Outcomes of secondary hyperparathyroidism in chronic kidney disease and the direct costs of treatment.
BACKGROUND
There has been an emphasis over the last several years to identify and treat chronic kidney disease (CKD) and its complications as they evolve rather than waiting until the patient reaches end-stage renal disease (ESRD), also known as CKD stage 5. The number of patients who will be identified and prescribed therapies for complications such as secondary hyperparathyroidism (SHPT) is greater than initially proposed.


OBJECTIVE
To review the pathways, complications, management, and estimated treatment costs of CKD-related SHPT.


METHODS
An electronic literature search of MEDLINE (January 1980 through January 2007) was conducted for English-language publications using the base search term secondary hyperparathyroidism. To refine subsequent searches, the authors added Boolean operators to the following secondary and tertiary search terms: parathyroid hormone, chronic kidney disease, renal osteodystrophy, adynamic bone disease, vascular calcification, cardiovascular disease, vitamin D, vitamin D analogs, hypercalcemia, hyperphosphatemia, calcimimetics, costs, prevalence, and economics.


RESULTS
The initial MEDLINE search produced 278 relevant articles. After refining the search terms, the authors triaged the results for English-language publications relevant to the discussion of SHPT and its complications in CKD, eliminating 149 publications. The remaining 129 publications were accepted for review. These articles represent a growing body of primarily observational evidence that demonstrates that elevated intact parathyroid hormone (PTH) levels cause deleterious physiological results across a variety of organ systems, including the cardiovascular and skeletal systems. Specific complications associated with SHPT are left ventricular hypertrophy (LVH), renal osteodystrophy (ROD), and extraskeletal calcification. Medical management of the PTH/vitamin D/calcium and phosphorus imbalances in SHPT focus on regulating PTH levels via vitamin D therapy. The class of calcimimetics is a newer treatment modality that has favorable effects on biochemical laboratory values, such as serum calcium and phosphorus levels, but current data do not show differences on hard endpoint patient-oriented outcomes compared with standard generic agents. The direct drug costs in April 2007 U.S. dollars of treating CKD-associated elevations in PTH in predialysis patients range from $8.40 per patient per week ($437 per year) for oral generic calcitriol to $88.90 per patient per week ($4,623 per year) for oral paricalcitol (expressed as 85% of average wholesale price [AWP] for brand drugs or 70% of AWP for generic drugs). The direct drug costs of treating SHPT in hemodialysis patients range from $80.20 per patient per week ($4,170 per year) for generic calcitriol (IV) to $278.46 per patient per week ($14,480 per year) for oral cinacalcet.


CONCLUSIONS
SHPT causes skeletal and cardiovascular complications in CKD patients. Calcitriol therapy is effective in managing PTH levels, but efforts to reduce the associated hypercalcemia and hyperphosphatemia have led to the development of newer, yet more expensive, vitamin D analogs. With the lack of evidence to support comparative superior outcomes in end-organ disease among SHPT therapy alternatives, future research is still needed to clearly identify which newer agents are most competitive with the historical gold standard of calcitriol therapy.
Joy
Melanie S
MS
School of Medicine, Division of Nephrology and Hypertension, UNC Kidney Center, Univerisity of North Carolina, Chapel Hill, NC 27599-7155, USA. melanie_joy@med.unc.edu
Karagiannis
Paul C
PC
Peyerl
Fred W
FW
D002117:Calcitriol / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology; D012080:Chronic Kidney Disease-Mineral and Bone Disorder / Q000453:epidemiology / Q000209:etiology; D000069449:Cinacalcet; D003362:Cost-Benefit Analysis; D016527:Drug Costs / Q000706:statistics & numerical data; D004872:Ergocalciferols / Q000627:therapeutic use; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000191:economics* / Q000209:etiology / Q000628:therapy*; D009281:Naphthalenes / Q000627:therapeutic use; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism; D016105:Parathyroidectomy; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000191:economics* / Q000628:therapy; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000191:economics / Q000627:therapeutic use*; D014815:Vitamins / Q000191:economics / Q000627:therapeutic use*
D004872:Ergocalciferols; D009281:Naphthalenes; D010281:Parathyroid Hormone; D014815:Vitamins; D014807:Vitamin D; C042533:1 alpha-hydroxyergocalciferol; C084656:paricalcitol; D002117:Calcitriol; D000069449:Cinacalcet