title: Management of serum calcium reductions among patients on hemodialysis following cinacalcet initiation.
abstract: OBJECTIVE
  Cinacalcet is indicated for treatment of secondary hyperparathyroidism in patients receiving hemodialysis. Cinacalcet reduces serum calcium concentrations by decreasing parathyroid hormone secretion, but the frequency and degree of calcium reduction following cinacalcet initiation, subsequent physician response, and ultimate calcium recovery in clinical practice are not well described.
  
  
  METHODS
  Patients receiving hemodialysis at a large dialysis organization who enrolled in the organization's prescription benefits service and initiated cinacalcet at serum calcium ≥8.4 mg/dL were studied (N = 13 723). Patients were categorized by whether they experienced a reduction in calcium to <8.4 mg/dL and to what level (<7.5, 7.5-7.9, and 8.0-8.3 mg/dL). Baseline characteristics, frequency of subsequent intervention, and calcium recovery were compared.
  
  
  RESULTS
  Of those who experienced a reduction in calcium to <8.4 mg/dL (n = 6437 [46.9%]), 6.6% had calcium <7.5 mg/dL and 24.5% had calcium 7.5-7.9 mg/dL, while the majority (68.9%) had a level of 8-8.3 mg/dL. Higher baseline parathyroid hormone and alkaline phosphatase were associated with lower resultant calcium. Among patients with calcium reductions, 45.6-63.5% received one or more directed clinical therapeutic responses, including 15.6-28.4% for whom cinacalcet was discontinued; the majority of patients recovered to calcium ≥8.4 mg/dL within 90 days of first detection. Only modest differences in recovery were noted between patients who did and did not receive any therapeutic response and patients who did and did not discontinue cinacalcet.
  
  
  CONCLUSIONS
  Serum calcium reductions following cinacalcet initiation were common; declines <7.5 mg/dL were infrequent. Calcium recovery occurred in the majority of patients, with or without therapeutic intervention.
authors.affiliation: DaVita Clinical Research, Minneapolis, MN, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Brunelli
authors.affiliation: Amgen Inc., Thousand Oaks, CA, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dluzniewski
authors.affiliation: Amgen Inc., Thousand Oaks, CA, USA.
authors.forename: Kerry
authors.initials: K
authors.lastname: Cooper
authors.affiliation: Amgen Inc., Thousand Oaks, CA, USA.
authors.forename: Thy P
authors.initials: TP
authors.lastname: Do
authors.affiliation: DaVita Clinical Research, Minneapolis, MN, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Sibbel
authors.affiliation: Amgen Inc., Thousand Oaks, CA, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Bradbury
mesh_terms: D057966:Calcimimetic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood*; D000069449:Cinacalcet / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D006435:Renal Dialysis / Q000009:adverse effects; D012189:Retrospective Studies
chemical_list: D057966:Calcimimetic Agents; D010281:Parathyroid Hormone; D002118:Calcium; D000069449:Cinacalcet
keywords: hypocalcemia; mineral bone disease; pharmacoepidemiology; secondary hyperparathyroidism