Interventions to promote adherence to endocrine therapy among breast cancer survivors: A meta-analysis

Adjuvant endocrine therapy (AET) significantly reduces risk of breast cancer recurrence in those patients whose tumor tests hormone (estrogen and/or progesterone) receptor positive. Many who are prescribed AET do not adhere adequately. Studies have sought to examine the effects of interventions to enhance patients' AET adherence, with strikingly mixed results. In order to reconcile a disparate literature, this paper aims to (1) quantitatively review the aggregate effect of interventions designed to optimize AET adherence within the current literature and (2) meta-analyze these effects across studies' by intervention design.

Duplicate searches were conducted using multiple electronic databases as well as hand searches of recent year conference abstracts. Studies were included that (1) tested an intervention to promote AET adherence; (2) reported at least one measure of medication adherence; and (3) reported (or provided upon request) data sufficient to calculate effect size. Effect sizes were calculated using random effects models.

Seven studies representing eight unique interventions were included. We observed an overall null effect across all interventions (k = 8; d [95% CI] = 0.28 [-0.05, 0.61]); however, sensitivity analyses showed that interventions that used bi-directional communication showed statistically significant effects relative to control groups within each study (k = 4; d [95% CI] = 0.59 [0.23, 0.95]) while those relying only on providing information to the patient (one-way communication) did not (k = 4; d [95% CI] = -0.03 [-0.27, 0.20]).

Interventions that promote patient self-report may improve AET adherence through enhancing patient engagement. Investigators and clinicians who wish to optimize medication adherence in this population can consider this approach.