Systematic review data published in the Journal of Rheumatology describe measures of drug adherence in the rheumatic disease literature. Across 53 intervention studies of rheumatic conditions, 37 different instruments were used to report medication adherence. Efforts to develop standardized outcome measures could improve the ability to compare medication adherence strategies across studies.

Investigators searched MEDLINE, PsycINFO, EMBASE, CINAHL, and CENTRAL from inception through February 2019 for English-language studies assessing medication adherence in patients with any rheumatic condition. Outcome domains were classified into 3 overarching groups: (1) adherence; (2) health outcomes; and (3) adherence-related factors. The first domain was further subdivided into phases: (1) initiation, or time of first medication dose; (2) implementation, or the extent to which patient complied with prescribed medication dosing; and (3) persistence, or the length of time between drug initiation and discontinuation. Health outcomes included any condition-specific outcome domain that could affect medication adherence. Adherence-related factors included any psychosocial factors that could influence medication adherence.

A total of 53 studies were included in analyses, comprising a total study cohort of 26,361 patients. Overall, studies used 37 difference instruments to measure adherence. The most frequently reported instruments were pharmacy refill record (n=20 studies; 38%), pill count (n=7; 13%), the 4-item Morisky scale (n=6; 11%), the Compliance Questionnaire in Rheumatology (n=4; 8%), and the Medication Event Monitoring System (n=4; 8%). Reported phases of adherence included initiation (n=13 studies), implementation (n=32), and persistence (n=27). In 20 studies, the phase of adherence measured was unclear.

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A total of 38 health outcomes were reported in 41 studies. Twenty-four studies reported on medication adverse events. In studies assessing patients with osteoporosis-related conditions (n=33), the most commonly reported health outcomes were adverse events (n=17; 52%), bone turnover markers (n=10; 30%), bone mineral density (n=5; 15%), fractures (n=5; 15%), and quality of life (n=4; 12%). In studies of patients with rheumatoid arthritis (n=12), the most commonly reported health outcomes were disease activity (n=7; 58%), physical function (n=7; 58%), pain (n=5; 42%), quality of life (n=4; 35%), adverse events (n=3; 25%), and erythrocyte sedimentation rate or C-reactive protein (n=3; 25%).

A total of 33 studies reported 32 adherence-related factors. Most frequently, studies would list participants’ self-reported reasons for adherence/nonadherence (n=12; 36%) The next most common factors were medication beliefs (n=8; 15%), illness perception (n=5; 9%), medication satisfaction (n=5; 9%), and satisfaction with medication information (n=5; 9%).

In this systematic review of rheumatic disease interventions, measures of drug adherence were heterogeneous. Efforts to achieve consensus on relevant outcomes can improve coherence between studies. “A core domain set will enhance the ability to compare results across adherence studies on outcomes of significance to patients and others,” investigators wrote.


Kelly A, Crimston-Smith L, Tong A, et al. Scope of outcomes in trials and observational studies of interventions targeting medication adherence in rheumatic conditions: a systematic review.J Rheumatol. Published online Aug 18, 2020.  doi:10.3899/jrheum.190726