Association Between Bone Mineral Density and the Use of Nonsteroidal Anti-Inflammatory Drugs and Aspirin: Impact of Cyclooxygenase Selectivity

BMD was examined in users of NSAIDs (by COX selectivity) and aspirin in the Health ABC cohort (n = 2853). Significantly higher BMD was found in users of relative COX-2 selective NSAIDs with aspirin (COX-2/ASA) compared with nonusers. This suggests a role for COX-2/ASA in osteoporosis. Introduction: The purpose of this study was to determine the relationship of nonsteroidal anti-inflammatory drug (NSAID) use, by cyclo-oxygenase selectivity (COX), and aspirin use on bone mineral density (BMD) in participants from the Health, Aging, and Body Composition (Health ABC) population-based cohort. It is known that NSAIDs inhibit the COX enzyme and decrease production of prostaglandins, which are involved in regulation of bone turnover. COX has two isoforms, COX-1 and COX-2. Production of prostaglandins associated with bone loss is primarily mediated through the COX-2 pathway. In addition, aspirin may have effects on bone independent of the prostaglandin pathway. Materials and Methods: NSAID (by COX selectivity) and aspirin use and BMD were assessed in 2853 adults (49.5% women, 50.5% men; 43.1% black, 56.9% white; mean age: 73.6 years) from the Health ABC cohort. For the purposes of this analysis, relative COX-1 selective NSAIDs were defined as having a ratio of COX-1 IC₅₀ to COX-2 IC ₅₀ of > 1 in whole blood, and relative COX-2 selective NSAIDs were defined as having a ratio of COX-1 IC₅₀ to COX-2 IC50 of <1 in whole blood. Analysis of covariance was used to compare BMD across each NSAID use and aspirin use category adjusting for age, race, gender, weight, height, study site, calcium and vitamin D supplementation, Womac score, history of rheumatoid arthritis, history of arthritis other than rheumatoid, and smoking status. Results: After adjustment for possible confounders, current use of relative COX-2 selective NSAIDs with aspirin was associated with higher BMD at the whole body (4.2%, 1.2-7.3 CI) and total hip (4.6%, 0.5- 8.8 CI) by DXA and at both trabecular (34.1%, 15.4-52.7 CI) and cortical spine (12.8%, 2.3-23. 3 CI) by quantitative computed tomography. Conclusions: Our data suggest that the combination of relative COX-2 selective NSAIDs and aspirin is associated with higher BMD at multiple skeletal sites in men and women.