Current approaches to handling rescue medication in asthma and eczema randomized controlled trials are inadequate: a systematic review

OBJECTIVES: The objective of this study was to examine how rescue medication is defined, reported, and accounted for in randomized controlled trials (RCTs) in eczema and asthma populations. STUDY DESIGN AND SETTING: This is a systematic review of phase II/III RCTs evaluating monoclonal antibodies for treating chronic eczema or asthma. A search of EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials was conducted to identify eligible RCTs. RESULTS: Sixty published RCTs were identified, of which 60 (100%) allowed use of rescue medication but only 28 (47%) reported its use. Twenty-seven (45%) articles summarized rescue use by arm, with an average of 25% (95% CI (17%, 36%)) greater use in the placebo arm. Nine (15%) trials undertook an analysis that adjusted the primary treatment effect estimate for rescue medication use, but 8 of these used a suboptimal approach using single imputation, including 4 which used “last observation carried forward” after setting postrescue data to missing. CONCLUSION: Rescue medication use in eczema and asthma trials evaluating monoclonal antibodies is often permitted, but not routinely reported. There is evidence of imbalance in rescue use between arms, but few articles attempted to estimate a rescue-adjusted treatment effect. In trials that did, the methods used were suboptimal which could introduce bias.