Calcium-mediated parathyroid hormone suppression to assess progression of secondary hyperparathyroidism during treatment among incident dialysis patients

Cinacalcet plus vitamin D versus vitamin D alone for the treatment of secondary hyperparathyroidism in patients undergoing dialysis: a meta-analysis of randomized controlled trials

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a common and serious complication of chronic kidney disease, particularly in end-stage renal disease. Currently, both cinacalcet and vitamin D are used to treat SHPT via two different mechanisms, but it is still unclear whether the combination use of these two drugs can be a safe and effective alternative to vitamin D alone. Therefore, the aim of this meta-analysis was to assess the efficacy and safety of cinacalcet plus vitamin D in the treatment of SHPT.

METHODS

Four electronic databases, including PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, were searched for eligible publications. All randomized-controlled trials comparing cinacalcet plus vitamin D with vitamin D alone in SHPT patients undergoing dialysis were included. Mean difference (MD) with 95% confidence intervals (CIs) and risk ratios (RRs) with 95% CIs were calculated using a random-effects model or fixed-effects model. Sensitivity analysis was conducted by removing any one study successively to estimate the stability of the pooled results, and subgroup analysis was carried out to explore potential sources of heterogeneity, and funnel plots were used to test publication bias.

RESULTS

A total of 8 randomized-controlled trials involving 1480 patients were included in the study. Compared with vitamin D treatment, the combination use of cinacalcet and vitamin D significantly lowered serum calcium (MD - 0.82, 95% CI - 1.02 to - 0.61, P < 0.001), phosphorus (MD - 0.57, 95% CI - 0.97 to - 0.18, P = 0.005), and calcium × phosphorus product (MD - 9.41, 95% CI - 10.00 to - 8.82, P < 0.001). However, there was no difference in serum parathyroid hormone (PTH, MD 43.99, 95% CI - 49.22 to 137.20, P = 0.35), ≥ 30% reduction in PTH (RR 1.02, 95% CI 0.69-1.52, P = 0.91), and PTH achieve 150-300 pg/ml (RR 0.88, 95% CI 0.68-1.15, P = 0.35). Moreover, the combination therapy did not increase the risk of all adverse events, all-cause mortality, diarrhea, muscle spasms, and headache (all P > 0.05), but had a higher risk of hypocalcemia (RR 17.98, 95% CI 5.68-56.99, P < 0.001), and nausea or vomiting (RR 3.47, 95% CI 2.25-5.35, P < 0.001).

CONCLUSIONS

In comparison with vitamin D alone, the combination use of cinacalcet and vitamin D significantly lowered serum calcium, phosphorus, and the calcium × phosphorus product, and did not increase the risk of all adverse events, all-cause mortality, diarrhea, muscle spasms, and headache, whereas had no effect on serum PTH and increased the risk of hypocalcemia and nausea or vomiting. Future studies are needed to assess the effects of cinacalcet plus vitamin D on PTH level, cardiovascular events, and other clinical outcomes in larger samples with longer durations.

A Randomized Trial of Cinacalcet versus Vitamin D Analogs as Monotherapy in Secondary Hyperparathyroidism (PARADIGM)

BACKGROUND AND OBJECTIVES

Direct comparison of cinacalcet and vitamin D analogs as monotherapies to lower parathyroid hormone (PTH) levels has not been undertaken.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective, multicenter, phase 4, randomized, open-label study that enrolled participants from 2010 to 2012. Adult participants (n=312) on hemodialysis with PTH >450 pg/ml were randomized 1:1 to 12 months of treatment with either cinacalcet (n=155) or vitamin D analogs (n=157) to evaluate the mean percentage change in plasma PTH level (primary end point) and the proportion of participants achieving plasma PTH <300 pg/ml or a ≥30% decrease in PTH (secondary end points). A preplanned analysis to determine whether there were important region-by-treatment interactions was also undertaken.

RESULTS

Baseline mean PTH was 846 pg/ml (n=155) for cinacalcet and 816 pg/ml (n=157) for vitamin D analog therapy. The mean (95% confidence interval) percentage change from baseline in PTH was -12.1% (-20.0% to -4.1%) in the cinacalcet arm and -7.0% (-14.9% to 0.8%) in the vitamin D analog arm, a difference of -5.0% (-15.4% to 5.4%) (P=0.35). Similarly, there was no difference in achievement of secondary efficacy end points between arms (19.4% and 15.3% of participants with PTH≤300 pg/ml and 42.6% and 33.8% of participants had a PTH reduction >30% in the cinacalcet and vitamin D analog arms, respectively). A prespecified analysis revealed a large treatment-by-region interaction, with nominally greater response to cinacalcet compared with vitamin D analogs in non-United States participants (US versus non-US participants, P<0.001). Hypocalcemia was more common in the cinacalcet arm, whereas hypercalcemia and hyperphosphatemia occurred more often in the vitamin D analog arm.

CONCLUSIONS

Participants had similar modest reductions in PTH with either cinacalcet or vitamin D analog monotherapy over 52 weeks of treatment, but effects varied by region. Treatments differed with regard to effect on calcium and phosphorus levels.