Rationale & Objective: Hyperkalemia is a common electrolyte abnormality of chronic kidney disease and heart failure associated with increased mortality and morbidity. We aimed to assess the long-term economic burden of hyperkalemia. Design: Observational cohort study using a Japanese nationwide hospital claims database (April 1, 2008, to September 30, 2018). Setting & Population:: Patients 18 years or older with at least 1 serum potassium value (N = 1,208,894). Exposures: Hyperkalemia defined with the presence of at least 2 serum potassium values ≥ 5.1 mmol/L. Outcome Measures: Direct health care costs and resource use in patients with hyperkalemia within and after 12 months from first hyperkalemia episodes. Analytical Approach: Health care costs and resource use were compared with propensity score–matched or nonmatched normokalemic controls. Multivariable regression analysis was performed to examine factors associated with health care costs. Results: 27,534 patients with hyperkalemia and 233,098 normokalemic controls were studied. Mean ± SD age was 73±13 years in patients with hyperkalemia; among them, 59% and 35% had chronic kidney disease and heart failure, respectively. In the propensity score–matched cohort (n = 5,859 in each group), average numbers of hospitalizations per patient per year in patients with hyperkalemia within and after 12 months were 1.2 and 1.6 times higher, respectively, compared with those in patients with normokalemia. The total cost per patient in patients with hyperkalemia was higher than for controls, with mean differences of $8,611 (95% CI, $8,046-$9,175) within 12 months and $5,150 (95% CI, $4,733-$5,566) after 12 months. The number of repeat hyperkalemic episodes was the factor with the strongest association with long-term health care costs, whereas severity of hyperkalemia was not associated. Limitations: This study used secondary data; therefore, residual confounders may not be fully excluded. Conclusions: Hyperkalemia was associated with significant long-term economic burden with frequent hospitalizations due to recurrent episodes, indicating the importance of hyperkalemia treatment for the sake of reducing health economic burdens and clinical complications.
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