Assessing disruptions in adherence to antidepressant treatments after breast cancer diagnosis.

PURPOSE: Long-term treatment with antidepressants can lessen the symptoms of depression, but health-related crises-such as a cancer diagnosis-may disrupt ongoing depression care. The study aims to estimate the effect of receiving a breast cancer diagnosis on antidepressant adherence among women with depression.

METHODS: Using SEER-Medicare administrative claims, we identified women aged 65+ with newly diagnosed breast cancer between 2008 and 2011, who were diagnosed with depression and used antidepressants during the year before pre-diagnosis year. We compared antidepressant adherence among women with breast cancer to similar women without cancer using generalized estimation equations. Antidepressant adherence was estimated using the proportion of days covered 1 year before and after the index date.

RESULTS: We included 1142 women with breast cancer and pre-existing depression and 1142 matched non-cancer patients with pre-existing depression. Mean antidepressant adherence was similar for both groups in the year before and after the index date (all around 0.71); adherence decreased by approximately 0.01 following breast cancer diagnosis in cancer group, with similar reductions among non-cancer group (p = 0.19). However, substantial proportion of patients had inadequate adherence to antidepressants in the post-diagnosis period, and almost 40% of patients in each group discontinued antidepressants over the study period.

CONCLUSIONS: Antidepressant adherence was not associated with receiving a breast cancer diagnosis beyond what would have been expected in a similar cohort of women without cancer; however, adherence was poor among both groups. Ensuring adequate ongoing depression care is important to improve cancer care and patient quality of life in the long term. Copyright © 2017 John Wiley & Sons, Ltd.