Predictors of Hyperkalemia among Patients on Maintenance Hemodialysis Transported to the Emergency Department by Ambulance

Background Hyperkalemia is common among patients on maintenance hemodialysis (HD) and is associatedwith mortality. We hypothesized that clinical characteristics available at time of paramedic assessment beforeemergency department (ED) ambulance transport (ambulance-ED) would associate with severe hyperkalemia(K >= 6 mmol/L). Rapid identification of patients who are at risk for hyperkalemia and thereby hyperkalemia-associated complications may allow paramedics to intervene in a timely fashion, including directing emergencytransport to dialysis-capable facilities. Methods Patients on maintenance HD from a single paramedic provider region, who had at least oneambulance-ED and subsequent ED potassium from 2014 to 2018, were examined using multivariable logisticregression to create risk prediction models inclusive of prehospital vital signs, days from last dialysis, and thepresence of prehospital electrocardiogram (ECG) features of hyperkalemia. We used bootstrapping withreplacement to validate each model internally, and performance was assessed by discrimination and calibration. Results Among 704 ambulance-ED visits, severe hyperkalemia occurred in 75 (11%); 26 patients with EDhyperkalemia did not have a prehospital ECG. Younger age at transport, longer HD vintage, more days from lasthemodialysis session (OR549.84; 95% CI, 7.72 to 321.77 for >= 3 days versus HD the same day [before] EDtransport), and prehospital ECG changes (OR56.64; 95% CI, 2.31 to 19.12) were independently associated withsevere ED hyperkalemia. A model incorporating these factors had good discrimination (c-statistic 0.82; 95% CI,0.76 to 0.89) and, using a cutoff of 25% probability, correctly classified patients 89% of the time. Conclusions Characteristics available at the time of ambulance-ED were associated with severe EDhyperkalemia. An awareness of these associations may allow health care providers to define novel care pathwaysto ensure timely diagnosis and management of hyperkalemia.