Use utilization is commonly examined in terms of patterns or rates of use of a single service or type of service, e.g., 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, e.g., number of admissions to hospital per 1 ,000 persons over 65 per year, or number of visits to a physician per person per year for family planning services.