A retrospective database analysis to assess the impact of zoledronic acid (ZOL) on skeletal-related events (SREs) in solid tumor cancer and multiple myeloma (MM) patients (pts)

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9518 Background: For cancer pts with malignant bone lesions (BM), SREs including pathologic fracture, spinal cord compression, hypercalcemia of malignancy, and radiotherapy and/or surgery to bone are associated with significant morbidity and mortality and reduced quality of life. ZOL is an IV bisphosphonate (BP) proven to reduce and delay incidence of SREs in several tumor types. This study was designed to assess the benefit of long-term ZOL use in a real-life setting. Methods: Claims-based analysis of commercial and Medicare data from a large US managed care plan and a 45 health-plan database was used to evaluate mortality rates, SRE rates, and time from BM to SREs in pts treated with ZOL, pamidronate (PAM), or no IV BP therapy. Pts older than 18 years with solid tumors (breast, prostate, lung, bladder, or renal cell cancers) or MM and BM diagnosed between Jan 2001 and Dec 2006 were included. Continuous enrollment in the health plan for 6 months before the index date and no prior evidence of BM or IV BP use were required. Pts were followed until they left the care plan, switched therapy, or completed the study period. SRE and mortality rates were assessed. Results: The study sample included 28,415 pts with a mean age of 62.5 ± 12.24 years; approx. 25% were treated with ZOL, 8% with PAM, and 67% with no IV BP. Incidences of first and subsequent SREs were higher in the no IV BP group (incidence rate ratio [IRR] = 2.27; 95% CI = 2.03, 2.53 and IRR = 1.3; 95% CI = 1.24, 1.37, respectively) vs the ZOL/PAM groups. Time to first SRE was delayed by approx. 153 days for ZOL vs no IV BP pts. Overall, pts who had greater persistency with ZOL had lower risks of first SRE compared with no IV BP, the greatest risk reduction being observed in the 12- to 18-month persistency cohort, which experienced > 5-fold risk reduction (IRR = 0.19; 95% CI = 0.11, 0.31). The same persistency cohort also had a 27% lower risk of developing a second SRE (IRR = 0.73; 95% CI = 0.62, 0.86) compared with no IV BP. Conclusions: This study showed that in cancer pts with BM, persistence with ZOL resulted in reduced risk of developing first and subsequent SREs. Pts with longer persistence with ZOL achieved better outcomes. [Table: see text]