Free Triiodothyronine and Free Triiodothyronine to Free Thyroxine Ratio Predict All-Cause Mortality in Patients with Diabetic Foot Ulcers

• Published in: Diabetes, metabolic syndrome and obesity Vol. 15; pp. 467 - 476
• Main Authors: Hong, Jing, Liu, Wen-Yue, Hu, Xiang, Chen, Wen-Wen, Jiang, Fei-Fei, Xu, Ze-Ru, Shen, Fei-Xia, Zhu, Hong
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2022; Dove; Dove Medical Press
• Subjects: Aged; Analysis; China; Diabetic foot; diabetic foot ulcer; Diabetics; ft3; ft3/ft4 ratio; Hospital patients; Medical research; Medicine, Experimental; Mortality; Original Research; Patient outcomes; Prognosis; Thyroxine; Type 2 diabetes; China; mortality; FT3/FT4 ratio; diabetic foot ulcer; FT3
• ISSN: 1178-7007; 1178-7007
• DOI: 10.2147/DMSO.S354754

Free triiodothyronine (FT3) and FT3/free thyroxine (FT4) ratio have been associated with mortality in various diseases. However, no study to date has identified a link between FT3, FT3/FT4 ratio and all-cause mortality in patients with diabetic foot ulcers (DFUs). This study aimed to investigate this relationship. This retrospective cohort study included 726 patients diagnosed with DFUs in a public hospital from January 2015 to October 2019. Patients were classified by the optimal cut-off values of the FT3 and FT3/FT4 ratio, respectively. The association of FT3 and FT3/FT4 ratio with all-cause mortality was evaluated in a multivariable cox regression model. Directed acyclic graphs were used to assess the minimally sufficient sets of confounding variables. Log rank tests indicated that patients with low FT3 and FT3/FT4 ratio had lower overall survival rates (all p < 0.001). The adjusted HRs for all-cause mortality were 0.48 (95% CI: 0.32-0.73, P = 0.001) when comparing high versus low FT3 and 0.47 (95% CI: 0.32-0.70, P < 0.001) when comparing high versus low FT3/FT4 ratio. Subgroup analyses showed that these associations existed only in elderly patients (≥65 years) and women, after adjustment. In men, only high FT3/FT4 ratio was associated with low all-cause mortality, after adjustment. Routine assessment of FT3 and FT3/FT4 ratio may be a simple and effective way to identify high-risk patients with DFUs, especially in elderly patients and women.