Value of free triiodothyronine levels in evaluating the severity and prognosis of elderly patients with coronavirus disease 2019 / 中华传染病杂志

ABSTRACT

Objective:To investigate the relationship between serum free triiodothyronine (FT 3) and the severity and prognosis of elderly patients with coronavirus disease 2019 (COVID-19). Methods:Clinical data of the elderly patients aged≥65 years old with COVID-19 who were admitted to the Ninth People′s Hospital of Wuxi from December 27, 2022 to January 18, 2023 were collected. The laboratory examinations of the non-severe and the severe/critical groups were compared. Patients were divided into group T1 (FT 3<2.51 pmol/L), group T2 (FT 3=2.51 to 2.95 pmol/L, ), and group T3 (FT 3>2.95 pmol/L) according to the FT 3 level. Independent sample t test was used for comparison between groups. Logistic regression analysis was performed to evaluate the risk factors for severe/critical disease, and to analyze the risk of severe/critical COVID-19 in elderly patients with different FT 3 levels. The receiver operator characteristic (ROC) curve was drawn to analyze the predictive value of FT 3 on the occurrence of severe/critical disease in patients. Kaplan-Meier survival curve and log-rank test were used to analyze the 30-day survival rate of elderly COVID-19 patients. Results:Among the 190 patients, the FT 3 level in the severe/critical group was (2.54±0.30) pmol/L, which was significantly lower than that in the non-severe group ((2.91±0.69) pmol/L), and the difference was statistically significant ( t=-3.42, P=0.001). Elevated serum FT 3 level was a protective factor for severe/critical disease in elderly COVID-19 patients (odds ratio ( OR)=0.139, 95% confidence interval ( CI) 0.034 to 0.577, P=0.007). There were 66 patients in the T1 group, 61 in the T2 group and 63 in the T3 group, respectively. After adjusted for sex, age, history of lung diseases, history of cardiac diseases, history of hypertension, history of diabetes mellitus, history of cerebral infarction, white blood cell count, lactate dehydrogenase, D-dimer, free thyroxine and thyrotropin, the risk of developing severe/critical disease in group T1 and group T2 were 10.982 folds and 3.695 folds of that in group T3, respectively (both P<0.05). The area under ROC curve of FT 3 of predicting severe/critical COVID-19 in the elderly patients was 0.731. The sensitivity and specificity were 0.733 and 0.659, respectively. The cut-off value was 2.53 pmol/L. The 30-day survival rate in patients with FT 3<2.53 pmol/L was significantly lower than that in patients with FT 3≥2.53 pmol/L ( χ2=13.49, P<0.001). Conclusions:The elevated level of FT 3 is a protective factor for progression to severe/critical disease in elderly patients with COVID-19. The evaluation of serum FT 3 could predict the severity and prognosis of elderly COVID-19 patients.