Aims: We assessed the suitability of real-world data (RWD) as an external control for analysis of overall survival (OS) compared with clinical trial data (CTD) in advanced melanoma. Methods: OS among adults receiving ipilimumab for advanced melanoma was compared between trials (CTD group) and the Flatiron Health database (RWD group) using Cox models. Adjusted analyses accounted for differences in baseline factors; missing data were addressed through multiple imputation. Results: After adjusting for baseline factors and accounting for missingness, OS was similar in the CTD (n = 241) versus RWD groups (n = 816; hazard ratio: 0.98; 95% CI: 0.75-1.26). Conclusion: Flatiron Health data is suitable to construct external control groups for OS in advanced melanoma trials after adjusting for baseline factors and missing data.
Keywords: clinical trial data; external control; melanoma; methods; real-world data; survival.
Clinical trials are the gold standard for measuring the efficacy and safety of new treatments. Comparisons between clinical trials and external controls drawn from real-world data are potentially valuable – especially when randomized trials are not available or feasible – but carry important risks of bias stemming from differences across populations, care settings and measurement of patient characteristics and outcomes. As a case study, we assessed the suitability of a particular real-world database (the Flatiron Health Database) for analyzing overall survival among patients in clinical trials of treatments for metastatic melanoma. Challenges included differences in patient baseline prognostic factors across populations, including high proportions with missing information in real-world data. After accounting for these differences, we observed similar survival between patients receiving ipilimumab monotherapy in clinical trials and in real-world data. We conclude that real-world external controls can be suitable for metastatic melanoma.