Treatment of hyperphosphatemia in hemodialysis patients: The Calcium Acetate Renagel Evaluation (CARE study)

Background. Hyperphosphatemia underlies development of hyperparathyroidism, osteodystrophy, extraosseous calcification, and is associated with increased mortality in hemodialysis patients. Methods. To determine whether calcium acetate or sevelamer hydrochloride best achieves recently recommended treatment goals of phosphorus less than or equal to5.5 mg/dL and Ca x P product less than or equal to55 mg(2)/dL(2), we conducted an 8-week randomized, double-blind study in 100 hemodialysis patients. Results. Comparisons of time-averaged concentrations (weeks I to 8) demonstrated that calcium acetate recipients had lower serum phosphorus (1.08 mg/dL difference, P = 0.0006), higher serum calcium (0.63 mg/dL difference, P < 0.0001), and lower Ca x P (6.1 mg(2)/dL(2) difference, P = 0.022) than sevelamer recipients. At each week, calcium acetate recipients were 20% to 24% more likely to attain goal phosphorus [odds ratio (OR) 2.37, 95% CI 1.28-4.37, P = 0.0058], and 15% to 20% more likely to attain goal Ca x P (OR 2.16, 95% CI 1.20-3.86, P = 0.000). Transient hypercalcemia occurred in 8 of 48 (16.7%) calcium acetate recipients, all of whom received concomitant intravenous vitamin D. By regression analysis hypercalcemia was more likely with calcium acetate (OR 6.1,95% CI 2.8-13.3, P < 0.0001). Week 8 intact PTH levels were not significantly different. Serum bicarbonate levels were significantly lower with sevelamer hydrochloride treatment (P < 0.000 1). Conclusion. Calcium acetate controls serum phosphorus and calcium-phosphate product more effectively than sevelamer hydrochloride. Cost-benefit analysis indicates that in the absence of hypercalcemia, calcium acetate should remain the treatment of choice for hyperphosphatemia in hemodialysis patients.