Emergency referral lowers hyperkalemia deaths

Emergency department assessment within 24 hours was associated with lower short-term death after severe outpatient hyperkalemia.
*Retrospective population-based cohort study; Level 2b (OCEBM).

Citation

Chiu M, Nash DM, Smith G, et al. Emergency department referral and short-term death after outpatient hyperkalemia: a population-based study. CMAJ. 2026;198:E1176-E1185. doi:10.1503/cmaj.252008

Background

Severe high blood potassium can trigger fatal heart rhythm problems, but outpatient decisions are difficult when patients feel well or access is limited. This study examined whether emergency department evaluation after a severe outpatient result was linked to survival.

Patients

Adults in Ontario, Canada, with a nonhemolyzed outpatient potassium level greater than 6.2 mmol/L from 2007 to 2021. Exclusions included chronic dialysis, hospital-based testing, delayed reporting, death on report day, and missing recent creatinine.

Intervention

Emergency department visit within 24 hours of the potassium report.

Control

No emergency department visit within 24 hours, propensity matched 1:1.

Outcome

Death from any cause at 1, 3, and 7 days; cardiovascular death and new potassium binder prescriptions were secondary outcomes.

Follow-up Period

1, 3, and 7 days.

Results

Outcome Emergency department No emergency department Effect
Death at 1 day (primary) 20/6557 (0.3%) 51/6557 (0.8%) RR 0.39 (95% CI 0.24 to 0.65); RD −0.5% (95% CI −0.7% to −0.2%); NNT 200
Death at 3 days (primary) 40/6557 (0.6%) 86/6557 (1.3%) RR 0.47 (95% CI 0.32 to 0.67); RD −0.7% (95% CI −1.0% to −0.4%); NNT 143
Death at 7 days (primary) 85/6557 (1.3%) 124/6557 (1.9%) RR 0.69 (95% CI 0.52 to 0.90); RD −0.6% (95% CI −1.0% to −0.2%); NNT 167

RR = risk ratio; CI = confidence interval; RD = risk difference; NNT = number needed to treat.

Results used propensity-matched observational data. Benefit was greatest with potassium above 6.6 mmol/L or severely reduced kidney function. The control was not an active treatment strategy.

Limitations

Observational design cannot prove causation. Unmeasured differences, false high potassium results, outpatient management steps, and reasons for attending or avoiding the emergency department were not fully captured.

Funding

Academic/public funding; no funder role reported.

Clinical Application

Urgently refer severe outpatient potassium >6.2 mmol/L, especially >6.6 or advanced kidney disease; do not generalize to mild hyperkalemia.