Effects of radium-223 dichloride (Ra-223) on risk for hospitalization and health care resource use in the phase 3 ALSYMPCA trial.

Abstract

21 Background: Ra-223 is a first-in-class alpha-emitter approved for treatment (tx) of patients (pts) with castration-resistant prostate cancer and symptomatic bone metastases. In ALSYMPCA, Ra-223 significantly improved overall survival by 3.6 months vs placebo (pbo) (HR = 0.70; 95% CI, 0.58-0.83; P < 0.001) and was well tolerated. To understand whether the tx benefit corresponds to differences in utilization, hospitalization and other types of health care resource use were evaluated. Methods: Data on hospitalization, nursing home visits, home health care and adult day care services use, and physician visits were captured for each pt. Tx groups were compared, based on percentage needing each type of health care resource, using Fisher’s exact test. To account for differences in each pt resource use in ALSYMPCA, the number of encounters (eg, office visits) and duration of encounters (eg, days hospitalized) were divided by observation time. The mean number and duration of encounters were compared using analysis of variance. To compare tx groups based on the rate of use per year, incidence rates and ratios were calculated using a generalized estimating equation (GEE) regression model. Results: The mean follow-up time in months for Ra-223 vs pbo was 10.0 vs 8.6. The incidence rate for Ra-223 vs pbo was 1.1 vs 1.4 (incidence rate ratio = 0.77; 95% CI, 0.62-0.95; P = 0.013). The mean number of hospitalizations and hospitalization days per year for Ra-223 vs pbo were 1.3 vs 1.7 (P = 0.020) and 8.1 vs 14.6 (P < 0.001), respectively. The percentage of pts that required hospitalization was nominally lower for Ra-223 vs pbo (42.3% vs 49.0%, P = 0.062). Among pts who experienced at least one hospitalization, the mean number of hospitalization days per year for Ra-223 vs pbo pts was 19.4 vs 30.4 (P < 0.001). No significant differences were found between tx groups in terms of visits or durations of time in nursing homes per year, amount of adult day care and home health care services utilized per year, and number of physician visits per year. Conclusions: Compared with pbo, Ra-223 tx resulted in a 23% reduction in incidence of hospitalizations per year and about 6.5 fewer hospitalization days per pt per year. Clinical trial information: NCT00699751.