Reporting of consent rates in critical care studies: room for improvement

Objectives: Reporting of consent rates in published articles is important to determine potential sources of bias and validity and generalizability of results. Our objective was to determine the percentage of critical care studies for which the consent rate was reported.

Study design and setting: We reviewed all articles published in eight medical journals in 2013. Studies meeting the following inclusion criteria were selected: (1) randomized controlled trial (RCT) or observational clinical study, (2) study population involving critically ill patients, and (3) part of the study occurring in an intensive care unit.

Results: A total of 1,871 articles were screened of which 156 were included. The consent rate was discernable in 30.8% of articles (48/156, 95% confidence interval: 24.1, 38.4) with a median consent rate of 86.9% (interquartile range, 71.6, 94.1). A statement on Research Ethics Board approval was included in 96.8% of studies. There was a significant difference in reporting of consent rates between RCTs and non-RCTs (58.70% vs. 19.09%, P < 0.0001).

Conclusion: Consent rates are reported in less than one-third of critical care studies. We encourage journals to require reporting of consent rates to improve interpretation, validity, and generalizability of critical care study results.