Purpose: To estimate the use of intermittent androgen deprivation (IAD) therapy in patients with prostate cancer (PCa).
Methods: Retrospective, non-interventional study based on electronic pharmacy dispensation data of luteinizing hormone-releasing hormone (LHRH) analogs and anti-androgens in Catalonia (Spain). Intermittency was defined as the percentage of time off treatment (%IAD), which was calculated for the whole sample by dividing the sum of all off-IAD periods by the total time on any LHRH analog regimen. The prevalence of patients on an IAD regimen (PIAD ) was also estimated. A small validation study based on data from clinical records confirmed the excellent sensitivity and specificity of this approach.
Results: A total of 515 803 prescriptions for LHRH analog were dispensed over a 5-year period (2008 to 2012) to 35 089 PCa patients. The mean age (±SD) was 77 years (±9). The %IAD in the cohort was 1.7% whereas the 5-year prevalence (PIAD ) was 4.2%. Only 2.5% of patients on IAD were on IAD for >6 months. Of the physicians (n = 1638) who prescribed hormonal treatment, 24% used IAD at least once. Total expenditures for LHRH analogs were 1.2% of total drug expenditure in this population.
Conclusions: This study confirms the validity of the method developed to estimate IAD use based on electronic pharmacy dispensation data. Given the large potential clinical and economic benefits that greater use of IAD could provide, future studies are needed to confirm these findings and to identify new strategies to increase the use of IAD.
Keywords: LHRH analogs; appropriateness; intermittent androgen deprivation therapy; overtreatment; pharmacoepidemiology; prostate cancer.
© 2019 John Wiley & Sons, Ltd.