Monitoring, Control, and Clinical Outcomes Associated With Chronic Kidney Disease-Mineral Bone Disorder: A Population-Based Cohort Study in Ontario, Canada

Abstract

Rationale & Objective

Chronic kidney disease-mineral and bone disorder (CKD-MBD) affects bone and cardiovascular health. We examined the monitoring, control, and outcomes associated with CKD-MBD.

Study Design

Observational cohort study using ICES administrative data.

Setting& Participants

Adults aged 40 years and older from Ontario, Canada, with at least 2 outpatient estimated glomerular filtration rate values or receiving dialysis between January 2017 and March 2020.

Exposure

CKD stage based on the estimated glomerular filtration rate.

Outcomes

Albumin-corrected serum calcium, phosphate, alkaline phosphatase, parathyroid hormone, and 25 hydroxyvitamin D testing and control at 365 days, and the percentage of patients monitored and controlled per guidelines. We also examined the association between laboratory values, fragility fracture, and major adverse cardiovascular events (MACE) in CKD stage 4, 5 and dialysis.

Analytical Approach

Descriptive statistics were used for primary and secondary outcomes. For exploratory outcomes, we examined the cumulative incidence and incidence rate of fragility fracture and MACE based on laboratory values, and adjusted analyses using multivariable Cox proportional hazards models.

Results

There were 2,580,781 people included, of whom, 303,884 had CKD (stage 3A or higher). Monitoring and control of CKD-MBD was suboptimal across the CKD spectrum. Even in maintenance dialysis, the proportion who met laboratory monitoring targets was low (5.1% had all tests measured over 365 days). The most commonly controlled laboratory value was alkaline phosphatase (55.6% were at target across the CKD spectrum). In exploratory analysis, a small protective effect of a higher calcium and phosphate level on fragility fracture was observed, with a parathyroid hormone level of 20-80 pmol/L appearing optimal for bone health in dialysis. There appeared to be a small statistically significant association between higher levels of alkaline phosphatase and phosphate with MACE in dialysis.

Limitations

Results are only generalizable to adults with laboratory tests reported within the Ontario Laboratory Information System. Exploratory analyses were limited by events.

Conclusions

There are gaps in the monitoring and control of CKD-MBD in Ontario, even in groups in which evidence to support management is highest. Focused studies on whether the control of CKD-MBD improves patient-important outcomes remain important.

Plain-Language Summary

Calcium, phosphate, parathyroid hormone, and vitamin D are important for to kidney health. We examined how often these tests are being measured in people with kidney disease and how well they are being controlled in the real world. We found several gaps in the measurement and control of these laboratory tests - it does appear that having laboratory values in a good range is important for both bone and heart health based on our study. We hope that this study helps doctors and patients, and that it promotes more research in this theme.