Prescription patterns and mineral metabolism abnormalities in the cinacalcet Era: Results from the MBD-5D study

Background and objectives Prescription patterns for hemodialysis patients with secondary hyperparathyroidism have varied widely since market introduction of cinacalcet. This study examined associations between prescription patterns and subsequent laboratory values. Design, setting, participants, & measurements Using a Mineral and Bone Disorder Outcomes Study for Japanese CKD Stage 5D Patients subcohort, 1716 prevalent hemodialysis patients (4048 sets for repeated measures between January 2008 and July 2009) with an intact parathyroid hormone (iPTH) level >180 pg/ml who used intravenous vitamin D receptor activator (VDRA) without cinacalcet were selected. Prescription patterns were defined based on cinacalcet administration (starting or not) and VDRA dosage change (decreased [<-25%], stable [-25% to 25%], or increased [>25%]). Proportion differences (PDs) were determined for decreasing iPTH levels by at least one category (<180, 180-299, 300-499, and ≥500 pg/ml) and for achieving target phosphorus (3.5-6.0 mg/dl) and calcium (8.4-10.0 mg/dl) levels, adjusting for potential confounders. Results The starting cinacalcet and increased VDRA patterns were associated with decreasing iPTH levels (PD, 0.25 and 0.13; 95% confidence intervals [95% CIs], 0.19-0.31 and 0.09-0.17, respectively); combination use had an additive association (PD, 0.34; 95% CI, 0.20-0.42). The starting cinacalcet and decreased VDRA combination was associated with simultaneously achieving target phosphorus (PD, 0.12; 95% CI: 0.04-0.20) and calcium (PD, 0.09; 95% CI, 0.01-0.17) levels. Conclusions Certain combinations of cinacalcet and VDRA were associated with decreasing iPTH and achieving targets for phosphorus and calcium. Combinations may prove advantageous versus VDRA alone in managing secondary hyperparathyroidism.