In health care, clinical trials are conucted to allow safety and efficacy data to be collected for new drugs or devices. These trials can only take place once satisfactory information has been gathered on the quality of the product and its non-clinical safety, and Health Authority/Ethics Committee approval is granted in the country where the trial is taking place. Depending on the type of product and the stage of its development, clinical trials enrol healthy volunteers and/or patients into small studies initially, followed by larger scale studies in patients that often compare the new product with the currently prescribed treatment. As positive safety data is gathered, the number of patients can be increased. Clinical trials can vary in size from a single centre in a single country to multi-centres in multiple countries. The Health Authority in the USA is called the FDA (Food and Drug Administration) where a new product application is referred to as an Investigational New Drug application. In Europe, applications are assessed by national Health Authorities and are called Clinical Trial Applications for Investigational Medicinal Products, for example the MHRA (Medicines and Healthcare products Regulatory Agency) in the UK or the MPA (Medical Products Agency) in Sweden.