Use of services and supplies. Utilization is commonly examined in terms of patterns or rates of use of a single service or type of service such as hospital care, physician visits, prescription drugs. Measurement of utilization of all medical services in combination is usually done in terms of dollar expenditures. Use is expressed in rates per unit of population at risk for a given period such as the number of admissions to the hospital per 1,000 persons over age 65 per year, or the number of visits to a physician per person per year for an annual physical. See also UR , UM.