for patients with asthma regarding asthma control (primary outcome) and other outcomes. Secondly, moderator effects of gender, age, baseline asthma control, quality of life, and anxiety will be examined. Thirdly, a longitudinal follow-up study will explore the course of the outcomes over one year and the annual costs. Methods: The EPRA study is a single-center randomized controlled waiting-list trial in the Bad Reichenhall Clinic. Inclusion criteria include a referral diagnosis for uncontrolled asthma, no cognitive impairment and no very severe co-morbidities that indicate significantly greater illness morbidity than asthma alone. In the intervention group (IG), participants will start PR within 4 weeks after randomization; participants of the control group (CG) will start PR 20 weeks after randomization. Data will be assessed at randomization (T0), after 4 weeks (T1; IG: begin of PR), 7 weeks (T2; IG: end of PR), and 20 weeks (T3, CG: begin of PR). The primary outcome is asthma control at T2/T3. Secondary outcomes are health-related quality of life, functional exercise capacity, dyspnea, anxiety, depression, subjective selfmanagement skills, illness perceptions, sick leave and subjective work ability. Outcomes will be analyzed with analysis of covariance, including baseline values of the respective outcomes as covariates. Healthcare costs will be analyzed with a gamma model with a log-link. A longitudinal follow-up study will generate additional data at 3/6/9/12 months after PR for both IG and CG. Latent change models will be used to analyze the course of the primary and secondary outcomes. Annual cost differences before and after rehabilitation will be compared by paired t-test. Discussion: This RCT will determine the effectiveness of a complex inpatient PR for asthma patients concerning asthma control. Furthermore, important medical and economic information regarding the effectiveness of PR as part of the long-term management of patients with uncontrolled asthma will be generated.