REAL-WORLD PERSISTENCE AND SWITCHING PATTERNS AMONG FIRST-LINE AROMATASE INHIBITORS IN POSTMENOPAUSAL BREAST CANCER IN GREECE: EVIDENCE FROM THE NATIONAL E-PRESCRIPTION DATABASE (2020-2022)
Author(s)
George Gourzoulidis, PhD1, Catherine Kastanioti, PhD1, George Mavridoglou, PhD2, Anastasios Tsolakidis, PhD3, Konstantinos Mathioudakis, PhD3, Charalampos Tzanetakos, MSc4.
1Department of Business Administration & Organizations, University of the Peloponnese, Kalamata, Greece, 2Department of Accounting and Finance, University of the Peloponnese, Antikalamos, Kalamata, Greece, 3IDIKA SA - E-Government Center for Social Security Services, Athens, Greece, 4Health Through Evidece (HTE), Athens, Greece.
1Department of Business Administration & Organizations, University of the Peloponnese, Kalamata, Greece, 2Department of Accounting and Finance, University of the Peloponnese, Antikalamos, Kalamata, Greece, 3IDIKA SA - E-Government Center for Social Security Services, Athens, Greece, 4Health Through Evidece (HTE), Athens, Greece.
OBJECTIVES: Despite being considered therapeutically equivalent, aromatase inhibitors (AIs) may differ in real-world use. This study compared persistence, switching, and costs among first-line AIs in postmenopausal woman with Breast Cancer (BC) in Greece.
METHODS: A retrospective observational study was conducted using anonymized nationwide electronic prescription data from IDIKA S.A. covering January 2020 to December 2022. Postmenopausal women (≥55 years at index) initiating first-line AI with no prior endocrine therapy (aromatase inhibitor, tamoxifen, fulvestrant, or LHRH analog) in a 6-month pre-index window were included (index ≥ July 2020). Follow-up extended from index to first within-class switch (change from one AI to another AI), study end (December 2022), or 60-day prescription gap. Time-to-first switch (primary outcome) was analyzed using Kaplan-Meier methods and Cox proportional hazards models adjusted for age, calendar year, CDK4/6 inhibitor co-medication, and baseline breast cancer treatment complexity. Secondary outcomes were persistence duration and total expenditure during persistence, with cost-per-day calculated to control for treatment duration.
RESULTS: Among 13,392 incident endocrine-therapy-naive postmenopausal AI initiators (median age 71), 89.4% initiated letrozole, 6.8% exemestane, and 3.8% anastrozole. During a median follow-up of 471 days, 436 (3.3%) experienced a within-class switch. Adjusted hazard of switching was significantly higher for anastrozole (HR 1.87; 95% CI 1.22-2.85; p=0.004) and exemestane (HR 1.93; 95% CI 1.43-2.60; p<0.001) versus letrozole. Median persistence was 218 days (letrozole; IQR 113-417), 204 (exemestane), and 180 (anastrozole). Median total expenditure during persistence was €201.78 (letrozole), €220.20 (exemestane), and €137.75 (anastrozole). Cost-per-day was similar for letrozole (€0.85) and anastrozole (€0.83) but 30% higher for exemestane (€1.11; Kruskal-Wallis p<0.001).
CONCLUSIONS: Letrozole initiation was associated with lower observed switching rates and longer persistence than anastrozole or exemestane, while maintaining a daily treatment cost comparable to anastrozole. These findings may inform value-based prescribing and contracting decisions for endocrine therapy in postmenopausal BC.
METHODS: A retrospective observational study was conducted using anonymized nationwide electronic prescription data from IDIKA S.A. covering January 2020 to December 2022. Postmenopausal women (≥55 years at index) initiating first-line AI with no prior endocrine therapy (aromatase inhibitor, tamoxifen, fulvestrant, or LHRH analog) in a 6-month pre-index window were included (index ≥ July 2020). Follow-up extended from index to first within-class switch (change from one AI to another AI), study end (December 2022), or 60-day prescription gap. Time-to-first switch (primary outcome) was analyzed using Kaplan-Meier methods and Cox proportional hazards models adjusted for age, calendar year, CDK4/6 inhibitor co-medication, and baseline breast cancer treatment complexity. Secondary outcomes were persistence duration and total expenditure during persistence, with cost-per-day calculated to control for treatment duration.
RESULTS: Among 13,392 incident endocrine-therapy-naive postmenopausal AI initiators (median age 71), 89.4% initiated letrozole, 6.8% exemestane, and 3.8% anastrozole. During a median follow-up of 471 days, 436 (3.3%) experienced a within-class switch. Adjusted hazard of switching was significantly higher for anastrozole (HR 1.87; 95% CI 1.22-2.85; p=0.004) and exemestane (HR 1.93; 95% CI 1.43-2.60; p<0.001) versus letrozole. Median persistence was 218 days (letrozole; IQR 113-417), 204 (exemestane), and 180 (anastrozole). Median total expenditure during persistence was €201.78 (letrozole), €220.20 (exemestane), and €137.75 (anastrozole). Cost-per-day was similar for letrozole (€0.85) and anastrozole (€0.83) but 30% higher for exemestane (€1.11; Kruskal-Wallis p<0.001).
CONCLUSIONS: Letrozole initiation was associated with lower observed switching rates and longer persistence than anastrozole or exemestane, while maintaining a daily treatment cost comparable to anastrozole. These findings may inform value-based prescribing and contracting decisions for endocrine therapy in postmenopausal BC.
Conference/Value in Health Info
2026-11, ISPOR Europe 2026, Vienna, Austria
Value in Health, Volume 29, Issue 12S
Code
EPH133
Topic
Clinical Outcomes, Epidemiology & Public Health, Health Technology Assessment
Topic Subcategory
Public Health
Disease
Oncology