Title: What Medications Are Most Prescribed but Never Filled? Predictors of Nonadherence in Medicare 5-Star Population
Authors: Caleb Williams, Nadia Hason, Naomi Yates
Contact: Caleb.x.williams@kp.orgObjective:
Primary: Evaluate the most abandoned therapies within the Medicare 5-Star population
Secondary: Compare the different demographic factors (gender, age, race, ethnicity) and measurable factors (PCP relationship, mail order utilization, comorbidities, lab values) and how they influence first fill adherence in the Medicare 5-Star population
Self-Assessment Question:
Which factor was consistently associated with increased medication adherence across all therapeutic categories (hypertension, diabetes, and high cholesterol)?
a) Age
b) Female gender
c) Mail order pharmacy (answer)
d) Race (black vs white)
Background:Medication adherence significantly impacts patient outcomes and healthcare costs in the United States, particularly for chronic conditions such as diabetes, hypercholesterolemia and hypertensions. The first fill of a new maintenance medication is critical for establishing long-term therapy success, as failure to initiate treatment can indefinitely delay care, increase the risk of complications, and contribute to over $170 billion in annual healthcare expenditures. Identifying and addressing barriers is essential for improving early adherence and optimizing patient outcomes.
Methods:This is a retrospective, IRB-exempt cohort study that included all Medicare 5-Star patients who were prescribed but did not fill generic oral diabetes, antihypertensives and/or statin medications from May 31
st, 2023, to June 1
st, 2024. Patients not enrolled at Kaiser Permanente through the full study duration were excluded. The primary outcome was to identify the most frequently abandoned therapies within the Medicare 5-Star population. The secondary outcome was to compare the different demographic factors, such as gender, age, race, ethnicity or measurable factors such as a lack of PCP relationship, underutilization of mail order, comorbidities, laboratory values and how they influence first fill adherence.
Results:Between 5/31/2023 and 6/1/2024, a total of 27,674 Medicare 5-Star patients were included in the analysis of first-fill adherence for diabetes, hypertension, and statin medications. Among these, 6,408 were prescribed an oral diabetes medication, 17,714 were prescribed a hypertension medication, and 17,305 were prescribed a statin medication. The overall first-fill rates were highest for hypertension medications (97.9%), followed by statins (96.5%) and diabetes medications (95.0%).
Several factors were significantly associated with higher odds of filling a first prescription across all three medication classes. A recent primary care provider (PCP) visit within the last 12 months was the strongest predictor of first-fill adherence, with odds ratios (OR) of 3.08 (95% CI: 2.47–3.83) for hypertension medications, 2.30 (95% CI: 1.92–2.75) for statins, and 1.81 (95% CI: 1.39–2.35) for diabetes medications (p < 0.0001 for all). Enrollment in kp.org was also associated with increased adherence, with ORs of 1.61 (95% CI: 1.24–2.09) for hypertension medications, 1.36 (95% CI: 1.09–1.71) for statins, and 1.48 (95% CI: 1.09–2.02) for diabetes medications (p < 0.05 for all).
Conversely, depression or the use of antidepressants was associated with lower adherence. Patients with depression had lower odds of filling their initial antihypertensive (OR 0.72, 95% CI: 0.56-0.91) or antidiabetic prescriptions (OR 0.64, 95% CI: 0.49 – 0.833, p < 0.05 for both). Additionally, racial disparities were observed, as Black/African American patients were significantly less likely to fill their first prescription compared to White patients for both diabetes (OR 0.72, 95% CI: 0.55–0.95) and statin medications (OR 0.74, 95% CI: 0.61–0.90, p < 0.05 for both).
Use of mail order pharmacy was strongly associated with first-fill adherence across all medication groups. Patients who used mail order had significantly higher odds of filling their first prescription compared to those using retail pharmacy, with ORs of 2.35 (95% CI: 1.89–2.93) for hypertension medications, 2.28 (95% CI: 1.92–2.71) for statins, and 1.78 (95% CI: 1.40–2.28) for diabetes medications (p < 0.0001 for all).
Conclusion:This study aimed to identify key factors associated with first-fill adherence for diabetes, hypertension, and statin medications among Medicare 5-star patients. The findings suggest that patients with recent PCP visits, kp.org enrollment, and mail order pharmacy use were significantly more likely to fill their first prescription, while those with depression or taking antidepressants and certain racial/ethnic backgrounds exhibited lower adherence rates.
