Generalizing Randomized Clinical Trial Results: Implementation and Challenges Related to Missing Data in the Target Population

Abstract Statins are indicated in patients with elevated levels of high-sensitivity C-reactive protein and normal low-density lipoprotein cholesterol based on results of the multicountry trial, Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) (2003–2008), but the benefit in real-world populations remains unknown. We sought to generalize JUPITER results to trial-eligible population using data from the UK Clinical Practice Research Datalink (CPRD), 2001–2014. We multiply imputed missing baseline characteristics for the CPRD population and selected the trial-eligible participants as the target population based on observed and imputed values. Trial participants were weighted to be representative of the CPRD population (n = 383,418) based on individual predicted probability of selection into the trial. Trial participants were also standardized to the CPRD population without missing values (n = 2,677). In JUPITER, rosuvastatin reduced cardiovascular risk with a 3-year risk difference of −2.0% (95% confidence interval (CI): −2.9, −1.1). The rosuvastatin effect was muted in the first 2 years but remained strong at 3 years after standardizing to the imputed CPRD population (3-year risk difference = −2.7%; 95% CI: −5.8, 0.4) and the CPRD population without missing data (3-year risk difference = −1.7%; 95% CI: −3.5, 0.1). The study serves as an illustration of possible approaches to understanding generalizability of trials using real-world databases given limitations due to missing data on inclusion/exclusion criteria.