Objective To investigate the effects of compression treatment on occurrence of venous thromboembolism (VTE) after tension-free inguinal hernia repair.

Methods The retrospective cohort study was conducted. The clinical data of 13 263 patients with inguinal hernia who were admitted to 58 medical centers from January to December in 2017 were collected, including 1 668 in Beijing Chaoyang Hospital of Capital Medical University, 782 in East Hospital Affiliated to Tongji University, 558 in Huadong Hospital of Fudan University, 525 in Sir Run Run Shaw Hospital of Zhejiang University School of Medicine, 488 in Ruijin Hospital of Shanghai Jiaotong University School of Medicine, 382 in Tianjin People's Hospital, 378 in Peking University Third Hospital, 364 in Beijing Hospital, 356 in Shengjing Hospital of China Medical University, 348 in Huashan Hospital of Fudan University, 348 in Sichuan Provincial People's Hospital, 328 in Affiliated Hospital of Zunyi Medical University, 304 in Beijing Luhe Hospital of Capital Medical University, 296 in People's Hospital of Changshou District in Chongqing, 290 in Anhui Provincial Hospital, 281 in the First Affiliated Hospital of Dalian Medical University, 281 in Xinjiang Uygur Autonomous People's Hospital, 247 in Qilu Hospital of Shandong University, 220 in Wuhan NO.1 Hospital, 214 in the First Hospital of China Medical University, 213 in West China Hospital of Sichuan University, 206 in the Second Affiliated Hospital of Chongqing Medical University, 202 in Taiyuan Central Hospital of Shanxi Medical University, 197 in the First Affiliated Hospital of Wenzhou University, 191 in Zhongda Hospital of Southeast University, 190 in Tianjin Medical University General Hospital, 189 in Xuzhou Central Hospital, 188 in the First Affiliated Hospital of Harbin Medical University, 187 in the Second Hospital Affiliated to Naval Medical University, 175 in Chengdu Fifth People's Hospital, 173 in Tianjin Nankai Hospital, 172 in the Fourth Affiliated Hospital of China Medical University, 172 in Zhangjiakou First Hospital, 161 in Henan Provincial People's Hospital, 153 in the First Affiliated Hospital of Xi'an Jiaotong University, 149 in Shandong Provincial Hospital, 142 in the Second Hospital of Shandong University, 137 in the First Affiliated Hospital of Hunan University of Medicine, 136 in the Fourth Hospital of Harbin Medical University, 127 in Pingjiang District of the First Affiliated Hospital of Soochow University, 102 in the Central Hospital of Wuhan, 100 in the First Affiliated Hospital of Soochow University, 98 in Peking Union Medical College Hospital of Chinese Academy of Medical Sciences, 97 in the First Affiliated Hospital of Chongqing Medical University, 96 in Xijing Hospital Affiliated to Air Force Medical University, 90 in the Fourth Medical Center of Chinese PLA General Hospital, 81 in Hunan Provincial Hospital of Traditional Medicine, 80 in the First Hospital of Tsinghua University, 80 in Xinhua Hospital of Hubei Province, 61 in the First Affiliated Hospital of Zhengzhou University, 57 in Peking University International Hospital, 50 in Peking University First Hospital, 39 in Zhongnan Hospital of Wuhan University, 38 in Jilin Yan'an Hospital, 37 in China-Japan Union Hospital of Jilin University, 20 in Taikang Xianlin Drum Hospital, 16 in Chinese PLA General Hospital, 3 in the First Affiliated Hospital of Fujian Medical University. There were 11 852 males and 1 411 females, aged from 18 to 102 years, with a median age of 64 years. Of 13 263 patients, 9 995 with compression treatment after tension-free inguinal hernia repair were divided into compression group and 3 268 without compression treatment after tension-free inguinal hernia repair were divided into non-compression group. Observation indicators: (1) compression treatment of patients in the compression group; (2) occurrence of VTE after tension-free inguinal hernia repair in the two groups; (3) analysis of influencing factors for VTE after tension-free inguinal hernia repair. Follow-up using telephone interview was performed to detect history of patient's thrombosis, medical history of patient's family and the incidence of postoperative VTE up to February 2018. Measurement data with skewed distribution were represented as M (P25,P75) or M (range), and comparison between groups was analyzed using the Wilcoxon rank sum test. Count data were described as absolute numbers or percentages, and comparison between groups was analyzed using the chi-square test. Univariate analysis and multivariate analysis were conducted using the Logistic regression model.

Results (1) Compression treatment of patients in the compression group: of the 9 995 patients in the compression group, 6 086 underwent compression treatment with 0.5 kg of sandbag or 500 mL of packed 0.9% sodium chloride solution, 1 881 underwent compression treatment with trusses, 745 underwent compression treatment with girdles, 675 underwent compression treatment with elastic underwear combined with 0.5 kg of sandbag, and 608 underwent compression treatment with elastic underwear. (2) Occurrence of VTE after tension-free inguinal hernia repair in the two groups: patients of the two groups after matching were followed up. Occurrence of VTE after matching were 15 and 1 in the compression group and non-compression group, respectively, showing no significant difference between the two groups (χ²=2.010, P>0.05). (3) Analysis of influencing factors for VTE after tension-free inguinal hernia repair: results of univariate analysis showed that cases with varix of lower limb, cases with oral contracep-tives or hormone replacement therapy history, cases with VTE history, clinical classification, clinical typing, surgical method, cases with anticoagulant drugs history, cases undergoing oral antiplatelet drugs, cases undergoing postoperative VTE prevention with medication were related factors for occurrence of VTE after tension-free inguinal hernia repair (odds ratio=13.98, 37.71, 19.21, 4.43, 4.21, 0.07, 0.08, 0.10, 31.04, 95% confidence interval: 3.15‒62.11, 8.35‒170.24, 6.15‒60.00, 1.43‒13.76, 1.20‒14.82, 0.01‒0.49, 0.02‒0.27, 0.04‒0.29, 8.53‒112.93, P<0.05). Results of multivariate analysis showed that cases with VTE history and surgical method were independent influencing factors for occurrence of VTE after tension-free inguinal hernia repair (odds ratio=7.78, 11.19, 95% confidence interval: 2.06‒29.42, 1.45‒86.55, P<0.05).

Conclusion Cases with VTE history and surgical method are independent influencing factors for occurrence of VTE after tension-free inguinal hernia repair.