Core Outcome Measures for Chronic Musculoskeletal Pain Research: Recommendations from a Veterans Health Administration Work Group

Objective: Chronic musculoskeletal pain (CMSP) disorders are among the most prevalent and disabling conditions worldwide. It would be advantageous to have common outcome measures when comparing results across different CMSP research studies. Methods: The Veterans Health Administration appointed a work group to recommend core outcome measures for assessing pain intensity and interference as well as important secondary domains in clinical research. The work group used three streams of data to inform their recommendations: 1) literature synthesis augmented by three recently completed trials; 2) review and comparison of measures recommended by other expert groups; 3) two Delphi surveys of work group members. Results: The single-item numerical rating scale and seven-item Brief Pain Inventory interference scale emerged as the recommended measures for assessing pain intensity and interference, respectively. The secondary domains ranked most important included physical functioning and depression, followed by sleep, anxiety, and patient-reported global impression of change (PGIC). For these domains, the work group recommended the Patient-Reported Outcome Information System four-item physical function and sleep scales, the Patient Health Questionnaire two-item depression scale, the Generalized Anxiety Disorder two-item anxiety scale, and the single-item PGIC. Finally, a single-item National Health Interview Survey item was favored for defining chronic pain. Conclusions: Two scales comprising eight items are recommended as core outcome measures for pain intensity and interference in all studies of chronic musculoskeletal pain, and brief scales comprising 13 additional items can be added when possible to assess important secondary domains.