Potassium Iodide Use and Patient Outcomes for Thyroid Storm: An Observational Study

Context Iodine, combined with antithyroid drugs, is recommended as an initial pharmacologic treatment for thyroid storm according to some clinical guidelines. However, the clinical efficacy of iodine in managing thyroid storm remains unexplored.Objective This study aimed to determine whether early potassium iodide (KI) use is associated with mortality in patients hospitalized for thyroid storm.Methods Using the Japanese Diagnosis Procedure Combination database, we identified patients hospitalized with thyroid storm between July 2010 and March 2022. We compared in-hospital mortality, length of stay, and total hospitalization costs between patients who received KI within 2 days of admission (KI group) vs those who did not (non-KI group). Prespecified subgroup analyses were performed based on the presence of the diagnosis of Graves' disease.Results Among 3188 eligible patients, 2350 received KI within 2 days of admission. The crude in-hospital mortality was 6.1% (143/2350) in the KI group and 7.8% (65/838) in the non-KI group. After adjusting for potential confounders, KI use was not significantly associated with in-hospital mortality (odds ratio [OR] for KI use, 0.91; 95% CI, 0.62-1.34). In patients with the diagnosis of Graves' disease, in-hospital mortality was lower in the KI group than in the non-KI group (OR, 0.46; 95% CI, 0.25-0.88). No significant difference in in-hospital mortality was observed in patients without the diagnosis of Graves' disease (OR, 1.11; 95% CI, 0.67-1.85). Length of stay was shorter (subdistribution hazard ratio, 1.15; 95% CI, 1.05-1.27), and total hospitalization costs were lower (OR, 0.92; 95% CI, 0.85-1.00) in the KI group compared with the non-KI group.Conclusion Our findings suggest that KI may reduce in-hospital mortality among patients hospitalized for thyroid storm with Graves' disease.