Nonadherence in Outpatient Thrombosis Prophylaxis with Low Molecular Weight Heparins after Major Orthopaedic Surgery
Background: According to some current guidelines, extended thromboprophylaxis after hip and knee arthroplasties is recommended. Outpatient prophylaxis with low molecular weight heparins (LMWH) is an important part of this prophylaxis, although the rates of adherence to these regimens are unknown. We determined (1) the degree of nonadherence (NA) of patients with LMWH outpatient prophylaxis and (2) whether specific independent factors explain NA.
Methods: NA was determined by syringe count and by indirect and direct questions to patients. We defined six different NA indicators. We used three logistic regression models to identify factors explaining LMWH NA.
Results: NA rates ranged between 13% and 21%, depending on the indicator used for measurement. Non-adherent patients missed between 38% and 53% of their outpatient LMWH injections. If patients attended an outpatient rehabilitation program, the probability of their NA increased substantially. Moreover, the NA probability increased with each additional day between acute hospitalization and the start of rehabilitation (linking days). NA was lower for patients who feared thrombosis or believed antithrombotic drugs to be the most important measure in thromboprophylaxis.