Metabolic correlates of obesity and radiographic features of knee osteoarthritis: data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE

To examine the relationship between metabolic correlates of obesity and radiographic knee osteoarthritis (OA).

METHODS

We included 464 Caucasian men and 275 Caucasian women aged 40 years and above who were participants in the Baltimore Longitudinal Study of Aging. Subjects had bilateral anteroposterior standing knee radiographs read for features of OA using Kellgren-Lawrence scales. Resting blood pressure, fasting lipids, 2 h oral glucose tolerance test, and anthropometric measurements were obtained at the same visit as the knee radiograph. Metabolic correlates of obesity were compared between subjects with Kellgren-Lawrence grade > or = 2 (definite knee OA) and grade 0 (normal radiograph) by sex.

RESULTS

Both men and women with knee OA had higher unadjusted systolic blood pressure than those with normal knee radiographs; unadjusted measures of glucose metabolism and lipids did not vary by presence of knee OA in men or women. After adjustment for age and obesity, systolic blood pressure did not vary by presence of knee OA in men. While women with knee OA did have higher adjusted mean systolic blood pressure than women with normal radiographs (127 +/- 2.4 vs 120 +/- 2.2 mm Hg; p = 0.04), both values were within normal range. Unexpectedly, men with knee OA had lower adjusted mean 2 h glucose levels compared to men without OA (7.5 +/- 0.2 vs 8.4 +/- 0.2 mmol/l; p = 0.01). Other adjusted variables did not differ by presence of knee OA.

CONCLUSION

These data do not support the hypothesis that metabolic correlates of obesity are independently associated with radiographic knee OA after adjustment for age and obesity.