In light of rising health care costs and the introduction of innovative, yet expensive, pharmaceutical products, health tech- nology assessment (HTA) agencies are seeking robust methods for relative effectiveness assessments (REAs) of drugs in routine clinical practice. The relative effectiveness of an intervention is defined as “[t]he extent to which an intervention does more good than harm, when compared to one or more intervention alter- natives for achieving the desired results and when provided under the routine setting of health care practice (i.e. real-world setting)” .
Conventionally, data on treatment effects for drugs are collected in the context of randomized controlled trials (RCTs), whereby a selected, homogeneous group of patients is ran- domly assigned to either the experimental drug or a comparator (e.g., placebo or active comparator) under highly controlled conditions. This study design is ideal to demonstrate the efficacy of a drug, because of its ability to minimize problems with confounding, information bias, and selection bias.