Parathyroid hormone change after cinacalcet initiation and one-year clinical outcome risk: a retrospective cohort study.

Wendy L St Peter,Brian D Bradbury,Allan J Collins,Kimberly M Nieman,Kimberly A Lowe,Thy Do,Jiannong Liu,Akeem A Yusuf

doi:10.1186/s12882-015-0030-8

Abstract

BackgroundCinacalcet 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.MethodsUnited 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.ResultsFor 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.ConclusionsShort-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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0030-8) contains supplementary material, which is available to authorized users.

Highlights

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 evaluated patient characteristics at baseline for each group: age, race, sex, cause of ESRD, dialysis duration, body mass index (BMI), Secondary hyperparathyroidism (SHPT)-related laboratory values (PTH, pg/mL; calcium, mg/dL; phosphorus, mg/dL), Dialysis dose (Kt/V), hospital days, phosphate binder use at the time of first cinacalcet prescription, and 11 comorbid conditions
Patients whose PTH levels decreased were stratified into four groups based on the quartiles of percentage change from before to after cinacalcet initiation

Summary

Introduction

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. No studies have evaluated the association between shortterm changes in PTH following first cinacalcet prescription and whether these early changes relate to clinical outcomes. It would be useful to know whether PTH change following cinacalcet prescription over a relatively short time period is associated with important outcomes such as mortality or cardiovascular events. We assessed whether short-term change in PTH levels after first cinacalcet prescription could be used as a surrogate for longer-term improvements in clinical outcomes

Methods

Results

Discussion

Conclusion