Reduction in physician reimbursement and use of hormone therapy in prostate cancer

Abstract

Background: Use of androgen suppression therapy (AST) in prostate cancer increased more than threefold from 1991 to 1999. The 2003 Medicare Modernization Act reduced reimbursements for AST by 64% between 2004 and 2005, but the effect of this large reduction on use of AST is unknown.

Methods: A cohort of 72,818 men diagnosed with prostate cancer in 1992-2005 was identified from the Surveillance, Epidemiology, and End Results database. From Medicare claims data, indicated AST was defined as 3 months or more of AST in the first year in men with metastatic disease (n = 8030). Non-indicated AST was defined as AST given without other therapies such as radical prostatectomy or radiation in men with low-risk disease (n = 64,788). The unadjusted annual proportion of men receiving AST was plotted against the median Medicare AST reimbursement. A multivariable model was used to estimate the odds of AST use in men with low-risk and metastatic disease, with the predictor of interest being the calendar year of the payment change. Covariates in the model included age in 5-year categories, clinical tumor stage (T1-T4), World Health Organization grade (1-3, unknown), Charlson comorbidity (0, 1, 2, ≥ 3), race, education, income, and tumor registry site, all as categorical variables. The models included variations in the definition of AST use (≥ 1, ≥ 3, and ≥ 6 months of AST). All statistical tests were two-sided.

Results: AST use in the low-risk group peaked at 10.2% in 2003, then declined to 7.1% in 2004 and 6.1% in 2005. After adjusting for tumor and demographic covariates, the odds of receiving non-indicated primary AST decreased statistically significantly in 2004 (odds ratio [OR] = 0.70, 95% confidence interval = 0.61 to 0.80) and 2005 (OR = 0.61, 95% confidence interval = 0.53 to 0.71) compared with 2003. AST use in the metastatic disease group was stable at 60% during the payment change, and the adjusted odds ratio of receiving AST in this group was unchanged in 2004-2005.

Conclusions: In this example of hormone therapy for prostate cancer, decreased physician reimbursement was associated with a reduction in overtreatment without a reduction in needed services.

Figure 1

Flowchart describing initial dataset and exclusions leading to final cohort.

Figure 2

Proportion of all metastatic (indicated) and low-risk (non-indicated) prostate cancer patients receiving androgen suppression therapy (AST). The proportion receiving non-indicated AST is presented in two ways: with the cohort being all low-risk patients and, alternatively, only those low-risk patients who received no local therapy (ie, radical prostatectomy or radiotherapy). Plotted against the right hand y-axis is the average Medicare payment for each 1 month of AST. Data are shown over the years 1992–2005 and is limited to those registries continuously reporting data to SEER throughout the study period (ie, excludes those added in 2000).