Supplementary Material for: Adherence to Kidney Disease: Improving Global Outcomes Mineral and Bone Guidelines for Monitoring Biochemical Parameters

Background: Mineral and bone disorder (MBD) is common in patients with chronic kidney disease (CKD), and is associated with risk of fractures, cardiovascular disease, and death. Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend monitoring CKD-MBD biochemical markers, including parathyroid hormone (PTH), phosphorus, 25-hydroxyvitamin D (25D), calcium, and alkaline phosphatase (ALP), in patients with moderate-to-severe CKD. Methods: To determine guideline adherence, we used administrative claims records from the 20% sample of Medicare beneficiaries with Parts A, B, and D coverage, 2007 to 2015, and identified cohorts of patients with nondialysis stage 3, 4, or 5 CKD. Testing for biochemical markers during follow-up was defined based on laboratory procedure codes. Baseline factors associated with laboratory testing were determined using logistic regression. All analyses were performed separately by CKD stage. Results: A total of 640,946 stage 3, 136,278 stage 4, and 22,076 stage 5 CKD patients, 50.2–52.9% women, mean age 74.4–78.0 years, were followed for a mean of 2.5, 1.3, and 0.7 years respectively. The frequency of testing was low for PTH (35.2–48.2%), phosphorus (46.6–62.0%), and 25D (29.3–46.7%). Testing was somewhat higher for calcium (88.1–95.4%) and ALP (63.5–88.1%); most tests were features of larger panels (e.g., basic metabolic panel). Older age, most comorbid conditions, and lack of prior nephrology care were associated with lower likelihood of testing. Conclusions: In fee-for-service Medicare beneficiaries, laboratory testing for CKD-MBD biochemical markers appears to be suboptimal in relation to KDIGO guidelines. Competing priories, such as management of comorbid disease and preparation for renal replacement therapy, may distract from CKD-MBD monitoring.