Medical availability and clinical practice vary worldwide due to regional differences. Culture, technology, and modern scientific medicine are highly developed in the Western world, while in developing countries such as parts of Africa or Asia, the population may be more dependent on it. Relying on traditional medicine with limited evidence and efficacy and no formal training required for practitioners. For example, a 2007 review of the literature found that about 49% of interventions lacked sufficient evidence to support benefits or harms. In modern clinical practice, physicians and physician assistants personally assess patients, diagnose, predict, treat, and prevent disease using clinical judgment. The doctor-patient relationship usually begins with an interaction with the patient's examination, medical history and medical record, followed by a medical interview and physical examination, and initial diagnosis with medical equipment (eg, medical phone) is usually used.