Diagnostic accuracy of emergency department ECGs in hyperkalemia detection: A cross-sectional study

OBJECTIVE: To assess the diagnostic accuracy of ECG readings in detecting hyperkalemia and predicting outcome in the ED.

METHODS: A retrospective cross-sectional analysis was conducted on ED patients, including patients with confirmed hyperkalemia (≥ 5 mmol/l) and a normokalemic control group. The predictive value of ECG readings for the detection of hyperkalemia was studied. For this purpose, the subjective probability of hyperkalemia was rated from 0-100 (Hyperkalemia Probability Scoring) by two attending acute care physicians. Logistic regression and ROC analysis were used to assess predictive power and sensitivity/specificity of Hyperkalemia Probability Scorings. Prediction of 7-day adverse outcomes (ICU admission, hemodialysis, in-hospital mortality) based on Hyperkalemia Probability Scorings was analyzed.

RESULTS: We studied 1608 patients, thereof 805 served as normokalemic control patients. Sensitivity and specificity of ECG readings for hyperkalemia detection were 0.47 and 0.76 for cardiologist 1, and 0.39 and 0.81 for cardiologist 2. The AUC was 0.63 (95 % CI 0.60-0.65) and 0.61 (95 % CI 0.59-0.63) for the respective cardiologists. With a Hyperkalemia Probability Scoring of 100 compared to 0, the Odds Ratios (ORs) of diagnosing hyperkalemia were 8.2 (95 % CI 5.3-12.6) and 9.1 (95 % CI 5.8-14.7), while the ORs for 7-day adverse outcomes were 2.14 (95 % CI 1.34-3.38) and 2.22 (95 % CI 1.39-3.49) respectively.

CONCLUSION: The ECG is not an accurate tool for ruling-in or ruling-out hyperkalemia in ED patients. Higher Hyperkalemia Probability Scorings are associated with 7-day adverse outcomes.