Relationship between the number of partners in a general practice and the number of different drugs prescribed by that practice.

The objective of this study was to assess whether practice size, as measured by the number of doctors, had any bearing on the range of drugs prescribed. All practices in the northern and western health boards in Northern Ireland were included in the study--a total of 132 practices (362 doctors) serving a population of 628,249. Prescribing data, obtained from the Department of Health and Social Services (Northern Ireland) information technology unit database, were analysed retrospectively for the month of January 1989. The number of different preparations prescribed in each of 22 therapeutic groups were counted. Hence a measure of the range of prescribing was assessed. A significant correlation was found between the number of different preparations prescribed and the number of general practitioners working in the practice. However, no correlation was found between the number of different drugs prescribed and the mean prescribing cost per patient or the mean list size of the doctors in each practice. The use of a practice prescribing policy was found to have no influence on the range of drugs prescribed, nor on the prescribing costs. The inference is that formal therapeutic policies may be difficult to implement within group practices. These results are of importance to general practitioners since the greater the number of different drugs prescribed the greater will be the risk of side effects and dangerous interactions.