Complex antithrombotic therapy: determinants of patient preference and impact on medication adherence

Purpose: For years, older patients have been prescribed multiple blood-thinning medications (complex antithrombotic therapy [CAT]) to decrease their risk of cardiovascular events. These therapies, however, increase risk of adverse bleeding events. We assessed patient-reported trade-offs between cardioprotective benefit, gastrointestinal bleeding risk, and burden of self-management using adaptive conjoint analysis (ACA). As ACA could be a clinically useful tool to obtain patient preferences and guide future patient-centered care, we examined the clinical application of ACA to obtain patient preferences and the impact of ACA on medication adherence.

Patients and methods: An electronic ACA survey led 201 respondents through medication risk-benefit trade-offs, revealing patients' preferences for the CAT risk/benefit profile they valued most. The post-ACA prescription regimen was categorized as concordant or discordant with elicited preferences. Adherence was measured using VA pharmacy refill data to measure persistence of use prior to and 1 year following preference-elicitation. Additionally, we analyzed qualitative interviews of 56 respondents regarding their perception of the ACA and the preference elicitation experience.

Results: Participants prioritized 5-year cardiovascular benefit over preventing adverse events. Medication side effects, medication-associated activity restrictions, and regimen complexity were less important than bleeding risk and cardioprotective benefit. One year after the ACA survey, a 15% increase in adherence was observed in patients prescribed a preference-concordant CAT strategy. An increase of only 6% was noted in patients prescribed a preference-discordant strategy. Qualitative interviews showed that the ACA exercise contributed to increase inpatient activation, patient awareness of preferences, and patient engagement with clinicians about treatment decisions.

Conclusion: By working through trade-offs, patients actively clarified their preferences, learning about CAT risks, benefits, and self-management. Patients with medication regimens concordant with their preferences had increased medication adherence at 1 year compared to those with discordant medication regimens. The ACA task improved adherence through enhanced patient engagement regarding treatment preferences.