Abstract
Objective. Pain is a patient-important outcome, but current reporting in randomized controlled trials and systematic reviews is often suboptimal, impeding clinical interpretation and decision making.
Methods. A working group at the 2014 Outcome Measures in Rheumatology (OMERACT 12) was convened to provide guidance for reporting treatment effects regarding pain for individual studies and systematic reviews.
Results For individual trials, authors should report, in addition to mean change, the proportion of patients achieving 1 or more thresholds of improvement from baseline pain (e.g., ≥ 20%, ≥ 30%, ≥ 50%), achievement of a desirable pain state (e.g., no worse than mild pain), and/or a combination of change and state. Effects on pain should be accompanied by other patient-important outcomes to facilitate interpretation. When pooling data for metaanalysis, authors should consider converting all continuous measures for pain to a 100 mm visual analog scale (VAS) for pain and use the established, minimally important difference (MID) of 10 mm, and the conventionally used, appreciably important differences of 20 mm, 30 mm, and 50 mm, to facilitate interpretation. Effects ≤ 0.5 units suggest a small or very small effect. To further increase interpretability, the pooled estimate on the VAS should also be transformed to a binary outcome and expressed as a relative risk and risk difference. This transformation can be achieved by calculating the probability of experiencing a treatment effect greater than the MID and the thresholds for appreciably important differences in pain reduction in the control and intervention groups.
Conclusion. Presentation of relative effects regarding pain will facilitate interpretation of treatment effects.
Footnotes
JAS is supported by grants from the US Agency for Health Quality and Research Center for Education and Research on Therapeutics U19 HS021110, National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS) P50 AR060772 and U34 AR062891, National Institute of Aging U01 AG018947, National Cancer Institute U10 CA149950, the resources and the use of facilities at the VA Medical Center at Birmingham, Alabama, USA, and research contract CE-1304-6631 from the Patient-Centered Outcomes Research Institute. MSA is the recipient of a K24 award from NIAMS (K24AR053593)
