Roetker NS, Peng Y, Ashfaq A, Gilbertson DT, Wetmore JB: Adherence to Kidney Disease: Improving Global Outcomes Mineral and Bone Guidelines for Monitoring Biochemical Parameters. Am J Nephrol 2019;49:225–232
In 2018, KDIGO updated its clinical practice guidelines for the diagnosis, evaluation, prevention, and treatment of chronic kidney disease–mineral and bone disorders (CKD–MBD). Recommendations and suggestions for monitoring the biochemical disturbances that characterize CKD-MBD were explicitly stated, although the evidence that universal adoption of these guidelines would directly lead to improved patient-centered outcomes was weak or entirely lacking. Nevertheless, these guidelines acquired a “standard-of-care” status in the nephrology community. Compliance to these guidelines has been disappointingly low in small cohort studies.
Using a Medicare administrative data base consisting of claims for Parts A, B and D coverage for 2007–2015 (a period preceding the latest KDIGO guidelines), Roetker and co-workers analyzed the CKD-MBD laboratory testing of iPTH, calcium, phosphorus, alkaline phosphatase, and 25–OH vitamin D in 799,300 Medicare enrollees with CKD, based on International Classification of Diseases (ICD) diagnosis (80 % with stage 3, 17 % with stage 4, and 3 % with stage 5 [non-dialysis] CKD). Approximately ½ of the subjects had diabetes, 90 % had hypertension, and the mean ages were 74–78 years.
Less than ½ of the subjects received any testing for iPTH or 25-OH vitamin D. Testing that was included in comprehensive biochemical profiling (calcium alkaline phosphatase) were performed much more frequently, averaging 88 – 95 %. Older age was associated with less testing and prior nephrology care was associated with increased testing for iPTH and phosphorus levels. The presence of co-morbidity had no consistent relationship with testing character or frequency, with a few exceptions. Given these findings from a very large cohort of Medicare enrollees, it seems likely that secondary hyperparathyroidism and hyperphosphatemia are “underdiagnosed” in CKD, at least in this cohort.
Whether this “deficiency” is contributing to avoidable mortality or morbidity remains very uncertain and cannot be studied in an analysis of this design. A major limitation of the Roetker et al. study is that it can only examine the frequency of testing, not whether abnormal test findings leading to an action of some sort were found. This study does highlight a low compliance to KDIGO CKD-MBD guidelines in aggregate among older adults with “CKD”. This raises questions regarding the accuracy of CKD diagnosis in the older individual (since the glomerular filtration rate [GFR] based diagnostic criteria are not age-adapted). It also poses issues concerning the presence of skepticism or nihilism in the application of guidelines to testing strategies employed by primary care physicians. It is also possible that some degree of lack of awareness of the details of current guidelines contributed to the disturbing findings. Even if an association between compliance to guideline suggestions/recommendations and better patient outcomes existed, it might simply represent the effect of compliance itself on outcomes rather than to any salubrious impact of the guidelines themselves. The gap between CKD-MBD guidelines and direct benefits to patients is large and deserving of much more study, in my opinion.