Date of publication: March 24, 2014

News & Views

Adherence (Part 1) – The challenge of non-adherence in hyperphosphatemia

Phosphate binders have been shown to be effective in regulating phosphorus levels [1,2] and yet according to a recent large observational study, 50% of patients have serum phosphorous concentrations outside the target range. Clinical studies have demonstrated the efficacy of phosphate binders in controlling serum phosphorus and observational studies confirm their widespread use,[1] so to what extent is the difficult of controlling phosphorus levels caused by non-adherence to binder regimens?[3]

Phosphate binders have shown to be effective at controlling phosphorus levels

Phosphate binders are widely used in dialysis patients to control phosphate levels and observational studies have shown their use to be associated with improved survival outcomes.

  • In a study of 6,797 dialysis patients Cannata-Andia et al. found that patients prescribed phosphate binders had 29% lower all-cause mortality risk and a 22% lower cardiovascular mortality risk.[1]
  • Treatment with phosphate binders was independently associated with decreased mortality in an observational study of 10,044 incident dialysis patients.[2]

Despite the widespread use of binders, phosphorus levels in general are poorly controlled, with 50% of patients in a recent study found to have poorly controlled phosphorus levels at baseline. One possible reason for this is the underestimation of the amount of highly absorbable, ‘hidden’ phosphorus in Western diets, which has been shown to be particularly high in processed foods.[4] Alongside this, there is also a growing body of evidence highlighting that many dialysis patients are not adhering to their binder medication.

Evidence suggests patient adherence to phosphate binders is poor

Non-adherence is a problem in many chronic diseases, but can be especially challenging for dialysis patients due to a complex treatment regimen involving both dietary restrictions and multiple medications. Numerous studies have shown that the prevalence of patient non-adherence to phosphate binder treatments is high:

  • A survey in 2010 found 76% of nephrologists and 63% of dialysis staff thought non-adherence was the main reason for poor control of phosphorus levels in patients.[5]
  • In a cross-sectional study, 502 haemodialysis patients responded to a questionnaire with approximately 70% stating they were non-adherent to phosphate binders.[6]
  • A  recent study of Spanish dialysis patients found that 60% were non-adherent to their phosphate binder treatment regimens.[7]
  • In another study by the same author, results found that in 165 dialysis patients, 40% were non-adherent to their treatments and 21% admitted non-adherence to phosphate binders.[8]
  • A systemic review of 34 studies found non-adherence rates averaged at 51% and ranged from 22% to 74%. The result of this review highlighted the variability in measures of adherence.[9]

These data suggest that non-adherence is an important issue in phosphate binder therapy and it is a logical step to suggest that improving these adherence rates could lead to better treatment outcomes for dialysis patients.

This is the first in a series of articles discussing adherence, outcomes & pill burden in hyperphosphatemia. In our next article we will look at associations between adherence and improved outcomes.

References

  1. Cannata-Andía JB, Fernández-Martín JL, Locatelli F, et al. Use of phosphate-binding agents is associated with a lower risk of mortality. Kidney Int. 2013;84(5):998-1008. doi:10.1038/ki.2013.185.
  2. Isakova T, Gutiérrez OM, Chang Y, et al. Phosphorus binders and survival on hemodialysis. J Am Soc Nephrol JASN. 2009;20(2):388-396. doi:10.1681/ASN.2008060609.
  3. Covic A, Rastogi A. Hyperphosphatemia in patients with ESRD: assessing the current evidence linking outcomes with treatment adherence. BMC Nephrol. 2013;14:153. doi:10.1186/1471-2369-14-153.
  4. Carrigan A, Klinger A, Choquette SS, et al. Contribution of Food Additives to Sodium and Phosphorus Content of Diets Rich in Processed Foods. J Ren Nutr. 2014;24(1):13-19.e1. doi:10.1053/j.jrn.2013.09.003.
  5. Toussaint ND, Pedagogos E, Beavis J, Becker GJ, Polkinghorne KR, Kerr PG. Improving CKD-MBD management in haemodialysis patients: barrier analysis for implementing better practice. Nephrol Dial Transplant. 2010:gfq602. doi:10.1093/ndt/gfq602.
  6. Martins MTS, Silva LF, Kraychete A, et al. Potentially modifiable factors associated with non-adherence to phosphate binder use in patients on hemodialysis. BMC Nephrol. 2013;14(1):208. doi:10.1186/1471-2369-14-208.
  7. Dolores Arenas M, Pérez-García R, Bennouna M, et al. Improvement of therapeutic compliance in haemodialysis patients with poor phosphorus control and adherence to treatment with binders: COMQUELFOS study. Nefrol Publ Of Soc Esp Nefrol. 2013;33(2):196-203. doi:10.3265/Nefrologia.pre2012.Oct.11726.
  8. 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.
  9. Karamanidou C, Clatworthy J, Weinman J, Horne R. A systematic review of the prevalence and determinants of nonadherence to phosphate binding medication in patients with end-stage renal disease. BMC Nephrol. 2008;9(1):2. doi:10.1186/1471-2369-9-2.

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