Risk of bias assessment of randomised controlled trials referenced in the 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care: a cross-sectional review

OBJECTIVES: To identify the risk of bias of randomised controlled trials (RCTs) referenced in the 2015 American Heart Association (AHA) guidelines update for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC). DESIGN: A cross-sectional review. SETTING: All RCTs cited as references in the 2015 AHA guidelines update for CPR and ECC were extracted. After excluding non-human trials, studies that analysed existing RCTs, and RCTs published in a letter format, two reviewers assessed the risk of bias among RCTs included in this study. OUTCOME MEASURES: The Cochrane Collaboration’s tool for assessing the risk of bias in six domains (random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data and selective reporting) was used. RESULTS: Two hundred seventy-three RCTs were selected for the analyses. Of these RCTs, 78.8% had a high risk of bias for blinding of participants and personnel, mostly (87.7%) non-drug trials. In drug trials, the proportion of trials with a low risk of bias for blinding of participants and personnel was 73.0%. The proportion of RCTs with an unclear risk of bias were higher for random sequence generation (38.5%) and allocation concealment (34.1%) than in other domains. Unclear risk of bias proportions was 65.4% for random sequence generation and 57.7% for allocation concealment before the introduction of Consolidated Standards of Reporting Trials (CONSORT) but decreased to 31.3% and 32.2% after the 2010 CONSORT update, respectively. CONCLUSIONS: The proportion of RCTs with an unclear risk of bias was still high for random sequence generation and allocation concealment in the 2015 AHA guidelines for CPR and ECC. The risk of bias should be considered when interpreting and applying the CPR guidelines. Authors should plan and report their research using CONSORT guidelines and the Cochrane Collaboration’s tool to reduce the risk of bias.