Statistical primer: a cost-effectiveness analysis.

Cost-effectiveness analyses (CEAs) of new treatment strategies are increasingly reported. This can be a part of a clinical trial or as a separate study. Governments and healthcare payers frequently require a CEA to decide whether a new treatment strategy will be reimbursed. CEA is a framework to assess the effectiveness and costs of a new treatment strategy (e.g. a drug or intervention) when compared with a reference strategy. Effectiveness is often measured in life-years or quality-adjusted life-years, whereas costs consist of direct costs (the costs of the treatment), induced costs (downstream costs and cost offsets) and indirect costs. In this statistical primer, the rationale for assessing the economic consequences of new therapies is explained, followed by the fundamental concepts of CEAs, the different types of CEAs and an introduction to interpretation of CEAs. Finally, a real-world example of a CEA is discussed, comparing cost-effectiveness of transcatheter versus surgical aortic valve replacement in patients with severe aortic stenosis at intermediate surgical risk.