BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) inhibit platelet function, and use of these drugs has been associated with bleeding events. The objective of this study was to examine whether the requirement for red blood cell transfusion was increased following preoperative use of SSRIs among patients undergoing coronary artery bypass grafting (CABG).

METHODS: A population-based cohort study of transfusion requirements (red blood cells, fresh frozen plasma, and/or platelets) was conducted among patients undergoing CABG at either Aalborg or Skejby Hospitals between 1 January 1998 and 31 December 2003. All prescriptions for antidepressants, including SSRIs, filled before the date of admission for CABG were identified using prescription databases. Patients were categorized according to use of antidepressants (never users, current users [<90 days before admission for CABG], and former users). Antidepressants were classified according to their action on serotonin and norepinephrine reuptake mechanisms. Relative risk (RR) for transfusion were adjusted for: age; sex; preoperative use of platelet inhibitors (low-dose aspirin [acetylsalicylic acid], clopidogrel, and dipyridamole), NSAIDs and oral anticoagulants; place of surgery; extracorporeal circulation; concomitant valve surgery; and Charlson comorbidity index score.

RESULTS: There were 124 (3.5%) current users of SSRIs among 3454 patients. Adjusted RRs for transfusion among current users of SSRIs, users of nonselective serotonin reuptake inhibitor antidepressants, and users of other antidepressants were 1.1 (95% CI 0.9, 1.3), 0.9 (95% CI 0.6, 1.3), and 1.0 (95% CI 0.7, 1.5), respectively, when compared with never users of any type of antidepressant. The adjusted RR among former SSRI users was 1.0 (95% CI 0.7, 1.4). Risk of re-exploration for bleeding and mortality within 30 days did not differ according to the examined drug-exposure categories.

CONCLUSION: Preoperative use of SSRIs was not associated with any substantially increased requirement for allogeneic red blood cell transfusion among patients undergoing CABG. The main strengths of this study are its relatively large size, the use of prospectively collected data obtained from population-based databases with complete follow-up, and the ability to examine specific types of antidepressants. The limitations include a lack of detailed clinical data regarding other factors that may influence transfusion requirements.