Association of Pre-ESRD Serum Calcium With Post-ESRD Mortality Among Incident ESRD Patients: A Cohort Study

Abstract

Albumin-corrected serum calcium (cSCa) decline at late stages of chronic kidney disease and rise after dialysis initiation. Although hypercalcemia is associated with higher mortality in end-stage renal disease (ESRD), there are scarce data on the impact of pre-ESRD cSCa on post-ESRD mortality. Therefore, we used a large national cohort of 21,826 US veterans who transitioned to dialysis in all US Department of Veterans Affairs health care facilities over 2009 to 2014 to examine the associations with all-cause and cause-specific post-ESRD mortality of (1) cSCa concentrations averaged over the last 6 months and (2) its rate of decline during the last 12 months before dialysis initiation. Mean concentrations and median rate of decline of cSCa were 9.3 ± 0.7 mg/dL and -0.15 (interquartile range -0.39 to 0.07) mg/dL/year, respectively. A total of 9596 patients died during the follow-up period (mean 1.9 years; total 41,541 patient-years) with an incidence rate of 23.1 per 100 patient-years. There was an independent linear association between higher cSCa with higher mortality (p < 0.001). The mortality risk associated with cSCa ≥9.0 mg/dL was attenuated among active vitamin D users (p < 0.001). Patients with faster decline in cSCa showed lower mortality irrespective of baseline cSCa concentrations. These cSCa-mortality associations were stronger for noncardiovascular versus cardiovascular death. In conclusion, lower pre-ESRD cSCa and faster decline in cSCa were consistently and linearly associated with better post-ESRD survival among US veterans, especially for noncardiovascular death. Further studies are needed to determine if correcting hypocalcemia is beneficial or harmful and which intervention is preferred when indicated among patients transitioning to ESRD. © 2018 American Society for Bone and Mineral Research.

Hidden Hypocalcemia as a Risk Factor for Cardiovascular Events and All-Cause Mortality among Patients Undergoing Incident Hemodialysis

“…Prior studies reported the association between higher corrected calcium and poor prognosis 8,9 . This association might be partly explained by overestimation of calcium status among patients with hypoalbuminemia, who are at high risk for mortality 26 .…”

“…The reason for this discrepancy might reside in the www.nature.com/scientificreports www.nature.com/scientificreports/ different timings of blood sampling; calcium levels were measured just before the first dialysis in this study, while they were measured during the first 91 days of dialysis in the previous study. Corrected calcium levels increased after dialysis initiation among patients with low corrected calcium levels 8 , likely because of a positive calcium balance during dialysis 20 , active vitamin D treatment, and/or calcium-based phosphate binders. Despite the discrepancy, approximately 60% of the patients with true hypocalcemia were incorrectly categorized as normocalcemia using corrected calcium both in our cohort and in the previous study.…”

“…A large cohort of maintenance hemodialysis patients showed a U-shaped association between corrected calcium and mortality 7 . Two other studies reported that higher calcium levels were associated with worse prognosis among patients undergoing incident dialysis 8,9 . In a large cohort of patients with estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m 2 , a U-shaped association between calcium and mortality was observed 10 .…”

Dialysis Provider and Outcomes among United States Veterans Who Transition to Dialysis

“…The Transition of Care in CKD study cohort has been previously described (11)(12)(13)(14)(15)(16). Briefly, a retrospective cohort study was performed examining United States veterans with incident ESKD who transitioned to kidney replacement therapy from October 1, 2007 to March 30, 2014.…”

Association of Pre-End-Stage Renal Disease Hemoglobin with Early Dialysis Outcomes

“…The analytical cohort was derived from the United States Renal Data System (USRDS) Special Study Center Transition of Care in CKD, which aimed to investigate incident ESRD US veterans who transitioned to ESRD between October 1, 2007 and March 30, 2014 [18-23]. Of the original population of 85,505 veterans derived from USRDS records, we excluded patients without data on follow-up ( n = 1,958) and with missing date of birth ( n = 3).…”