This book explores the comparative effectiveness of medical treatments as applied in the health care sector. An analysis of comparative effectiveness is simply a comparison of the impact of different options that are available for treating a given medical condition for a particular set of patients. These studies may compare both similar treatments, such as competing drugs, or they may analyse very different approaches, such as surgery and drug therapy. The analysis may focus only on the relative medical benefits and risks of each option, or it may go on to weigh both the costs and the benefits of those options. In some cases, a given treatment may be found more effective for all types of patients, but more commonly a key issue is determining which specific types would benefit most from it. Although some information about the effectiveness of new drugs, medical devices, or procedures is often available, rigorous comparisons of different treatment options are less common. Thus, this book compares and discusses which treatments work best for which patients and whether the added benefits of more-effective but more-expensive services are sufficient to warrant their added costs.