Time to euthyroidism and its predictors among thyrotoxicosis patients on antithyroid drugs at tertiary hospitals, Western Oromia, Ethiopia: a retrospective cohort study.

INTRODUCTION

Thyrotoxicosis is characterized by excessive action of thyroid hormones in tissues, leading to significant morbidity and mortality. Anti-thyroid drugs are the primary treatment for thyrotoxicosis; however, the time required to achieve euthyroid status varies among patients. The aim of this study was to determine the time to euthyroidism and its predictors among thyrotoxicosis patients on anti-thyroid drugs at tertiary hospitals in Nekemte city.

METHODS

A five-year hospital-based retrospective cohort study (from January 1, 2020, to December 31, 2024) was conducted among patients treated with anti-thyroid drugs at Wollega University and Nekemte Comprehensive Specialized Hospitals. Data were extracted using a checklist, entered into Epi Data 4.6, cleaned, exported, and analyzed in STATA 14.1. Descriptive statistics (mean, median, incidence, interquartile range) were used to summarize the data. A Kaplan-Meier curve was used to estimate survival probabilities and compare between groups. The log-rank test was utilized to assess the existence of differences in survival probability. Bi-variable Cox regression analysis (with P ≤ 0.25) was performed to identify candidate predictors. The proportional hazards assumption was assessed using a global test. Subsequently, in suba multivariable Cox regression analysis was conducted to determine the independent predictors of time to euthyroidism, with variables considered statistically significant at p-values < 0.05.

RESULTS

In this study, the median time to euthyroidism was 10.8 months. The incidence rate of achieving euthyroidism among thyrotoxicosis patients was 67.91 per 1000 person-months. The following factors were significantly associated with time to euthyroidism: Graves' disease (AHR = 2.50; 95% CI: 1.23-5.07), WHO goiter grade 3 (AHR = 1.98; 95% CI: 1.55-2.54), overt hyperthyroidism (AHR = 1.48; 95% CI: 1.04-2.10), congestive heart failure (AHR = 0.56; 95% CI: 0.35-0.91), and renal disease (AHR = 0.40; 95% CI: 0.21-0.79).

CONCLUSION

The time to euthyroidism in this study was comparatively long; however, the rate of normalization at the end of follow-up was relatively high. The study found that Graves' disease, overt hyperthyroidism, WHO grade 3 goiter, congestive heart failure, and renal disease were significant predictors of time to euthyroidism in patients treated with anti-thyroid drugs. These findings emphasize the importance of prioritizing the management of these factors to improve euthyroidism outcomes in thyrotoxicosis patients.