Moderate chronic kidney disease in women is associated with fracture occurrence independently of osteoporosis

Background: Chronic kidney disease (CKD) is associated with increased risk of fragility fracture but whether this is independent of osteoporosis is unclear. Methods: We conducted a retrospective cross-sectional study of 1,702 female patients referred for dual-energy X-ray absorptiometry (DXA) scanning (Lunar IDXA) between September 2006 and April 2007. Estimated glomerular filtration rate (eGFR; ml/min/1.73 m²) by Modification of Diet in Renal Disease was calculated within 1 year (median interval 4 weeks) of the DXA scan. The independent association of self-reported fracture occurrence with eGFR category was assessed using multivariate logistic regression. Results: Mean age (SD) was 61.7 (10.8) years; mean eGFR (SD) was 68.8 (12.2). The percentages of subjects with an eGFR of 75-89, 60-74, 30-59 and <30 was 34, 45, 20 and 0.8%, respectively. Forty-seven percent had osteoporosis. Mean T scores for the above eGFR categories were -2.2, -2.3, -2.5 and -3.0, respectively (p trend <0.001). Osteoporosis was significantly associated with eGFR on univariate analysis but not following adjustment for age. The percentage of patients with a fracture (29%) and with multiple prior fractures (3.5%) was higher at lower eGFR (p < 0.001, χ² test). The adjusted odds ratios (95% confidence interval) of any prior fracture for eGFR 75-89, 60-74 and 30-59 were 1.0 (reference), 1.2 (0.9-1.6) and 1.4 (1.0-1.9), respectively, adjusting simultaneously for age, T score, risk factors and treatment for osteoporosis. Conclusion: Moderate CKD is a significant independent predictor of fracture occurrence.