Rhythmic variations in pain, stiffness, and manual dexterity in hand osteoarthritis.

OBJECTIVE To explore circadian variation in pain, stiffness, and manual dexterity in patients with hand osteoarthritis (OA). METHODS Twenty one patients with hand OA, as defined by ACR criteria (17 women, four men, mean age 62.2 years, range 52-74 years) self rated pain and stiffness on separate 10 cm horizontal visual analogue scales and performed bead intubation coordinometry (BIC) six times each day (on waking up, at bedtime, and every four hours in between) for 10 consecutive days. Each series (using data with the trend removed if there was a significant trend) was analysed for circadian rhythmicity by a cosine vector technique (single cosinor). With individual data expressed as the percentage of the mean, group rhythm characteristics at period 24 hours were summarised for each variable by population mean cosinor analysis. RESULTS Individual analyses identified significant circadian rhythms at p<or=0.05 for pain (n=15/21), stiffness (n=16/20), and dexterity (n=18/21), and a significant circadian rhythm on a group basis was identified for pain (p=0.013), stiffness (p<0.001), and dexterity (p<0.001). Pain was least at 1610 and stiffness at 1618. Peak dexterity occurred in mid-afternoon at 1548 and occurred within the 95% confidence interval of least pain (1312-1800) and stiffness (1520-1732). CONCLUSIONS Dexterity was influenced by the patient's level of pain or stiffness, which changed systematically throughout the day. Similar results have been previously reported in 14 patients with rheumatoid arthritis where peak dexterity occurred at 1544 and at 1528 in 14 age and sex matched healthy controls. The predictability of rhythmic variation in pain, stiffness, and dexterity has implications for scheduling activities of daily living and for timing antirheumatic drug treatment.