USING HEALTH CARE ADMINISTRATIVE DATA TO ESTIMATE COSTS FOR ANDROGEN DEPRIVATION THERAPY IN PROSTATE CANCER PATIENTS

Purpose:

To estimate and compare real-world total health care costs for clinically relevant androgen deprivation therapy (ADT) regimens and indications for prostate cancer (PC).

Method:

Using a cancer registry and health care administrative databases in the province of Ontario, Canada, PC patients who started >90 days of ADT at age >66 in 1995 to 2005 were selected and classified by ADT regimen and indication. We used an outpatient prescription drugs database and hospital records to determine ADT regimen: medical castration; orchiectomy; anti-androgen monotherapy; combined androgen blockade (CAB) medical (medical castration plus anti-androgen); CAB surgical (orchiectomy plus anti-androgen). We used prescription drug data, hospital procedure codes, and diagnostic codes to determine indications for ADT: neoadjuvant, adjuvant, metastatic disease, biochemical recurrence, primary (non-metastatic). Using nonparametric regression methods we computed first-year, five-year, and ten-year longitudinal total direct medical costs (CAD2009).

Result:

The cohort numbered 21,818 (mean age 75 years; 54% alive on December 31, 2007). Mean first-year costs were highest among metastatic patients: from $24,403 for orchiectomy to $32,221 for anti-androgen monotherapy. Mean first-year costs for all other regimens and indications were below $20,000 except for medical castration for recurrence ($24,716). Primary treatment with orchiectomy was the least costly ($14,218). CAB medical was the most costly regimen in the first year for primary, neo-adjuvant, and adjuvant indications. Mean five-year and ten-year costs were lowest for neo-adjuvant treatment, with differences of <$3,000 between regimens. Orchiectomy regimens were the least costly, but limited to primary and metastatic indications. CAB Medical was generally more costly than anti-androgen monotherapy or medical castration alone. Annual costs were highest in the first year of ADT, likely due to drug/orchiectomy and costs associated with indication (radiation, metastases, recurrence). Outpatient drugs, including pharmacological ADT, accounted for 17% to 65% of total first-year costs.

Conclusion:

Surgical castration, if clinically relevant, represents considerable cost savings over pharmacological ADT. Monotherapies are more economical than CAB. Metastatic disease is the most costly indication. Administrative data allow estimation of costs in large population-based cohorts over long periods of time. Their lack of detailed clinical data can be overcome by developing algorithms, eg. for treatment regimens and indications. Our real-world costs provide high quality data for PC cost-effectiveness and decision models.