Date of publication: April 11, 2014

News & Views

Adherence (Part 2) – Is adherence to phosphate binder therapy associated with improved outcomes?

Research and clinical experience suggests that adherence to phosphate binders is low, but will improving adherence lead to better outcomes? A meta-analysis of 21 studies, in diseases such as HIV, myocardial infarction and type II diabetes, found that “good adherence to drug therapy is associated with positive health outcomes.”[1]  But does similar evidence exist for adherence to phosphate binder treatment?

Non-adherence is associated with poor control of phosphorus levels

A number of studies have examined the association between adherence to phosphate binders and serum phosphorus levels. From the recent literature:

  • Arenas et al. found that haemodialysis patients who were non-adherent to phosphate binders were significantly more likely to have high phosphorus than adherent patients. Non-adherence to phosphate binders was greater than for hypotensive agents, suggesting dialysis patients may have increased difficulty following binder regimens.[2]
  • A study of 76 peritoneal dialysis patients found adherence to phosphate binders was greatest in patients with low phosphorus levels. Multivariate analysis showed adherence was the only significant contributor to high serum phosphorus levels.[3]
  • In an analysis of 8,616 patients, lower adherence was associated with higher mean phosphorus levels and a lower percentage of patients with serum phosphorus ≤5.5 mg/dL.[4]
  • At ASN Kidney Week 2012, Tentori et al. presented an analysis of the DOPPS registry showing non-adherence to phosphate binders was associated with high phosphorus and PTH levels.

Studies such as these suggest that improved adherence may lead to a greater control of serum phosphorus, and a reduced risk of hyperphosphatemia. Given the well-documented links between high serum phosphorus levels and increased mortality in dialysis patients,[5] it seems likely that improving adherence to phosphate binders will have a positive effect on hard outcomes, similar to that seen from improved adherence in other diseases.

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Improving adherence may also deliver financial benefits

Poor adherence could also be leading to over-prescription of phosphate binders and a higher pill burden, as physicians escalate their attempts to control high phosphorus levels.[6] This over-prescription also has the potential to increase medication cost. A recent review focusing on the cost of adherence in multiple disease areas concluded that non-adherence is a significant contributor to avoidable healthcare costs in the US, and improving adherence could save “billions of dollars” per year.[7]

But how to improve adherence?

Evidence suggests that improved adherence to phosphate binders could improve outcomes and potentially lower medication costs. But how can clinicians improve adherence? The starting point for this analysis needs to be an understanding of why patients are not adhering to phosphate binders, and this will be the focus of our next few articles on COMPACT Renal.

See also the previous Adherence articles:
March 24th, 2014; Adherence Part 1 – The challenge of non-adherence in hyperphosphatemia

References

1. Simpson SH, Eurich DT, Majumdar SR, et al. A meta-analysis of the association between adherence to drug therapy and mortality. BMJ. 2006;333(7557):15. doi:10.1136/bmj.38875.675486.55.

2. Arenas MD, Malek T, Gil MT, Moledous A, Alvarez-Ude F, Reig-Ferrer A. Challenge of phosphorus control in hemodialysis patients: a problem of adherence? J Nephrol. 2010;23(5):525-534.

3. Hung K-Y, Liao S-C, Chen T-H, Chao M-C, Chen J-B. Adherence to phosphate binder therapy is the primary determinant of hyperphosphatemia incidence in patients receiving peritoneal dialysis. Ther Apher Dial Off Peer-Rev J Int Soc Apher Jpn Soc Apher Jpn Soc Dial Ther. 2013;17(1):72-77. doi:10.1111/j.1744-9987.2012.01098.x.

4. Wang S, Alfieri T, Ramakrishnan K, Braunhofer P, Newsome BA. Serum phosphorus levels and pill burden are inversely associated with adherence in patients on hemodialysis. Nephrol Dial Transplant Off Publ Eur Dial Transpl Assoc – Eur Ren Assoc. 2013. doi:10.1093/ndt/gft280.

5. Block GA, Klassen PS, Lazarus JM, Ofsthun N, Lowrie EG, Chertow GM. Mineral metabolism, mortality, and morbidity in maintenance hemodialysis. J Am Soc Nephrol JASN. 2004;15(8):2208-2218. doi:10.1097/01.ASN.0000133041.27682.A2.

6. Chiu Y-W, Teitelbaum I, Misra M, Leon EM de, Adzize T, Mehrotra R. Pill Burden, Adherence, Hyperphosphatemia, and Quality of Life in Maintenance Dialysis Patients. Clin J Am Soc Nephrol. 2009. doi:10.2215/CJN.00290109.

7. Iuga AO, McGuire MJ. Adherence and health care costs. Risk Manag Healthc Policy. 2014;7:35-44. doi:10.2147/RMHP.S19801.

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