Patient-reported outcomes in meta-analyses - Part 1: assessing risk of bias and combining outcomes

Systematic reviews and meta-analyses of randomized trials that include patient-reported outcomes (PROs) often provide crucial information for patients and clinicians facing challenging health care decisions. Based on emerging methods, guidance on combining PROs in meta-analysis is likely to enhance their usefulness. The objectives of this paper are: i) to describe PROs and why they are important for health care decision-making, ii) illustrate the key risk of bias issues that systematic reviewers should consider and, iii) address outcome characteristics of PROs and provide guidance for combining outcomes. We suggest a step-by-step approach to addressing issues of PROs in meta-analyses. Systematic reviewers should begin by asking themselves if trials have addressed all the important effects of treatment on patients' quality of life. If the trials have addressed PROs, have investigators chosen the appropriate instruments? In particular, does evidence suggest the PROs used are valid and responsive, and is the review free of outcome reporting bias? Systematic reviewers must then decide how to categorize PROs and when to pool results.