Hypothyroidism and the Risk of Venous Thromboembolism: A Nationwide Cohort Study

Abstract

Background Previous studies have shown that hypothyroidism may have an impact on blood coagulation. However, how hypothyroidism and thyroxine replacement therapy (TRT) affect the risk of venous thromboembolism (VTE) remains controversial. This study aimed to examine the associations of hypothyroidism and TRT with VTE risks. Materials and Methods This nationwide population-based cohort study was conducted using Taiwan's National Health Insurance Research Database. We enrolled 10,818 hypothyroid patients (the exposed cohort) and 21,636 non-hypothyroid subjects (the unexposed cohort) between 2001 and 2014 after 1:2 exact matching according to age, sex, and index year. Hypothyroid patients were further divided into two groups depending on whether they received TRT or not. Adjusted hazard ratios (aHRs) for VTE were calculated using Fine and Gray competing risk models. Results The mean follow-up period was 7.5 years. Hypothyroidism was significantly associated with a higher risk of VTE (aHR = 1.83 [95% confidence interval [CI]: 1.44–2.33, p < 0.001]). Among hypothyroid patients, the TRT subgroup had a non-significant trend of lower VTE risk than the non-TRT subgroup (aHR = 0.73 [95% CI: 0.52–1.01, p = 0.058]). The analysis for individual events revealed a significant association between TRT use and a lower risk of pulmonary embolism among hypothyroid patients (aHR = 0.34 [95% CI: 0.13–0.88, p = 0.026]). Conclusion The data suggest that hypothyroidism was significantly associated with an increased risk of VTE. Among hypothyroid patients, a non-significant trend of lower VTE risk in patients treated with TRT was observed. Further prospective studies or clinical trials are necessary to confirm causality.

Venous thromboembolism rates and risk factors following endoscopic skull base surgery

“…24 Importantly, this study found that this increased risk was negated with use of thyroid replacement therapy (aHR 0.34 [95% CI 0.13-0.88]). 24 In the perioperative context, correction of existing endocrinopathies, when possible, may represent an actionable strategy to mitigate risk of VTE, particularly if chemoprophylaxis is not a desirable option.…”

“…A recent study of 10,818 patients found a significantly higher association between hypothyroidism and VTE, with an adjusted hazard ratio (aHR) of 1.83 (95% CI 1.44–2.33) 24 . Importantly, this study found that this increased risk was negated with use of thyroid replacement therapy (aHR 0.34 [95% CI 0.13–0.88]) 24 . In the perioperative context, correction of existing endocrinopathies, when possible, may represent an actionable strategy to mitigate risk of VTE, particularly if chemoprophylaxis is not a desirable option.…”

“…Mechanistically, the hypercoagulable state may be due to increased levels of fibrinolysis inhibitors in hypothyroid states 22,23 . A recent study of 10,818 patients found a significantly higher association between hypothyroidism and VTE, with an adjusted hazard ratio (aHR) of 1.83 (95% CI 1.44–2.33) 24 . Importantly, this study found that this increased risk was negated with use of thyroid replacement therapy (aHR 0.34 [95% CI 0.13–0.88]) 24 .…”

Predicting the occurrence of venous thromboembolism: construction and verification of risk warning model

“…Approximately 50% of VTEs are provoked by immobilization, trauma, surgery, or hospitalization in previous 3 months [12][13][14][15], and 20% associated with cancer while 30% unprovoked [16][17][18]. VTE has many risk factors which are constantly multiplied [19][20][21][22][23][24][25]. Currently, Caprini Risk Assessment Scale is widely used in clinical practice.…”

Predicting the occurrence of venous thromboembolism: construction and verification of Risk Warning Model

“…And 20% are associated with cancer while 30% are unprovoked [16][17][18]. VTE has many risk factors which are constantly being updated [19][20][21][22][23][24][25]. Currently, Caprini Risk Assessment Scale is widely used in clinical practice.…”