Association between metabolic factors and knee osteoarthritis in women: the Chingford Study

Several studies have shown an association with density and knee osteoarthritis (OA), however the role of other metabolic factors is unclear, with conflicting data in the literature. We studied the association between metabolic risk factors and k nee OA in women in the general population.

One thousand three women aged 45-64 from the Chingford population study completed risk factor questionnaires. Current blood pressure and ever hypertension were noted and fasting blood glucose, serum cholesterol, triglycerides, high density lipoprotein( HDL), and uric acid levels were measured. AP weight bearing radiographs were available in 979 women and scored using the Kellgren and Lawrence system. Grade 2+ (definite osteophytes) was used a definition of knee OA. Odds ratios (OR) and 95% confidence intervals were calculated for risk of knee OA in highest tertile versus lowest for death risk factor. All OR were adjusted for age and body mass index as potential confounders for OA.

Radiological evidence of knee OA was found in 118 women (12%). For knee OA in either knee the variables significantly associated were raised blood glucose OR = 1.95 (1.08-3.59), and moderately raised serum cholesterol OR = 2.06 (1.06-3.98). For symptomatic women (n = 58) raised blood glucose OR = 2.77 (1.13-6.76), and use of diuretics OR = 2.27 (1.11-4.65) were significantly associated. For bilateral knee disease (n = 55) significant associations were found for ever hypertension OR = 3.02 (1.51-6.06), subjects taking diuretics OR = 2.84 (1.37-5.89), and both high and moderately raised serum cholesterol OR = 3.91 (1.07-14.25), and OR = 3.63 (1.00-13.88), respectively. In all categories of knee OA serum uric acid was nonsignificantly increased. No association was found with raised triglyceride or HDL levels or with current systolic blood pressure. Further adjustment for physical activity and social class did not affect the results.

These data suggest that hypertension, hypercholesterolemia, and blood glucose are associated with both unilateral and bilateral knee OA independent of obesity, and support the concept that OA has an important systemic and metabolic component in its etiology.