Accuracy of the recorded data is of paramount importance, particularly because this would be the first attempt to capture data globally and because it is currently impossible to estimate what the data would actually look like globally (ie, there would be nothing to compare with). The diagnosis of all the diseases under the umbrella of the PAH diagnosis as well as their differentiation from the many secondary causes of PH is not only complex but also requires many and often expensive invasive (ie, cardiac catheterization) diagnostic tests. Unfortunately, not all practices, even in the developed countries, consider catheterization a mandatory test for the diagnosis of PAH. In addition, many developing countries might not be able to afford such testing. Obviously, inappropriate diagnosis will completely destroy the validity of this effort. There need to be very clear directions on how the disease is diagnosed, and cardiac catheterization needs to be mandatory. Appropriate catheterization will not only confirm the diagnosis but will also eliminate misdiagnosis of secondary PH conditions (ie, left ventricular diastolic dysfunction). CT scans and pulmonary function tests will be required to exclude other causes. The clinicians entering the data need to be experienced and comply with accepted criteria for entry. At the same time, the accuracy needs to be testable at any point, to strengthen the reliability of the project. Thus, although the patients’ personal data will not be entered in the database, the recording of a patient code, a physician code, and a center code will allow an auditor to trace the data to their origin and the records kept, including cardiac catheterization results. Thus, careful record keeping would also be a part of the database in each center, linked directly to the patient, the physician, and the center code numbers.