Dynamics of cinacalcet use and biochemical control in hemodialysis patients: a retrospective New-user cohort design.
BACKGROUND
Cinacalcet is used to treat secondary hyperparathyroidism among hemodialysis patients. Large-scale epidemiologic studies describing patterns of cinacalcet use, effects on parathyroid hormone (PTH), calcium, and phosphorous levels, and predictors of discontinuation have not been previously reported.


METHODS
This retrospective cohort study used a clinical database of a large U.S. dialysis provider (2007-2010) merged with administrative data from the United States Renal Data System. Among new users of cinacalcet with Medicare coverage, trends in PTH, calcium, and phosphorus were measured in 30-day intervals following cinacalcet initiation.


RESULTS
Seventeen thousand seven hundred sixty-three eligible initiators contributed 111,047 30-day follow-up intervals. Of these, 56 % discontinued cinacalcet by month 4. Of those discontinuing, 76.3 % reinitiated. Mean values of PTH, calcium, and phosphorus decreased to recommended levels within 4 months following initiation. Proximal PTH levels < 150 pg/mL were associated with discontinuation: HR = 1.23 (95 % CI: 1.12, 1.36), whereas low calcium (< 7.5 mg/dL) was suggestive of an association, HR = 1.09 (95 % CI 0.91, 1.32). Being in the Part D gap period increased discontinuation risk: HR = 1.09 (95 % CI: 1.03, 1.16). Low-income subsidy status decreased discontinuation risk: HR = 0.77 (95 % CI 0.69, 0.86). Predictors of reinitiation included low-income subsidy, HR = 1.32 (95 % CI 1.22, 1.43); higher albumin level, HR = 1.23 (95 % CI 1.10, 1.36) and higher calcium level, HR = 1.26 (95 % CI 1.19, 1.33).


CONCLUSIONS
Substantial and expected declines in laboratory values occurred following cinacalcet initiation. Early discontinuation and reinitiation of cinacalcet were common and may have occurred for clinical and economic reasons.
Cecil G. Sheps Center for Health Services Research, University of North Carolina, Chapel Hill, NC, USA. diane.reams@unc.edu.
B Diane
BD
Reams
Amgen, Inc, Thousand Oaks, CA, USA. pdluznie@amgen.com.
Paul J
PJ
Dluzniewski
Amgen, Inc, Thousand Oaks, CA, USA. thypdo@gmail.com.
Thy P
TP
Do
Amgen, Inc, Thousand Oaks, CA, USA. syue@amgen.com.
Susan V
SV
Yue
Amgen, Inc, Thousand Oaks, CA, USA. bradbury@amgen.com.
Brian D
BD
Bradbury
University of North Carolina Kidney Center, UNC School of Medicine, Chapel Hill, NC, USA. abhijit_kshirsagar@med.unc.edu.
Abhijit V
AV
Kshirsagar
Department of Epidemiology, UNC Gillings School of Global Public Health, UNC Chapel Hill, Chapel Hill, NC, USA. abrookhart@unc.edu.
M Alan
MA
Brookhart
D000328:Adult; D000368:Aged; D057966:Calcimimetic Agents / Q000191:economics / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D000069449:Cinacalcet / Q000191:economics / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood* / Q000188:drug therapy*; D007182:Income; D019458:Insurance Coverage; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D054524:Medicare Part D; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000097:blood; D011632:Public Assistance; D006435:Renal Dialysis; D019233:Retreatment / Q000191:economics / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012709:Serum Albumin / Q000378:metabolism; D014481:United States; D028761:Withholding Treatment / Q000191:economics / Q000706:statistics & numerical data
D057966:Calcimimetic Agents; D010281:Parathyroid Hormone; D012709:Serum Albumin; D010758:Phosphorus; D002118:Calcium; D000069449:Cinacalcet