Electronic medical records can be used to emulate target trials of sustained treatment strategies

Publication date: Available online 2 December 2017
Source:Journal of Clinical Epidemiology
Author(s): Goodarz Danaei, Luis Alberto García Rodríguez, Oscar Fernández Cantero, Roger W. Logan, Miguel A. Hernán
ObjectiveTo emulate three target trials: single treatment versus no treatment, joint treatment versus no treatment, and head-to-head comparison of two treatments. We explain how to estimate the observational analogs of intention-to-treat and per-protocol effects, using hazard ratios and survival curves. For per-protocol effects, we describe two methods for adherence adjustment via inverse-probability weighting.Study Design and SettingProspective observational study using electronic medical records of individuals aged 55-84 with coronary heart disease from >500 practices in the United Kingdom between 2000-2010.ResultsThe intention-to-treat mortality hazard ratio (95% confidence interval) was 0.90 (0.84, 0.97) for statins versus no treatment, 0.88 (0.73, 1.06) for statins plus antihypertensives versus no treatment, and 0.91 (0.77, 1.06) for atorvastatin versus simvastatin. When censoring non-adherent person-times, the per-protocol mortality hazard ratio was 0.74 (0.64, 0.85) for statins versus no treatment, 0.55 (0.35, 0.87) for statins plus antihypertensives versus no treatment, and 1.13 (0.88, 1.45) for atorvastatin versus simvastatin. We estimated per-protocol hazard ratios for a 5-year treatment using different dose-response marginal structural models, and standardized survival curves for each target trial using intention-to-treat and per-protocol analyses.ConclusionWhen randomized trials are not available or feasible, observational analyses can emulate a variety of target trials.



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