Comparison of prescribing unit with index including both age and sex in assessing general practice prescribing costs

Abstract

Objective: To examine and compare the prescribing unit and a new prescribing index adjusting for age and sex in assessing general practice prescribing.

Design: Analysis of all prescriptions issued by two practices in one year. Use of data to derive a prescribing index adjusting for age and sex. Comparison of effect of prescribing unit and new index on relation between 80 practices' prescribing data and family health services authority average.

Setting: Newcastle and Gateshead Family Health Services Authorities. Two urban practices with eight doctors and combined list size of 16,300 patients.

Main outcome measures: Cost and number of prescriptions issued to each age and sex group. Effect of index on relation between practice data and family health services authority average.

Results: The number of items prescribed and total costs rose with age. Although total costs were greater for women than for men, individual items cost more for men aged 25-84. Comparison of data adjusted by the prescribing unit and the new index with authority averages produced no significant differences except in a few practices with skewed age-sex demography. Results with the two indexes differed by over 5% in 34% (27/80) of practices for costs and in 14% (11/80) for items prescribed.

Conclusions: The age and sex profile of a practice does not explain interpractice variation in prescribing patterns. Other unidentified factors need to be considered.