Association of nitrate use with risk of new radiographic features of hip osteoarthritis in elderly white women: the study of osteoporotic fractures.

Objective: To examine the association between nitrate medication use and the development of new radiographic findings of hip osteoarthritis (OA) in elderly women.

Methods: Pelvic radiographs were obtained at baseline and a mean of 8.3 years later in 5,987 women, age > or =65 years at the baseline examination of the Study of Osteoporotic Fractures. Atlas-standardized individual radiographic features (IRFs) of OA were assessed and minimal joint space was measured on paired films. New radiographic findings of hip OA were defined as the development in hips free of these findings at baseline: 1) joint space narrowing (JSN), which consisted of either a MJS < or =1.5 mm or an IRF score indicating lateral JSN > or =2 or medial JSN > or =3; 2) an IRF score for osteophytes of > or =2 in any location; or 3) a summary grade of 2 or more (at least 2 IRFs present). Nitrate use was recorded by interview at years 6 and 8. Logistic and linear regression analyses were performed to determine the association of nitrate use with new radiographic findings of hip OA, adjusting for age, weight, height, bone mineral density, and estrogen.

Results: Compared with no reported use of nitrates, we found significant associations between use of nitrates at 1 clinic visit and new JSN (odds ratio [OR] 1.94, 95% confidence interval [95% CI] 1.18-3.17, P = 0.009), new osteophyte formation (OR 1.70, 95% CI 1.03-2.88, P = 0.04), and any new radiographic finding of hip OA or total hip arthroplasty for OA (OR 1.71, 95% CI 1.16-2.52, P = 0.007). Any nitrate use was associated with an increased risk of developing summary grade 3 or greater hip OA (OR 1.84, 95% CI 1.03-3.31, P = 0.041), but not with any other incident findings of OA.

Conclusion: Older women using nitrates may have an increased risk of developing new radiographic findings of hip OA.