The UK Drug Safety Research Unit has discovered massive variations in the quantity of drugs prescribed by individual doctors (The Lancet, 11 September 1993). The differences suggest that some doctors may be influenced less by their patients' condition and more by the promotional activities of drug companies.

Researchers looked at the prescribing patterns for 27 new drugs among 28,402 GPs. They concluded: '10 per cent of doctors who had prescribed most heavily accounted for 42 per cent of total prescribing.' One doctor prescribed the heart drug betaxolol so heavily that he alone accounted 'for 3.4 per cent of the total use of that drug in England during the period covered by the study.'

The researchers also concluded that the heaviest prescribers were the least conscientious in recording any side effects suffered by their patients. Overall, 53 per cent of doctors responded to requests for this information, 'but the heaviest 10 per cent of prescribers returned only 44 per cent and the heaviest 1 per cent returned only 34 per cent of questionnaires', the study reported.

Most damning was the report's conclusion that the surveillance of side effects following the launch of any new drug was being 'exploited by the pharmaceutical industry as a means of increasing sales. 'Schemes are set up which are, at best, uncontrolled postmarketing clinical trials or, more often, marketing exercises intended to create product awareness.' In some of these 'studies', doctors are paid for each patient they put on a particular drug.

The researchers conclude: 'It is not possible that the medical needs of patients in different practices could vary so much that 42 per cent of the need should be concentrated in the practices of 10 per cent of doctors.'