This article previously appeared in the Fall Newsletter of the Canadian Association of Nephrology Dietitians (CAND). I write a short section called Spotlight on Science. If you are dietitian working in Kidney Care and not a member of CAND, check it out. CAND hosts awesome education events and provides an awesome connection to dietitians across Canada.
In May’s Journal of Renal Nutrition, the Academy of Nutrition and Dietetics reported on their “Assessing Uptake and Impact of Guidelines for Clinical Practice in Renal Nutrition (AUGmeNt)” study. The study was investigating whether dietitians are using the 2020 KDOQI Clinical Practice Guidelines for Nutrition in CKD recommended target for serum phosphorus levels.
What Do the 2020 KDOQI Guidelines Recommend?
The 2020 KDOQI Clinical Practice Guidelines for Nutrition in CKD recommend adjusting dietary phosphorus intake to maintain serum phosphate levels within the normal range, as per the local laboratory’s reference range. This is a change from the 2003 KDOQI guidelines, which had recommended a specific range of 1.13–1.78 mmol/L. However, as Vergili et al point out, since 2003, both the 2009 and 2017 KDIGO guidelines have no longer recommended allowing a higher phosphorus target and instead recommended using the local lab’s normal reference range. This means that the recommendation to allow higher phosphorus values is now 21 years old, and for the past 15 years tighter targets have been recommended.
Do Dietitians Typically Aim for Tighter Targets?
In this study, the authors audits the chart notes of dietitians working for two large national dialysis chains. Specifically, chart notes were reviewed to examine how dietitians documented phosphorus targets for their patients. Most dietitians noted that values between 0.81–0.97 mmol/L were too low, while values between 1.45–1.78 mmol/L were considered at target. This suggests that many dietitians are using a different reference range than what is recommended in the newest clinical practice guidelines.
Why Are Dietitians Using a Different Range?
The authors provided several potential reasons why dietitians might not be using the most up-to-date target ranges, including:
- Patient health factors: Malnourishment or limited life expectancy.
- Patient resources: Food insecurity, or lack of time, skills, or resources for cooking, leading to heavier reliance on phosphate-laden processed foods.
- Previous serum targets: For patients not at goal, it may be too difficult to achieve the target.
- Dietitian resources: Lack of time, resources, or training.
- Lack of confidence in the guidelines: Due to the absence of randomized controlled trials supporting the reduction of phosphorus to the normal lab reference range.
- System-level barriers: What the dialysis facility targets, or the lack of information about phosphorus in foods due to labeling laws.
What Should Be Done About This?
The final section of the paper presents a Call to Action at the clinician, institution, and government levels. At the clinician level, the authors recommend regular self-evaluation to ensure they are staying current in their practice. At the institutional level, efforts should be made to ensure clinic targets and policy documents reflect the most up-to-date guidelines. Finally, for the food industry and government, there is a push for greater transparency regarding the phosphorus content of foods.
My Takeaways
This article has made me reconsider the phosphate levels I target for my patients and reflect on why I choose the targets I do. For me, one of the most challenging pieces I find about this guideline is the acknowledged lack of evidence that lower serum phosphate targets through dietary restrictions and phosphate binders is associated with better outcomes for our patients. Highlighting how important, studies like the PHOSPHATE trial (which many of the renal dietitians across Canada are participating in! Hooray!) will be for helping inform practice.
Want to weigh in?
This article has made me curious to know what target dietitians in Canada are using. If you are a dietitian in Canada and want to participate – click this link or scan the QR code to answer a few questions about the phosphorus targets you are using in your practice. In the next CAND newsletter and on my blog I will share the results.
