Subjective and objective outcomes in randomized clinical trials: definitions differed in methods publications and were often absent from trial reports

The terms “subjective” and “objective” are ambiguous when used to describe outcomes in randomized clinical trials. We suggest that the terms should be defined explicitly when used in connection with the assessment of risk of bias in a clinical trial, in metaepidemiological research, and generally in the reporting of clinical trials. We also suggest that adding an explicit clarification of the terms in future versions of the Cochrane Handbook might further strengthen its important role in guiding review authors.