Pain Predicts Function One Year Later: A Comparison across Pain Measures in a Rheumatoid Arthritis Sample

Background . Guidance is limited on best measures and time periods to reference when measuring pain in order to predict future function. Objective . To examine how different measures of pain predict functional limitations a year later in a sample of rheumatoid arthritis patients. Methods . Logistic regression analyses were conducted using baseline and one-year data ( n = 262). Pain intensity in the last 24 hours was measured on a 0–10 numerical rating scale and in the last month using an item from the Arthritis Impact Measurement Scale 2 (AIMS2). AIMS2 also provided frequency of severe pain, pain composite scores, and patient-reported limitations. Physician-rated function was also examined. Results . Composite AIMS2 pain scale performed best, predicting every functional outcome with the greatest magnitude, a one-point increase in pain score predicting 21% increased odds of limitations (combined patient and physician report). However, its constituent item—frequency of severe pain in the last month—performed nearly as well (19% increased odds). Pain intensity measures in last month and last 24 hours yielded inconsistent findings. Conclusion . Although all measures of pain predicted some functional limitations, predictive consistency varied by measure. Frequency of severe pain in the last month provided a good balance of brevity and predictive power.