Risk factors for venous thromboembolism among psychiatric inpatients: a case control study

Psychiatric inpatients have an increased risk of venous thromboembolism (VTE). While previous studies have identified baseline risk factors among psychiatric inpatients, systematic data on in-hospital risk factors associated with clinical conditions or treatment remain scarce. This study aimed to identify specific risk factors for VTE among psychiatric inpatients.

This retrospective, single-center case-control study was conducted at Tokyo Metropolitan Matsuzawa Hospital, Japan. Using the electronic medical record system, data on patients newly diagnosed with VTE during their hospital stay were extracted as cases. For each case, five age- and sex-matched patients who were hospitalized in the same ward during the same month were selected as controls. Multiple logistic regression analysis was conducted to examine the effects of in-hospital risk factors, including retarded catatonia, physical restraint, seclusion, and use of psychotropics, on incident VTE.

During the study period, 11,819 patients were hospitalized. Among them, 108 (0.9 %) patients with VTE, consisting of 37 patients with pulmonary embolism and 71 patients with proximal deep vein thrombosis, were identified. The mean ± SD age of the patients with VTE was 72.5 ± 14.4 years. After adjusting for confounding factors, retarded catatonia (odds ratio [OR]:10.1, 95 % confidence interval [CI]:3.9-25.7, p < 0.001) and physical restraint (OR:6.7, 95 % CI:3.4-13.3, p < 0.001) were significantly associated with a higher risk of VTE. In contrast, the use of anticoagulants was associated with a lower risk (OR:0.3, 95 % CI:0.1-0.6, p = 0.003).

Risk factors for VTE among psychiatric inpatients are markedly different from those among medical inpatients. Further research is warranted to identify potential candidates for anticoagulant prophylaxis against VTE during psychiatric inpatient care.