Abstract: 【Abstract】 Objective To investigate the influencing factors for lower-extremity deep venous thrombosis （LEDVT） in inpatients with severe drug eruptions. Methods A case-control study was conducted. A total of 96 inpatients with severe drug eruptions （50 males and 46 females） were collected from the Department of Dermatology, the First Affiliated Hospital of Nanjing Medical University from October 2020 to February 2025. Based on the occurrence of LEDVT during hospitalization, the patients were divided into a thrombosis group and a control group （without LEDVT）. Clinical data were compared between the two groups in terms of age, length of hospital stay, body mass index （BMI）, type of drug eruption, initial methylprednisolone dose, the first laboratory test results after admission （including blood routine test results and the levels of albumin, fasting blood glucose, brain natriuretic peptide ［BNP］, C?reactive protein, procalcitonin ［PCT］, and D?dimer）, bilateral lower-extremity vascular ultrasound findings, and Padua scores. Differences in clinical data between groups were analyzed using the two independent samples t?test, one?way analysis of variance, Mann?Whitney U test, Kruskal?Wallis H test, and chi?square test; influencing factors for LEDVT were analyzed using the least absolute shrinkage and selection operator （LASSO） regression and multivariate logistic regression models. Results Among the 96 patients with severe drug eruptions, there were 24 with Stevens-Johnson syndrome （SJS）, 44 with toxic epidermal necrolysis （TEN）, 14 with drug-induced hypersensitivity syndrome （DIHS）, and 14 with erythrodermic drug eruption; 35 patients were classified into the thrombosis group and 61 into the control group. Compared with the control group, the thrombosis group exhibited significantly higher ages （63.0 ± 16.7 years vs. 52.7 ± 20.7 years）, BMI （25.2 ± 2.3 kg/m2 vs. 23.9 ± 2.4 kg/m2）, white blood cell counts （［11.9 ± 6.5］ × 10?/L vs. ［7.0 ± 5.6］ × 10?/L）, red blood cell counts （［4.7 ± 0.8］ × 1012/L vs. ［4.1 ± 0.7］ × 1012/L）, platelet counts （［273.4 ± 65.2］ × 10?/L vs. ［230.2 ± 46.8］ × 10?/L）, fasting blood glucose levels （5.8 ± 1.5 mmol/L vs. 4.8 ± 0.9 mmol/L）, PCT levels （M ［Q1, Q3］: 0.9 ［0.2, 3.3］ μg/L vs. 0.2 ［0.1, 0.4］ μg/L）, BNP levels （999.0 ［422.8, 2 054.0］ ng/L vs. 234.4 ［99.0, 521.0］ ng/L）, D-dimer levels （4.3 ± 2.4 mg/L vs. 1.8 ± 1.3 mg/L）, initial methylprednisolone doses （66.9 ± 19.4 mg/d vs. 46.9 ± 11.5 mg/d）, and Padua scores （4.0 ± 1.4 points vs. 1.9 ± 1.3 points） （all P < 0.05）, but showed significantly lower albumin levels （27.1 ± 3.7 g/L vs. 30.8 ± 5.0 g/L, P < 0.001）. LASSO regression analysis indicated that D-dimer levels, Padua scores, initial methylprednisolone doses, PCT levels, and white blood cell counts were influencing factors for LEDVT in patients with severe drug eruptions. Multivariate logistic regression analysis identified white blood cell counts （OR = 1.23, 95% CI: 1.08 - 1.41）, D-dimer levels（OR = 1.57, 95% CI: 1.05 - 2.36）, initial methylprednisolone doses （OR = 1.06, 95% CI: 1.01 - 1.12） and Padua scores （OR = 2.27, 95% CI: 1.30 - 3.96） as independent influencing factors for LEDVT in patients with severe drug eruptions （all P < 0.05）. Among the SJS, TEN, DIHS, and erythrodermic drug eruption groups, significant differences were observed in the gender ratio, white blood cell counts, C-reactive protein levels, BNP levels, PCT levels, and Padua scores （all P < 0.05）. Specifically, white blood cell counts were significantly higher in the DIHS group than in the TEN group （P = 0.043）, and significantly higher in the erythrodermic drug eruption group than in the SJS group （P = 0.033） and the TEN group （P = 0.009）; the CRP levels were significantly higher in the TEN group than in the SJS group （P = 0.009） and the erythrodermic drug eruption group （P = 0.023）; the PCT levels were significantly higher in both the DIHS and TEN groups than in the SJS group （P < 0.001, = 0.008, respectively）; the BNP levels were significantly higher in the DIHS group than in the SJS group （P < 0.001） and the TEN group （P = 0.039）; the Padua scores were significantly higher in the DIHS group than in the SJS group （P = 0.018）. Conclusion Inpatients with severe drug eruptions who have relatively high white blood cell counts, D-dimer levels, initial methylprednisolone doses, and Padua scores may be more prone to developing LEDVT.

Key words: Drug eruptions, Severe drug eruptions, Venous thromboembolism, Influencing factors, Leukocyte count, D-dimer, Glucocorticoids, Padua score