Table 2 Studies examining the effect of BMI on the relationship between physical activity and risk for developing knee OA
Author (year) | Study design/participants | Measure(s) of OA | Measure(s) of physical activity | Results: effect of BMI |
|---|---|---|---|---|
Studies investigating self-reported symptomatic OA | ||||
   Felson et al. (2007) [11] | 9-year longitudinal cohort study/1,279 participants from the Framingham Offspring cohort | Self-reported, symptomatic | Self-reported; frequency, type, intensity | Overall results are presented in Table 1 |
|  |  |  |  | Among persons with BMI above the median, there was no relationship between the risk for knee OA and the following: walking (≥6 miles/week; OR 0.84, 95% CI 0.37 to 1.92); working up a sweat (≥3 times/week; OR 1.04, 95% CI 0.55 to 1.96); and activity level compared with peers (more active; OR 0.63, 95% CI 0.35 to 1.16) |
Studies investigating self-reported physician diagnosed OA | ||||
   Hootman et al. (2003) [10] | 12.8-year cohort study/5,284 participants from the Cooper Clinic | Self-reported, physician diagnosed | Self-reported; joint stress physical activity score (intensity, frequency, duration and type) | Increasing levels of the joint stress physical activity score were not associated with an increased risk for hip/knee OA for both men (high level; OR 1.07, 95% CI 0.47 to 2.42) and women (high level: OR 1.31, 95% CI 0.92 to 1.87) |
| Â | Â | Â | Â | BMI did not modify the relationship between moderate physical activity and risk for knee OA for both men (OR 1.07, 95% CI 1.03 to 1.11) and women (OR 1.12, 95% CI 1.06 to 1.19) |
Radiographic studies investigating structural OA | ||||
   Felson et al. (2007) [11] | 9-year longitudinal cohort study/1,279 participants from the Framingham Offspring cohort | Radiographic, structural | Self-reported; frequency, type, intensity | Overall results presented in Table 1 |
|  |  |  |  | Among persons with BMI above the median, there was no relationship between the risk of radiographic knee OA and the following: walking (≥6 miles/week; OR 0.95, 95% CI 0.55 to 1.62); working up a sweat (≥3 times/week; OR 1.22, 95% CI 0.67 to 2.21); and activity level compared with peers (more active; OR 0.82, 95% CI 0.48 to 1.40) |
   McAlindon et al. (1999) [14] | 8-year longitudinal cohort study/473 participants from the Framingham Heart Study cohort | Radiographic, structural | Self-reported: Framingham physical activity index; activity type, duration | The number of hours per day of heavy physical activity was associated with risk for knee OA (≥4 hours heavy activity/day compared with no heavy activity; OR 7.0, 95% CI 2.4 to 20 [P = 0.0002]) |
|  |  |  |  | Risk for OA was greatest among individuals in the upper tertile of BMI (≥3 hours/day of heavy physical activity; OR 13.0, 95% CI 3.3 to 51) |
   Kujala et al. (1995) [15] | Retrospective cohort study/117 male former top-level athletes | Radiographic, structural | Self-reported; parameters not-specified | Risk for knee OA was increased in athletes with a higher BMI at age 20 years (OR 1.76/unit increase, 95% CI 1.26 to 2.45) |