Use of selective serotonin reuptake inhibitors and risk of re-operation due to post-surgical bleeding in breast cancer patients: a Danish population-based cohort study

We conducted a population-based study of the risk of re-operation due to post-surgical bleeding within two weeks of primary surgery among Danish women with primary breast cancer. Patients were categorised according to their use of SSRI: never users, current users (SSRI prescription within 30 days of initial breast cancer surgery), and former users (SSRI prescription more than 30 days before initial breast cancer surgery). We calculated the risk of re-operation due to post-surgical bleeding within 14 days of initial surgery, and the relative risk (RR) of re-operation comparing SSRI users with never users of SSRI adjusting for potential confounders.389 of 14,464 women (2.7%) were re-operated. 1592 (11%) had a history of SSRI use. Risk of re-operation was 2.6% among never users, 7.0% among current SSRI users, and 2.7% among former users. Current users thus had an increased risk of re-operation due to post-operative bleeding (adjusted relative risk = 2.3; 95% confidence interval (CI) = 1.4, 3.9) compared with never users. There was no increased risk of re-operation associated with former use of SSRI (RR = 0.93, 95% CI = 0.66, 1.3).Current use of SSRI is associated with an increased risk of re-operation due to bleeding after surgery for breast cancer.Selective Serotonin Reuptake Inhibitors (SSRI) decrease platelet serotonin storage and platelet-function in humans [1,2] and are associated with upper gastrointestinal bleeding [3,4]. This mechanism suggests that SSRI use may increase the risk of post-surgical bleeding, but data on peri-operative risk of bleeding associated with use of SSRI are few and contradicting [5,6]. One Danish study on coronary artery bypass surgery reported no association between the use of SSRI and an increased requirement for blood transfusion [5]. In contrast, a study on orthopaedic surgery found use of SSRI associated with a 3.7-fold increased risk of subsequent blood transfusion [6]. Severe peri-operative bleeding, defined as the need for blood