No difference in patient compliance between full-strength versus low-dose aspirin for VTE prophylaxis following total hip and total knee replacement

Introduction The utilization of aspirin for VTE prophylaxis following TJA has increased due to updated clinical practice guidelines. Aspirin is the only approved VTE prophylaxis medication that does not require a prescription, but adherence and tolerance remain unknown. We hypothesized decreased patient compliance utilizing full-strength 325 mg aspirin twice daily following TJA when compared to low-dose 81 mg twice daily. We also investigated the reasons why patients may elect to stop the medication earlier than 28 days. Methods A consecutive series of patients undergoing primary total hip or knee arthroplasty utilizing 325 or 81 mg of EC aspirin twice daily for 4 weeks were surveyed to determine compliance with use and any adverse events related to the medication. Fisher's exact test was used to determine statistical significance. Results 404 patients were enrolled with 199 patients prescribed the 325 mg regimen. Fifty-two patients who were prescribed 325 mg missed a dose versus 51 patients who were prescribed 81 mg (p = 0.082). No significant difference in the frequency of missed doses (missing < 5 doses, 5-10 doses, > 10 doses) between the treatment regimens (p = 0.78, 0.39 and 0.83, respectively). Most commonly cited reason for stopping aspirin in both treatment groups was gastrointestinal issues (10.5% and 7%, respectively). Discussion and Conclusions By surveying patients on their use of aspirin we find no difference in adherence between full-strength and low-dose treatment regimens. Additionally, we have a better understanding of the reasons for noncompliance as GI upset was a relatively common complaint with both doses.