A focus of population health is to evaluate for the presence of societal disparities so that a proactive approach can be taken to address these inequities. Adherence to adjuvant endocrine therapy (AET) among women with hormone receptor-positive (HR+) BC is critical to help decrease morbidity and mortality.
Using data from two large integrated healthcare systems, Henry Ford Health System and Kaiser Permanente Georgia, investigators examined AET adherence using three difference methods: (1) proportion of days covered (PDC), which refers to the number of days that the member was covered with an AET supply divided by 365; (2) the total medication gap, which refers to the total number of days in the year after the first AET fill that the person was not covered with an AET supply; and (3) whether the number of pills dispensed in prescriptions from the date of the first prescription to the end of the follow-up covered at least 80% of the days in the entire period.
To be included in the study sample, women had to self-identify as either black (African American) or white (European American) and had to have HR+ tumors during the study period of January 1, 1998 to December 31, 2012. AETs that were studied included tamoxifen, anastrozole, and exemestane. Data from women who filled at least one prescription for AET up to 1 year following their BC diagnosis and before the diagnosis of recurrence were analyzed. The women also had to be continuously enrolled with the provider organization for a year before the first AET fill through a year after the first AET fill. Initiation of AET was confirmed through pharmacy electronic records.
The total study sample consisted of 1,925 women with HR+ BC, 63% of whom were white and 37% who were black. The mean age of the study population was 59.5 years, and 23.3% were aged 25 to 49 years.
Some findings were that the black women who participated tended to be younger than white women (57.9 years vs. 60.3 years); resided in an area of lower socioeconomic status (40.4% vs. 14%); were less likely to possess health maintenance [HMO] organization benefits (78% vs. 85%); had later stage disease (8.9% vs. 6.4%) and higher tumor grade (32.3% vs. 20.6%); more often had smaller tumors (44.7% vs. 37.7%); and had more comorbid conditions (27.6% vs. 22.1%).
Regarding adherence, a total of 80% of women had a PDC >80%, which was considered to be adherent with treatment. Factors associated with adherence included older age, white race, having smaller tumors (0-0.2 cm), and belonging to an HMO.
When medication gaps of <10 days were assessed, 55.5% of the study sample were without AETs for 10 days or more. Once again, age and race were significantly associated with adherence.
When the total number of days of AET medication gap was calculated over a 12-month period, black women had a gap of 23.5 days compared with a gap of 11.0 days for white women. Younger women also tended to be less adherent as assessed via this model.
The authors were unable to examine social determinants of their findings, but they postulated that potential reasons for these disparities in race and age for adherence were due to medication costs, pharmacy type (mail or retail), physician recommendation, socioeconomic status, or longer prescription-refill intervals. Cost and concern over adverse effects may be factors affecting adherence among young women. These areas need to be further explored.
For pharmacists, being able to identify nonadherence early gives them an opportunity to take a more proactive approach to the care of the BC patient.
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