Distribution of prescription drug exposures in the elderly: description and implications.

Using data from a comprehensive prescription drug benefit program in British Columbia, we studied the distribution of prescription drug expenditures and exposures in the community-dwelling elderly over a 1-year period. Overall, 84% of the population was exposed to at least one prescription drug. The 11% of individuals with the highest level of use accounted for 50% of total drug expenditures. Individuals 65 to 74 years of age were exposed to a median of 2.2 different drugs during the year compared to a median of 3.8 for those 75 years of age and over. Twenty-four percent of the 65- to 74-year-old population were exposed to six or more different drugs during a 1-year period compared to 37% of the 75 years and over population. Central nervous system and cardiovascular drugs were most commonly responsible for multiple drug exposures. Forty-eight percent of the individuals exposed to six or more different drugs received prescriptions from three or more different physicians. In British Columbia, 98% of the elderly receiving six or more different drugs received at least one prescription from a general practitioner or a family practitioner.