Aims of the study: To examine the clinical and demographic correlates of pain intensity in patients with hip and knee osteoarthritis (OA).
Patients and methods: In a national cross-sectional survey, 1811 general practitioners recruited and assessed 5324 patients with hip and knee OA. The patients rated the intensity of pain at rest, on movement over the last 24 hours, and during the last 8 days on 11-point numeric rating scales. The patients also completed the Western Ontario and McMaster Universities Osteoarthritis Index. Clinical and demographic correlates of pain intensity and function were investigated by univariate, stepwise multiple logistic regression and odds ratio analyses.
Results: Data for 4598 patients were analyzed (86.4% of surveyed patients). The mean pain intensity was 4.1+/-2.2 at rest, 5.9+/-1.8 on movement during the last 24 hours, and 5.1+/-1.7 during the last 8 days. Pain on movement during the last 24 hours and during the last 8 days showed a strong positive correlation (r=0.78; P<0.0001), which suggests that the most of the latter pain was related to movement. Patients with knee or hip OA did not differ in pain intensity, but patients with both joints affected rated pain intensity significantly higher than did those with only 1 affected joint [4.6+/-2.1, 6.3+/-1.8, and 5.5+/-1.6, for the 3 pain assessments, respectively (P>0.01)]. Patients with high pain ratings were more likely to be women, be older than 75 years, and have a body mass index of greater than 40 kg/m. In addition, patients who were retired, unemployed, farmers, or widowed, or had a long duration of OA gave high pain ratings. Patients with regular physical activities reported less intense pain.
Conclusions: Pain intensity ratings for patients with lower limb OA differed significantly with respect to sex, age, body mass index, physical activity, professional activity, marital status, and conditions of assessment.