A systematic review of self-administered medication adherence behaviours in people with multiple sclerosis

BACKGROUND In multiple sclerosis (MS), suboptimal medication adherence is associated with subsequent discontinuation, which occurs in ~30-50% of people within 2-years. Medication adherence is critical for realisation of pharmacotherapy benefits and reduced healthcare expenditure. Previous systematic reviews have not included oral DMTs, first introduced in 2010. OBJECTIVE To undertake a systematic review of adherence and persistence rates for self-administered oral and injectable disease modifying therapies (DMTs) in people with MS. METHODS A literature search for publications examining DMT adherence and persistence rates in MS was conducted through databases including PubMed, Web of Science, Scopus and PsycINFO yielding 1,590 records, with 1,150 duplications removed, resulting in 440 abstracts screened. We included peer-reviewed, English written studies for objectively measured self-administered DMTs in samples aged 18+, published between July 1993, and December 2018. Studies reporting combined intravenous and self-administered DMT adherence results were excluded. RESULTS In total, 119 articles were extracted for quantitative synthesis. Preliminary results show 12-month mean adherence (medication possession ratio) for injectable compared to oral DMTs was 71.7% (n = 6) and 83.0% (n = 3), respectively. Mean discontinuation over 12- and 24-months for injectable DMTs were 30.4% (n = 9) and 29.7% (n = 8); and oral DMTs were 25.4% (n = 3) and 16.5% (n = 5), respectively. CONCLUSIONS Medication adherence and persistence remains problematic despite the introduction of oral DMTs. Oral DMT improvements are noted for 12-month adherence and 24-month discontinuation. With limited oral DMT adherence and persistence data, studies are hampered by methodological issues, such as inconsistent adherence and persistence definitions.