The Longitudinal Examination of Arthritis Pain (LEAP) study: relationships between weekly fluctuations in patient-rated joint pain and other health outcomes

OBJECTIVE: To examine relationships between weekly fluctuations in self-rated joint pain and other health outcomes among adults with osteoarthritis (OA). METHODS: In this observational study, 287 adults (aged > or = 50 yrs) with hip or knee OA were recruited from 16 medical practices across the United States. Patients were telephoned weekly for 12 weeks to assess pain/stiffness, daily activities/function, productivity, emotional well-being, quality of life, and healthcare utilization. Associations between changes in joint pain levels and other health outcomes were evaluated using a generalized estimating equation model. RESULTS: The mean (SD) pain score at Week 1 was 4.2 (2.1) on the Western Ontario and McMaster Universities OA index (WOMAC) pain subscale (0 = no pain, 10 = extreme pain); during the study, 49% of patients reported a between-week fluctuation of > or = 2 points. A 2-point decrease in WOMAC pain subscale score was associated with a 22% decrease in number of days of limited activity/week (beta = -0.107; 95% confidence interval -0.163, -0.051); a 48% decrease in number of days of missed work/week (beta = -0.217; 95% CI -0.395, -0.039); a 14% decrease in number of nights with pain-related sleep interference/week (beta = -0.068; 95% CI -0.109, -0.027). Patients were 1.6 times more likely to contact a healthcare provider when their pain changed from "acceptable" to "unacceptable." CONCLUSION:Weekly fluctuations in pain levels and other health outcomes were identified among adults with OA. Decreases in patient-reported pain were associated with improvements in daily activities/functioning and decreases in work absenteeism, sleep interference, and healthcare resource use.