Relationship between age, renal function and bone mineral density in the US population.

Bisphosphonate drugs for treating osteoporosis are excreted by the kidney. However, many of the major trials on efficacy and safety of the bisphophonates for treating osteoporosis excluded patients with significant renal compromise. Since both osteoporosis and renal insufficiency become more prevalent with age, it seems prudent for physicians to be aware of the prevalence of renal dysfunction in patients with osteoporosis who are candidates for treatment with bisphosphonates. Data on 13,831 men and women aged 20+ from the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) were used to study the occurrence of compromise in renal clearance function in men and women with osteopenia and osteoporosis. To estimate creatinine clearance (CCr), a measure of renal function, serum creatinine (sCr), weight and age were inserted into the Cockcoft-Gault (C-G) formula. The World Health Organization gender specific bone mineral density (BMD) cut-offs were used to define the populations with osteopenia and osteoporosis. For women ages 20-80+ with osteoporosis, the percent prevalence (95% CI) for mild to moderate compromise of CCr </=60 ml/min is estimated to be 85% (79%, 91%) and for severe renal compromise of CCr <35 ml/min to be 24% (19%, 29%). In women with osteoporosis and severe compromise, the age specific prevalence is negligible through ages 50-59 and then rises steeply to 54% (46%, 62%) for ages 80+. Similarly, in women with osteopenia and severe renal compromise, the age specific prevalence is also negligible through ages 50-59 and then rises to 37% (28%, 45%) for ages 80+. Lower prevalence estimates hold for men with about 11% of men with osteoporosis having severe renal compromise as compared to 24% for women. These data suggest that there is a substantial prevalence of candidates for treatment of osteoporosis and osteopenia who have significant renal compromise but for whom there is a dearth of clinical trial data on the impact of treatment.