Factors associated with variations in general practitioner prescribing costs.

In this exploratory study information gathered from 520 patients of eight doctors in a city group practice was analysed to identify the collective and separate contributions of selected patient and doctor factors to script cost variations. Results suggested that variance in cost and item numbers was directly related to diagnosis. A principal diagnosis of hypertension or diabetes/endocrine/hormonal problems, or a multiple of diagnoses was associated most with high cost scripts. Other patient conditions, such as gravity of illness, accounted for a much smaller but still significant variance. Although there were only minor differences between males and females, the older age groups in both sexes were over-represented in the higher item and cost categories. Which doctor the patient saw accounted only for approximately half a percent of the total variance, and this was non-significant. The results indicated that doctor prescribing behaviour was related rationally to patient diagnosis, and suggested that peer review, as practised by these doctors, was operating to reduce both variance between doctor factors and prescribing costs.