MO517EFFECT MODIFIERS OF SERUM POTASSIUM AND MORTALITY IN THE IRISH HEALTH SYSTEM: THE NATIONAL KIDNEY DISEASE SURVEILLANCE SYSTEM (NKDSS). (29th May 2021)

• Record Type: Journal Article
• Authors: Browne, Leonard; Stack, Austin
• Is Part Of: Nephrology dialysis transplantation. Volume 36(2021)Supplement 1
• Publication Date: 2021-05-29
• Subjects: Nephrology -- Periodicals; Hemodialysis -- Periodicals; Kidneys -- Transplantation -- Periodicals; Hemodialysis; Kidneys -- Transplantation; Nephrology; Periodicals; 616.61
• DOI: 10.1093/ndt/gfab087.0037
• Languages: English
• ISSNs: 0931-0509

Abstract

Abstract: Background and Aims: Serum potassium (K+) exhibits a u-shaped association with mortality but uncertainty exists regarding optimal thresholds for survival and influencing factors. We examined the impact of serum K* on mortality in the Irish Health System with particular focus on kidney function and location of medical supervision. Method: We utilised data from the Irish Kidney Disease Surveillance System (NKSS) to explore the association of serum K+ and mortality in a longitudinal cohort study. We identified all adult individuals (age > 18 years) who accessed health care from 2007 and 2012 in a regional health system with complete data on serum K+, associated laboratory indicators and vital status up to 31st December 2013 (n = 32, 643). We randomly selected a single K+ measurement per patient with date of measurement as index date. Chronic kidney disease was defined as eGFR <60ml/min/1.73m² vs greater recorded at index date. Location of medical supervision was recorded as emergency room, inpatient location; outpatient clinic, and general practice location. The association of serum K+ was explored in categories and as a continuous variable in restricted cubic splines with mortality. Multivariable Cox regression determined hazard ratios and 95% confidence intervals with adjustment for baseline health indicators. Results: Mean age was 57.1 years, 5, 056 died (15.4%) with a median follow-up of 5.1 years. With adjustment, for age, sex, baseline health status, and location of medical supervision, the pattern of mortality was non-linear and u-shaped with greatest risks for patients with extreme values. Modelled as a continuous variable, the serum K +thresholds for optimal survival were from 4.1 to 5.2 mmol/L. Compared to patients without baseline CKD, the risks were attenuated for patients with CKD (p-value interaction 0.012). The associated risk thresholds were wider for CKD patients with significant increased risk above 5.8 mmol/L whereas, for those without CKD, serum K +thresholds for optimal survival were between 4.2-5.4 mmol/L. Similarly, mortality patterns were greatly attenuated for patients who were managed in the outpatient and general practice locations (p-value interaction <0.001) than the emergency room or inpatient settings (Figure 1 ). Conclusion: Risk thresholds for optimal survival for serum K+ vary according to CKD and location of medical supervision in real-world clinical cohorts. Better understanding of these thresholds and effect modifiers are essential for inform decision making and therapeutic interventions. Funding Source: Health Research Board (HRB-SDAP-2019-036), Midwest Research and Education Foundation (MKid), Vifor Pharma.