Background: Comorbidity among breast cancer (BC) survivors increases risk of overall mortality and recent reports have described some comorbid conditions to possibly influence risk of second BC events and BC-specific mortality. Therefore, clinical management of chronic conditions such as hypertension (HTN), diabetes mellitus (DM) and dyslipidemias in BC survivors may be important to both cancer- and non-cancer-related outcomes. Medication adherence for chronic conditions such as diabetes is poor in general populations and quality of care may be further impacted by BC diagnosis/treatment. The objective of this study was to describe characteristics associated with nonadherence to medications to treat HTN, DM and dyslipidemias among BC survivors enrolled in a large, integrated health plan.

Methods: Retrospective cohort of 4,216 BC survivors, the Commonly Used Medications and Breast Cancer Outcomes (COMBO) study at Group Health Cooperative. Women in our analysis were diagnosed with stages I-II BC between 1990-2008 and alive and without recurrence or second primary BC in the year 365 days post-BC diagnosis (days 366-730). Medication users were identified by ≥1 dispensings of antihypertensives, oral DM medications, and/or statins. Data on incident BC, patient characteristics, and medications was obtained via linkage to the western Washington SEER registry, medical record and automated health plan data including pharmacy dispensing records. Medication adherence was measured using medication possession ratio (MPR) and classified as non-adherent if MPR<0.80. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for nonadherence vs adherence to antihypertensives, oral DM medications and statins by various characteristics using multivariate logistic regression.

Results: We identified 1,929 prevalent users of antihypertensives (n=1,779), DM medications (n=499) and/or statins (n=1,072). 37% were non-adherent to antihypertensives; 75% were non-adherent to DM medications; 39% were non-adherent to statins. In adjusted models, younger women (ages <50, 50-64) were more likely to be non-adherent to all 3 therapeutic classes compared to older women (ages ≥65). Women who received radiation therapy (OR=1.21 95% CI 1.00-1.47) or endocrine therapy (OR=1.25 95% CI 1.03-1.52) were more likely to be non-adherent to antihypertensives; women treated with chemotherapy (OR=1.67 95% CI 1.03-2.69) were more likely to be non-adherent to DM medications. Greater BMI (P=0.001) and more frequent primary care provider visits (≥2 vs 0-1 only; OR=0.30 95% CI 0.24-0.38) were associated with better adherence to antihypertensives. Likewise, higher Charlson comorbidity scores (≥2 vs <2) were associated with greater adherence to DM medications (OR=0.49 95% CI 0.23-0.83) and statins (OR=0.54 95% CI 0.28-1.02).

Conclusion: In this population-based cohort of BC survivors, nonadherence to medications for HTN, DM, and dyslipidemias was associated with younger age, and impact of specific BC treatments on medication adherence varied by therapeutic indication. Additional research is warranted to target patients in need of medication management as well as to explore patient preferences and provider factors that may influence medication adherence.

Citation Format: Gregory S Calip, Denise M Boudreau. Characteristics associated with nonadherence to medications for hypertension, diabetes, and dyslipidemias among breast cancer survivors [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr PD4-6.