Factors associated with nonadherence to the use of coumarin derivatives or direct oral anticoagulants: A systematic review of observational studies.

Nonadherence 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 nonadherence 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, 1270 studies were identified and nine studies were selected for this review. In hand searching, 77 studies were found, but none included. The associated factors with nonadherence were heterogeneous, and some factors were described as both risk and protection for nonadherence, 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 nonadherence. In clinical practice, the knowledge on factors associated with nonadherence is helpful to identifying patients at higher risk of complications that would benefit from individualized interventions.