Effect of Polypharmacy on Adherence to Adjuvant Endocrine Therapy for Breast Cancer
In a retrospective cohort study reported in the Journal of Oncology Practice, Calip et al found that polypharmacy overall was associated with increased adherence to adjuvant endocrine therapy for breast cancer. However, frequent use of some medication classes was associated with decreased adherence.
Study Details
The study included data on 40,009 women with incident invasive breast cancer starting adjuvant endocrine therapy with tamoxifen, letrozole, anastrozole, or exemestane between 2009 and 2013 in the Truven Health MarketScan Database. Polypharmacy and pill burden were measured for common medications, including lipid-lowering drugs, antihypertensive agents, oral diabetes medications, insulin analogs, antidepressants, anxiolytics/antipsychotics, and opioid-containing analgesics.
Polypharmacy was defined as frequent use (≥ 3 pharmacy dispensing) of a specific medication class and by pill burden (total dispensings). Medication possession ratios (MPRs) were estimated for 12-month intervals; adherence was defined as an MPR ≥ 0.80.
Association With Adherence
Among all women, 74% were adherent to endocrine therapy in year 1, with a mean MPR of 0.79 being found among those continuing therapy through year 3. Overall, increasing polypharmacy (P < .001) and pill burden (P < .001) were associated with increased adherence.
Compared with women who had no frequent use of any other medication classes, those with frequent use of 1 or 2 classes (odds ratio [OR] = 1.18, 95% confidence interval [CI] = 1.14–1.22), 3 or 4 classes (OR = 1.33, 95% CI = 1.26–1.41), or ≥ 5 classes (OR = 1.40, 95% CI = 1.24–1.58) were more likely to be adherent to endocrine therapy. Compared with women in the lowest quartile of pill burden (0–3 pharmacy dispensings), those in the second quartile (4–8; OR = 1.04, 95% CI = 0.97–1.11), third quartile (9–16; OR = 1.17, 95% CI = 1.09–1.25), and fourth quartile (≥ 17; OR = 1.22, 95% CI = 1.13–1.32) were more likely to be adherent.
Associations by Medication Class
Associations with adherence differed according to medication class. The likelihood of adherence to endocrine therapy was increased with frequent use of lipid-lowering drugs (OR = 1.42, 95% CI = 1.36–1.49) and antihypertensive agents (OR = 1.15, 95% CI = 1.10–1.20) and decreased with frequent use of opioid-containing analgesics (OR = 0.80, 95% CI = 0.77–0.83), anxiolytics/antipsychotics (OR = 0.95, 95% CI = 0.91–0.99), antidepressants (OR = 0.85, 95% CI = 0.82–0.89), and insulin (OR = 0.82, 95% CI = 0.72–0.95).
The investigators concluded: “Associations between polypharmacy and adherence in breast cancer may be better characterized by understanding specific classes of medications used concurrently. Comprehensive medication therapy management, including ongoing pain evaluation and psychoactive therapies, is warranted.”
Gregory S. Calip, PharmD, MPH, PhD, of the Center for Pharmacoepidemiology and Pharmacoeconomic Research, University of Illinois at Chicago, is the corresponding author of the Journal of Oncology Practice article.
The study was supported by Dr. Calip.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
