Aim: To review non-disease-specific predictors and causes of primary non-adherence of prescribed pharmaceutical treatments and interventions.
Method: A PubMed literature search (up to October 2015) using the terms primary, initial, first-fill and index with terms related to non-initiation, adherence, compliance, redemption and dispensing. The references, citations and similar articles for the identified articles were used to identify additional sources.
Study selection and data extraction: Prescription record-based and survey-based studies considering at least four medication classes or diseases while evaluating factors (predictors and causes) associated with primary non-adherence were examined.
Results: 53 articles were identified, including 16 specific to cost-related primary non-adherence. Regularly cited factors were age, gender, race and ethnicity, mental health, comorbidities, polypharmacy, medication beliefs, side effects, affordability, education, number of clinic, hospital and emergency department visits, patient-physician relationship, prescriber traits, forgetfulness and convenience. Issues related to affordability were raised most frequently, being brought up in 37of 53 sources. Many of the articles provided conflicting reports as to the direction of predictors and the importance of causes of primary non-adherence.
Conclusion: To date, numerous factors have been identified and associated with primary non-adherence to medications. Some factors may appear to be more influential than others, though the relevance of each predictor and cause varied between studies. To date, discrepant data in the literature has prevented the homogeneous analysis of primary adherence to prescribed pharmaceutical treatments. By compiling the factors and barriers related to primary non-adherence, this investigative review will prompt and promote future research in this area. Ultimately, primary care physicians will be better equipped to understand, act and potentially prevent patients from avoiding treatment regimes at the outset.
Francesca Seal, Andrew J Cave, Lana L Atkinson