Harris D, Midkiff K, Gilsenan A, Kellier-Steele N, McSorley D, Andrews EB. Study update for a postmarketing case series study of adult osteosarcoma and teriparatide in the US. Poster presented at the 33rd International Conference on Pharmacoepidemiology & Therapeutic Risk Management (ICPE); August 29, 2017. Montreal, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2017 Aug; 26(Suppl 2):314. Previously presented at the 32nd International Conference on Pharmacoepidemiology & Therapeutic Risk Management (ICPE).

BACKGROUND: The Osteosarcoma Surveillance Study is a 15-year safety surveillance study initiated in 2003 to monitor for a possible association between teriparatide (an osteoporosis treatment) and osteosarcoma (OS). OS occurs at a background incidence rate of approximately 2.5 cases per million per year in US adults aged 40 years or older.

OBJECTIVES: To provide an update for this ongoing study, including preliminary data and descriptive characteristics of adult OS patients.

METHODS: Information from all incident cases of OS is identified through participating cancer registries in the US. Information on prior exposure to medications and possible risk factors is obtained via telephone interview with the patient or their proxy. Exposure information is assessed annually through medical record abstraction for a sample of patients. Interim and future final analyses consist of a standardized incidence ratio (SIR) of the observed to expected number of OS cases with a prior history of teriparatide treatment. The expected number of OS cases is the product of the background incidence rate of OS standardized to the age and sex distributions of teriparatide users, the person-years at risk following first exposure to teriparatide, and the proportion of cases that have been interviewed.

RESULTS: As of September 30, 2016, interviews were completed for 1,031 patients diagnosed with OS between 2003 and 2014; two reports of teriparatide use prior to diagnosis were identified. Given the two observed cases, the SIR is 0.59 (90% CI, 0.11-1.86). The expected number of OS cases among patients treated with teriparatide is 3.38. Demographic characteristics were similar for interviewed and noninterviewed patients and correlation was high between self-reported and chart-recorded exposure information. Mean age of interviewed patients was 61 years, 52% were male, and 84% were white. The prevalence of known risk factors for development of OS among the OS cohort was 19% for history of radiation and 4% for history of Paget’s disease of bone.

CONCLUSIONS: From interim calculations, no signal of an increased risk of OS with teriparatide use has been seen in the first 13 years of this 15-year study.

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