(1) A physician whose professional activities are performed chiefly within a hospital, e.g., anesthesiologists, emergency department physicians, intensivists (intensive care specialists), pathologists, and radiologists. SYN: hospital-based physician. (2) A primary care physician (not a house officer) who assumes responsibility for the observation and treatment of hospitalized patients and returns them to the care of their private physicians when they are discharged from the hospital. [hospital + -ist]The hospitalists professional society, The National Association of Inpatient Physicians (NAIP), has defined hospitalist as a physician whose primary professional focus (clinical, teaching, research, or administration) is general inpatient care. A hospitalist may be an employee of a hospital or HMO, a contractor, or a private practitioner. About 75% of hospitalists are general internists. Hospital-based primary care physicians free general practitioners from the need to make daily rounds to visit hospitalized patients. Several studies have shown significant decreases in hospital costs and in length of hospital stays under the hospitalist system, with no decline in quality of care or patient satisfaction. Some academic medical centers have adopted hospitalist models for inpatient care and teaching.