Defining Pain That Does Not Interfere With Activities Among Rheumatoid Arthritis Patients.

Objective: The objectives of this study were to: 1) characterize the distribution of noninterfering pain (defined as the pain intensity level at which individuals can function without interference) across different aspects of life among patients with rheumatoid arthritis (RA), and 2) identify clinical characteristics associated with differing levels of noninterfering pain.

Methods: Patients with RA in FORWARD, The National Databank for Rheumatic Diseases completed 8 items from the Patient-Reported Outcomes Measurement Information 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 noninterfering pain.

Results: A total of 3,949 patients with RA completed the questionnaires. Pain interference was most common for daily activities and least common for ability to concentrate. The mean ± SD 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 ± SD threshold for noninterfering pain was 2.8 ± 1.9. The mean ± SD 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 noninterfering pain.

Conclusion: The mean pain level that did not interfere with activities was 3. High pain intensity was associated with high self-reported noninterfering pain.