Management of mineral bone disorders (MBD) in patients with non-dialysis chronic kidney disease (CKD) varies internationally, particularly with respect to target levels of biomarkers and use of prescription medication, according to new study findings.

A team led by Ziad A. Massye, MD, PhD, of Ambroise Paré University Hospital in France, analyzed data from 7658 patients (estimated glomerular filtration rate [eGFR] less than 60 mL/min/1.73m2) participating in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) in Brazil, France, Germany, and the United States. According to results published in Bone, more than two-thirds of patients had MBD markers measured at timely intervals in keeping with guidelines. As eGFR decreased, serum phosphate (P) and intact parathyroid hormone (iPTH) levels increased — gradually until 20 mL/min/1.73 m2, then sharply. Concurrently, serum calcium decreased. Levels of 25-hydroxyvitamin D (25-D) did not change predictably.

Target ranges of MBD markers as well as prescription patterns varied among countries. Nephrologists surveyed in CKDopps reported various upper limits for “target range” P and iPTH. Phosphate binder use ranged from 14% to 43% among patients with serum P exceeding 5.5 mg/dL. Use of active vitamin D (calcitriol and related analogs) spanned from 12% to 51%, and use of any (active or nutritional) vitamin D 60% to 87% among patients with iPTH exceeding 300 pg/mL.

The 2017 Kidney Disease Improving Global Outcomes (KDIGO) CKD-MBD guidelines encouraged normalizing laboratory markers but lacked specific target recommendations. “Clinical uncertainty about optimal and attainable lab targets is evident in the variation in the target lab values for P and PTH selected by nephrologists participating in CKDopps,” according to Dr Massye’s team.

“Although monitoring of CKD-MBD laboratory markers by nephrologists in CKDopps countries is consistent with guidelines, target levels vary notably and prescription of medications to treat abnormalities in these laboratory markers is generally low in these cross-sectional analyses,” the investigators concluded.

Nephrologists may be avoiding prescribing phosphate binders to non-dialysis CKD patients because of the lack of reliable trial data and safety concerns such as vascular calcification, according to the authors. Waiting to treat MBD until advanced CKD is always an option, but the effect of waiting on longer-term complications requires study.

“Early intervention and preventive efforts, perhaps begun while laboratory markers are within target limits, may result in better overall and longer-term management,” Dr Massye’s team stated.

This study was funded by Vifor Fresenius Medical Care Renal Pharma.

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Reference

Liabeuf S, McCullough K, Young EW, et al. International variation in the management of mineral bone disorder in patients with chronic kidney disease: Results from CKDopps [published online September 4, 2019]. Bone. doi:10.1016/j.bone.2019.115058