Assessing adherence to multiple medications and in daily life among patients with multimorbidity

Chronic conditions often require multiple medication intake. However, past research has focused on assessing overall adherence or adherence to a single index medication only. This study explored adherence measures for multiple medication intake, and in daily life, among patients with multiple chronic conditions (i.e. multimorbidity).

Eighty-four patients with multimorbidity and multiple-medication regimens completed three monthly panel questionnaires. A randomly assigned subsample additionally completed a 30-day daily diary.

The Non-Adherence Report; a brief self-report measure of adherence to each prescribed medication (NAR-M), and in daily life. We further assessed the Medication Adherence Report Scale (MARS), and a subsample of participants were randomised to electronic adherence monitoring.

The NAR-M indicated M = 94.7% adherence at Time 1 (SD = 9.3%). The NAR-M was significantly correlated with the MARS (r_t1 = .52, r_t2 = .57, and r_t3 = .65; p < .001), and in tendency with electronically assessed adherence (r_t2 = .45, r_t3 = .46, p < .10). Variance components analysis indicated that between-person differences accounted for 10.2% of the variance in NAR-M adherence rates, whereas 22.9% were attributable to medication by person interactions.

This study highlights the importance and feasibility of studying adherence to multiple medications differentially, and in daily life. Future studies may use these measures to investigate within-person and between-medication differences in adherence.