The majority of newly released prescription drugs target morbidities experienced by older patients, and it is older patients who are at increasing risk of experiencing an adverse drug event after being prescribed a newly released drug. The majority of new drugs are prescribed to older patients as soon as they are given regulatory approval to market. The important concern for older patients is that clinical trials of these new drugs frequently exclude participants who have co-morbidities commonly existing in older age groups, as well as excluding co-medications that are commonly taken by older patients. This book examines a method for early identification of risk factors to offset clinical trial findings with limited applicability to older patients. The method uses linked de-identified administrative health data to develop a profile of the receiving population for a newly approved drug. This patient profile can then be compared with the exclusion protocols applied in the clinical trials of that newly approved drug to support prospective identification of patient groups potentially at risk if they are prescribed that drug in the context of their co-morbidities and co-medications.