Does baseline physical activity level impact on change in knee pain following patient education and supervised exercise therapy? A prospective cohort study of 12,800 participants with knee OA from the Danish GLA:D® registry

Abstract

Purpose: To investigate the impact of self-reported physical activity level at baseline on change in knee pain after participation in an 8-week combined patient education and supervised neuromuscular exercise therapy program. Methods: Data from the Danish Good Life with osteoArthritis in Denmark (GLA:D®) registry were used. Participants with knee OA from which self-reported physical activity and knee pain assessments at baseline and at 3 months were available were included. Physical activity at baseline was assessed by the question “How often do you usually exercise at a level where you get short of breath or sweat?”. We classified participants in four physical activity groups: sedentary (i.e., participants did not sweat or were not short of breath more often than twice a month), insufficiently physically active (i.e., participants did sweat or were short of breath once weekly), adequately physically active (i.e., participants did sweat or were short of breath 2-3 times a week) and very physically active (i.e., participants did sweat or were short of breath more than 3 times a week). Average knee pain during the last month was measured at baseline and 3 months follow-up, using a visual analogue scale (VAS) were 100 corresponds to ‘maximum pain’ and 0 to ‘no pain’. The main outcome measure of this study was change in knee pain over 3 months. A reduction of 10 on the 0-100 scale was considered clinically important. Impact of baseline physical activity level on change in knee pain was estimated for the entire cohort using a mixed-effect model adjusting for age, sex and body mass index (BMI). Secondly, this step was repeated separately for men and women. Results: 12,800 people with knee OA were included in the analysis (mean age (SD) 64 (9.8) years, 72% women, mean BMI (SD) 28 (5.2)). Mean (SD) knee pain on the VAS was 48 (22) at baseline (Table 1). Overall, there was a reduction of knee pain (mean (SD)) of 13.1 mm (22.9). When stratified by sex, women had a greater knee pain reduction than men, -14.1 mm vs. -10.3 mm (between group difference -3.6 mm; 95%CI -4.6 to -2.5) P<0.01). Women who were physically active once weekly had a greater knee pain reduction than sedentary women, -14.9 mm vs. -13.5 mm (between group difference -1.7 mm; 95%CI -3.4 to -0.02) P = 0.047) (Table 2). However, these differences were not considered clinically relevant. No other differences in pain relief between groups with different baseline physical activity level were seen for women, men or the total group. Conclusions: People with knee OA experienced a clinically relevant pain relief from participating in the 8-week GLA:D® program, regardless of their baseline physical activity level.Table 1Baseline characteristics of the participants. Values represents mean (standard deviations)All individualSedentaryPhysically active once weeklyPhysically active 2–3 times weeklyPhysically active > 3 times weeklyn = 12,800n = 3833n = 2503n = 4575n = 1889Age (years)All individual64 (9.8)63 )10.0)64 (9.8)64 (9.7)64 (9.2)Men65 (9.6)64 (9.7)65 (9.9)65 (9.5)66 (9.7)Women64 (9.8)63 (10.1)64 (9.8)64 (9.8)64 (9.0)Sex (n (%)Men3452 (28%)1084 (28%)583 (24%)1238 (27%)547 (29%)Women9348 (72%)2749 (72%)1920 (76%)3337 (73%)1342 (71%)BMIAll individual28 (5.2)30 (5.7)29 (5.2)28 (4.9)28 (4.8)Men29 (4.5)30 (5.1)29 (4.5)28 (4.1)28 (4.2)Women28 (5.5)30 (5.9)29 (5.4)28 (5.2)27 (5.0)VAS pain (0-100)All individual48 (22.0)51 (22.3)49 (21.5)47 (21.8)48 (22.6)Men45 (21.6)47 (21.9)46 (21.0)43 (21.3)44 (21.9)Women50 (22.0)53 (22.2)50 (21.6)48 (21.8)50 (22.7) Open table in a new tab Table 2Change in knee pain changes (VAS, 0-100 mm) from an eight-week combined patient educationSedentaryPhysically active once weeklyPhysically Active 2-3 times weeklyPhysically Active >3 times weeklySedentary vs. Physically active once weeklySedentary vs. Physically active 2-3 times weeklySedentary vs. Physically Active >3 times weeklyMean (SD)Mean (SD)Mean (SD)Mean (SD)Non-adjustedAdjustedNon-adjustedAdjustedNon-adjustedAdjustedAll participants (n = 12,800)VAS (mm)−12.9 (23.9)−13.8 (22.6)−12.8 (22.5)−13.1 (22.6)0.190.1300.970.6210.740.340Men (n = 3,452)VAS (mm)−11.2 (22.2)−10.3 (20.6)−10.0 (20.8)−9.2 (23.1)0.480.6740.290.5020.160.357Women (n = 9,348)VAS (mm)−13.5 (24.5)−14.9 (23.1)−13.9 (23.0)−14.7 (22.2)0.100.0470.590.3140.220.099 Open table in a new tab