A Review of Factors Influencing the Three Phases of Medication Adherence in People with Attention-Deficit/Hyperactivity Disorder

Objectives: Factors affecting adherence to medications in people with attention-deficit/hyperactivity disorder (ADHD) are not well understood in the context of their influence on the different phases of adherence, that is, initiation, implementation, and discontinuation. This review aimed to identify the factors affecting the three phases of medication adherence in people with ADHD. Methods: Six electronic databases, including Medline, PubMed, IPA, CINAHL, Embase, and PsycINFO, were systematically searched from inception through October 2018 with the limitations of English language and human studies. The search strategy was based on three concepts (adherence, ADHD, and factors) and their relevant terminologies. Results: Considerable variability was observed with regards to the criteria used to define adherence in identified studies (n = 48). Most studies focused on the implementation phase of adherence (n = 27), while only a handful focused on the initiation (n = 6) and discontinuation (n = 5) phase of adherence. The remaining studies (n = 10) examined multiple phases of adherence. Conflicting information received about medication, medication frequency, and fears of medication's effect on growth were the unique factors impacting initiation, implementation, and discontinuation, respectively. Moreover, factors within each phase of adherence also differed with different populations such as parents, children, adolescents, and adults. Fear of addiction, medication effectiveness, psychiatric comorbidity, and medication side effects were the most common factors identified in all three phases of adherence. Conclusions: This review found some unique factors in each phase of adherence while some overlap was also noted. Future interventions to improve adherence should be phase-and group specific rather than consider adherence as a single variable.