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, Theodore Kotsilieris, PhD1, Anastasios Tsolakidis, PhD3, Konstantinos Mathioudakis, PhD3, Elpida Fotiadou, PhD4, Christianna Makri, MSc5, Charalampos Tzanetakos, MSc6.
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, 4IDIKA SA – E-Government Center for Social Security Services, Athens, Greece, 5Institute of Life – IASO, Athens, Greece, 6Health 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, 4IDIKA SA – E-Government Center for Social Security Services, Athens, Greece, 5Institute of Life – IASO, Athens, Greece, 6Health 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