Methimazole Effective Substitution for Propylthiouracil in Patients With Thyroid Storm

Outcomes of in-hospital death and discharge to hospice care did not significantly differ between patients with thyroid storm who received propylthiouracil vs methimazole.

Methimazole is an effective substitution for propylthiouracil as first-line treatment for patients with thyroid storm, according to study results published in JAMA Network Open.

The American Thyroid Association (ATA) recommends propylthiouracil over methimazole as first-line treatment for thyroid storm, though the difference in outcomes between each treatment is unclear.

Researchers compared outcomes of propylthiouracil with methimazole among a large cohort of adult patients with thyroid storm in the United States. The Premier Healthcare Database and diagnostic codes were utilized to capture data from patients who were admitted to the intensive care unit (ICU) with thyroid between January 2016 and December 2020. Patients included in the analysis received either propylthiouracil or methimazole on the first or second day of ICU admission. The primary composite outcome was the adjusted risk difference (aRD) of in-hospital death or discharge to hospice between the treatment groups, calculated via targeted maximum likelihood estimation.

Among 1383 patients included in the final analysis, 656 patients received propylthiouracil and 727 received methimazole. Of patients in the propylthiouracil and methimazole groups, the mean (SD) ages were 45 (16) and 45 (16) years, 72.1% and 75.5% were women, and 54.0% and 51.9% were White, respectively.

The researchers found that in-hospital death or discharge to hospice care occurred among 7.4% (95% CI, 6.0%-8.8%) of the total patient population. Stratified by treatment group, in-hospital death or discharge to hospice care occurred among 8.5% (95% CI, 6.4%-10.7%) of patients in the propylthiouracil group and 6.3% (95% CI, 4.6%-8.1%) of those in the methimazole group (aRD, 0.6%; 95% CI, -1.8% to 3.0%; P =.64).

Given the findings of this study, as well as other studies, current ATA recommendations on the choice of thionamides may benefit from reevaluation.

No significant between-group differences were observed for outcomes of in-hospital death alone (aRD, 1.1%; 95% CI, -1.2% to 3.5%; P =.34) or discharge to hospice alone (aRD, -0.6%; 95% CI, -1.6% to 0.3%; P =.20).

There also were no significant between-group differences in organ support-free days (adjusted mean difference, [aMD], -0.2 days; 95% CI, -0.7 to 0.3 days; P =.40) and total cost of hospitalization (aMD, $1097; 95% CI, -$972 to $3166; P =.30).

A sensitivity analysis of 2845 patients using full optimal matching showed no significant between-group differences in the occurrence of in-hospital death or discharge to hospice care (aRD, -0.6%; 95% CI, -3.7% to 2.4%; P =.68)

Study limitations include the lack of standard diagnostic criteria for thyroid storm, as well as missing information on medications taken prior to hospitalization and the specific timing of treatment initiation.

“These results suggest that propylthiouracil and methimazole can be used interchangeably in the management of thyroid storm,” the researchers noted. “Given the findings of this study, as well as other studies, current ATA recommendations on the choice of thionamides may benefit from reevaluation,” they concluded.

References:

Lee SY, Modzelewski KL, Law AC, et al. Comparison of propylthiouracil vs methimazole for thyroid storm in critically ill patientsJAMA Netw Open. 2023;6(4):e238655 .doi:10.1001/jamanetworkopen.2023.8655