Exploring the complexities of pain phenotypes: OMERACT 2023 chronic pain working group workshop.

OBJECTIVE: To educate and discuss pain mechanisms (nociceptive, neuropathic, nociplastic) illuminating its possible impact when measuring different outcomes, which may modify, confound and potentially bias the outcome measures applied across various aspects of Rheumatic Musculoskeletal Diseases (RMDs) clinical trials. METHODS: In the plenary presentations, PM lectured on different pain mechanisms and impact on disease activity assessment. Data from two data sets of RMDs patients, which assessed the prevalence and impact of nociplastic pain were presented and reviewed. Audience breakout group sessions and polling were conducted. RESULTS: Mixed pain etiologies may differentially influence disease activity assessment and therapeutic decision-making. Polling demonstrated a consensus on the need to assess different types of pain as a phenotype, as it constitutes an important contextual factor (a variable that is not an outcome of the trial, but needs to be recognized [and measured] to understand the study results), and to standardize across RMDs. CONCLUSION: There is need for a standardized pain measure that can differentiate underlying pain mechanisms.

Pain Measurement in Rheumatic and Musculoskeletal Diseases: Where To Go from Here? Report from a Special Interest Group at OMERACT 2018.

OBJECTIVE: Establishing a research agenda on standardizing pain measurement in clinical trials in rheumatic and musculoskeletal diseases (RMD). METHODS: Discussion during a meeting at the Outcome Measures in Rheumatology (OMERACT) 2018, prepared by a systematic review of existing core outcome sets and a patient online survey. RESULTS: Several key questions were debated: Is pain a symptom or a disease? Are pain core (sub)domains consistent across RMD? How to account for pain mechanistic descriptors (e.g., central sensitization) in pain measurement? CONCLUSION: Characterizing and assessing the spectrum of pain experience across RMD in a standardized fashion is the objective of the OMERACT Pain Working Group.