Real-world studies no substitute for RCTs in establishing efficacy

[...]rapid increases in the availability of registries, electronic health records, and insurance claims, and the ability to access, process, link, and analyse data from these sources at fairly low cost lend support for calls to replace randomised controlled trials (RCTs) with so-called real-world studies to establish the efficacy of a therapy,1,2 particularly for common serious diseases with abundant, easily collected data such as diabetes.3 This push is driven partly by the need to show payers that therapies are working and are therefore of value when used in the real world.4 Other driving factors include the industry's wish to reduce costs and time to get results, a mistaken belief that real-world data are somehow more relevant than RCT data for establishing efficacy, and the ease and speed with which registry data can be accessed and publications generated. When the effects of insulin on mortality in the observational study described above were evaluated in a large RCT, the effect of insulin on the risk of death was neutral.9 Thus, apparently clear findings based on observational data from the real world were not corroborated when the possibility of confounding was removed by randomisation. [...]they are robust for the assessment of the efficacy of a therapy and to produce the clear, unbiased, and least confounded evidence needed to inform clinical care.