Patient Reported Outcomes and Long-Term Non-Adherence to Aromatase Inhibitors.

BACKGROUND Non-adherence to aromatase inhibitors (AIs) is common and increases risk of breast cancer (BC) recurrence. We analyzed factors associated with non-adherence among patients enrolled in S1105, a randomized trial of text-messaging. METHODS At enrollment, BC patients were required to have been on an adjuvant AI for ≥30 days and were asked about financial, medication and demographic factors. They completed Patient-Reported Outcomes (PROs) representing pain (Brief Pain Inventory), endocrine symptoms (FACT-Endocrine Symptoms), and beliefs about medications (Treatment Satisfaction Questionnaire for Medicine; Brief Medication Questionnaire). Our primary endpoint was AI non-adherence at 36 months, defined as urine AI metabolite assay <10 ng/mL or no submitted specimen. We evaluated the association between individual baseline characteristics and non-adherence with logistic regression. A composite risk score reflecting the number of statistically significant baseline characteristics was examined. RESULTS We analyzed data from 702 patients; median age was 60.9 years. Overall, 35.9% patients were non-adherent at 36 months. Younger patients (< age 65 years) were more non-adherent (38.8% vs.28.6%, OR = 1.51,95% CI = 1.05-2.16, p = .02). Fourteen baseline PRO scales were each statistically significantly associated with non-adherence. In a composite risk model categorized into quartile levels, each increase in risk level was associated with a 46.5% increase in the odds of non-adherence (OR = 1.47,95% CI = 1.26-1.70, p < .001). The highest risk patients were more than three times more likely to be non-adherent than the lowest risk patients (OR = 3.14, 95% CI = 1.97-5.02, p < .001). CONCLUSIONS The presence of multiple baseline PRO-specified risk factors was statistically significantly associated with AI non-adherence. The use of these assessments can help identify patients for targeted interventions to improve adherence.