title: Parathyroid hormone change after cinacalcet initiation and one-year clinical outcome risk: a retrospective cohort study.
abstract: BACKGROUND
  Cinacalcet reduces parathyroid hormone (PTH) levels in patients receiving hemodialysis, but no non-experimental studies have evaluated the association between changes in PTH levels following cinacalcet initiation and clinical outcomes. We assessed whether short-term change in PTH levels after first cinacalcet prescription could serve as a surrogate marker for improvements in longer-term clinical outcomes.
  
  
  METHODS
  United States Renal Data System data were linked with data from a large dialysis organization. We created a point prevalent cohort of adult hemodialysis patients with Medicare as primary payer who initiated cinacalcet November 1, 2004-February 1, 2007, and were on cinacalcet for ≥ 40 days. We grouped patients into quartiles of PTH change after first cinacalcet prescription. We used Cox proportional hazard modeling to evaluate associations between short-term PTH change and time to first composite event (hospitalization for cardiovascular events or mortality) within 1 year. Overall models and models stratified by baseline PTH levels were adjusted for several patient-related factors.
  
  
  RESULTS
  For 2485 of 3467 included patients (72%), PTH levels decreased after first cinacalcet prescription; for 982 (28%), levels increased or were unchanged. Several characteristics differed between PTH change groups, including age and mineral-and-bone-disorder laboratory values. In adjusted models, we did not identify an association between greater short-term PTH reduction and lower composite event rates within 1 year, overall or in models stratified by baseline PTH levels.
  
  
  CONCLUSIONS
  Short-term change in PTH levels after first cinacalcet prescription does not appear to be a useful surrogate for longer-term improvements in cardiovascular or survival risk.
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota. WStPeter@cdrg.org.|University of Minnesota, College of Pharmacy, Minneapolis, Minnesota. WStPeter@cdrg.org.
authors.forename: Wendy L
authors.initials: WL
authors.lastname: St Peter
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota. ayusuf@cdrg.org.|University of Minnesota, College of Pharmacy, Minneapolis, Minnesota. ayusuf@cdrg.org.
authors.forename: Akeem A
authors.initials: AA
authors.lastname: Yusuf
authors.affiliation: Center for Observational Research, Amgen Inc., Thousand Oaks, California. dot@amgen.com.
authors.forename: Thy
authors.initials: T
authors.lastname: Do
authors.affiliation: Center for Observational Research, Amgen Inc., Thousand Oaks, California. lowek@amgen.com.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Lowe
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota. jliu@cdrg.org.
authors.forename: Jiannong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota. knieman@cdrg.org.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Nieman
authors.affiliation: Center for Observational Research, Amgen Inc., Thousand Oaks, California. bradbury@amgen.com.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Bradbury
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota. acollins@cdrg.org.|University of Minnesota, College of Pharmacy, Minneapolis, Minnesota. acollins@cdrg.org.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Collins
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000069449:Cinacalcet / Q000627:therapeutic use*; D015331:Cohort Studies; D016208:Databases, Factual; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000188:drug therapy* / Q000209:etiology / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000150:complications / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000187:drug effects; D010281:Parathyroid Hormone / Q000097:blood*; D011379:Prognosis; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome; D014481:United States
chemical_list: D010281:Parathyroid Hormone; D000069449:Cinacalcet