Defining Pain That Does Not Interfere With Activities Among Rheumatoid Arthritis (RA) Patients

OBJECTIVE: The objectives of this study were to: 1) characterize the distribution of non-interfering pain (defined as the pain intensity level at which individuals can function without interference) across different aspects of life among RA patients, and 2) identify clinical characteristics associated with differing levels of non-interfering pain. METHODS: RA patients in FORWARD-The National Databank for Rheumatic Diseases completed 8 items from the Patient-Reported Outcomes Measurement System (PROMIS) Pain Interference Item Bank that asked about interference with activities. If subjects reported pain interference, they were asked, "At what level would pain no longer interfere with this activity?" on a scale of 0 to 10. Subjects were also asked, "At what level of pain would you be able to do everything you want to do?" Multiple linear regression analyses examined associations between clinical characteristics and non-interfering pain. RESULTS: 3,949 RA patients completed the questionnaires. Pain interference was most common for daily activities and least common for ability to concentrate. The mean level at which pain no longer interfered with activities ranged from 2.7 +/- 2.1 for ability to fall/stay asleep to 3.1 +/- 2.0 for social activities. Overall, the mean threshold for non-interfering pain was 2.8 +/- 1.9. The mean level of pain at which patients could do everything they wanted to do was 2.3 +/- 1.9. More severe pain intensity was associated with higher non-interfering pain. CONCLUSION: The mean pain level that did not interfere with activities was 3. High pain intensity was associated with high self-reported non-interfering pain.