A lower threshold for referral to the emergency department for outpatient hyperkalemia may reduce mortality

1. Patients with an emergency department encounter within 24 hours of severe outpatient hyperkalemia had lower rates of immediate and short-term death compared to patients who did not have an emergency department encounter. 

Evidence Rating Level: 2 (Good)

Study Rundown: Hyperkalemia, or an elevated blood potassium level, may trigger fatal arrhythmias. Most treatments for immediate management of hyperkalemia can only be administered in a hospital setting, often in the emergency department. Despite guideline recommendations for prompt referral to the emergency department, there is limited evidence to guide clinicians on whether and when patients should be referred to the emergency department. There is a need to better understand whether presentation to the emergency department reduces the mortality risk associated with hyperkalemia. This study thus investigated whether presentation to the emergency department within 24 hours of a severe outpatient hyperkalemia result was associated with lower rates of immediate and short-term all-cause death.

This retrospective population-based cohort study included adults aged ≥18 years with an outpatient potassium result greater than 6.2 mmol/L. An emergency department encounter was defined as a visit within 24 hours of a severe outpatient hyperkalemia result. The primary outcome was all-cause death within 1, 3, and 7 days after the emergency department encounter. In total, 57,607 patients were included in the study. After propensity matching, 6557 had an emergency department encounter, and 6557 did not. A total of 209 deaths (1.6%) occurred within 7 days. The risk of death was 61% lower among patients with an emergency department encounter at 1 day, 53% lower at 3 days, and 31% lower at 7 days.

Overall, this study found that patients who presented to the emergency department within 24 hours of severe outpatient hyperkalemia had lower rates of immediate and short-term death compared to patients who did not present to the emergency department.

Click to read the study in CMAJ 

Relevant reading: Hyperkalemia in the emergency department: Etiology, symptoms and outcome of a life threatening electrolyte disorder

In-Depth [retrospective cohort study]:

This study, conducted in Ontario, Canada, included adults aged ≥18 years with a non-hemolyzed outpatient potassium result >6.2 mmol/L from January 1, 2007, to December 24, 2021. An emergency department encounter was defined as a visit within 24 hours of a severe outpatient hyperkalemia result. Patients who had an emergency department encounter were propensity-matched (1:1) to patients who did not. The primary outcome was all-cause death within 1, 3, and 7 days after the emergency department encounter. In total, 57,607 patients were included in the study (mean [SD] age = 64.9 [18.2], female [%] = 27,503 [47.7%]). After propensity matching, 6557 presented to the emergency department within 24 hours of the potassium report, and 6557 patients did not. A total of 209 deaths (1.6%) occurred within 7 days. The risk of death was lower among patients with an emergency department encounter at 1 day (risk ratio [RR] 0.39, 95% confidence interval [CI] 0.24 to 0.65), 3 days (RR 0.47, 95% CI 0.32 to 0.67), and 7 days (RR 0.69, 95% CI 0.52 to 0.90). The risk difference was −0.5% (95% CI −0.7% to −0.2%) at 1 day, −0.7% (95% CI −1.0% to −0.4%) at 3 days, and −0.6% (95% CI −1.0% to −0.2%) at 7 days. Overall, this study found that patients who presented to the emergency department within 24 hours of severe outpatient hyperkalemia had lower rates of immediate and short-term death compared to patients who did not present to the emergency department. These findings highlight the importance of urgent emergency department referrals for severe outpatient hyperkalemia and the need for standardized management guidelines for clinicians. Some strengths of this study include a large and diverse study cohort allowing for generalizability, and propensity matching that accounted for important confounders. Some limitations of this study include inability to identify factitious hyperkalemia beyond hemolysis, presence of unmeasured confounding and confounding by indication, and inability to determine if cause of death was hyperkalemia or another condition. Future studies are needed to confirm study findings and address these limitations. 

Image: PD

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