Factors associated with non-adherence to the use of coumarin derivatives or direct oral anticoagulants: a systematic review of observational studies

Non-adherence to thromboprophylaxis treatment with oral anticoagulants (OAC) is a public health problem and may be associated with high mortality rates. We sought to synthesize the factors associated with non-adherence to therapy with coumarin derivatives or direct oral anticoagulants. A systematic review was performed at electronic databases Medline, Embase, CINAHL, Lilacs and grey literature (Google Scholar, MedNar, OpenGray, ProQuest Dissertations and Theses and hand search). This study was conducted according to Cochrane's method and PRISMA. The registration on PROSPERO is CRD42020223555. Overall, 1,270 studies were identified and nine studies were selected for this review. In hand search, 77 studies were found, but none included. The associated factors with non-adherence were heterogeneous, and some factors were described as both risk and protection for non-adherence, with few variables showing consistent results among the studies. Variables reported only as risk factors were "male sex"; "hospitalization"; "Charlson score" and "bleeding", while "white race"; CHA DS VASc (score range 2-9)" and "polypharmacy" were reported only as protective factors. Most studies did not present details in the description of concepts and methods to assess non-adherence. In clinical practice, the knowledge on factors associated with non-adherence is helpful to identifying patients at higher risk of complications that would benefit from individualized interventions.