This study examined within-day osteoarthritis (OA)-related pain patterns and associated patient characteristics.
Participants with physician diagnoses and self-reported symptoms of hand (N=40), hip (N=32), and knee (N=85) OA recorded pain using a handheld computer on one weekday and one weekend day, with ratings beginning immediately after waking, then approximately every 2h following. Pain was rated on a sliding visual analog scale with hidden coding of 1-100. Multivariable linear mixed models examined associations of patient demographic characteristics, enrollment site (Durham VA Medical Center vs Duke University Medical Center), joint site, body mass index, and pain medication use with within-day pain range (maximum minus minimum pain rating) and area under the curve (AUC) of pain ratings, which incorporates the magnitude of all pain measurements.
Pain patterns differed substantially across individuals. The sample means of the average, maximum, and minimum weekday pain scores were 35.3, 54.4, and 17.9, respectively. The mean pain range was 36.4, and the mean pain AUC was 564.3 (possible range: 16-1600). Pain scores were similar on weekends. In multivariable mixed models, both knee and hip OA were associated with a greater within-day pain range than hand OA. Only VA enrollment site was associated with a significantly greater pain AUC.
There is substantial within-day range in OA-related pain. Both pain range and overall within-day magnitude vary according to patient characteristics. Patients' records of within-day pain patterns could be used in clinical encounters to tailor recommendations for the timing of medication use and behavioral strategies.