Hibberd and Meadows81 found 85% of the UK doctors they interviewed said they used MIMS (a commercial source) to learn about new drugs, but most used noncommercial sources to find out about efficacy. Similarly, the British doctors in Eaton and Parish’s study82 reported using sales representatives as a source of information about new medicines, but relying on them less to establish whether a medicine was useful and should be prescribed.
In a study of British GPs, by Strickland-Hodge and Jepson83, three commercial sources were rated in the top five sources used to alert respondents of new medicines, but five professional sources were the most popular for providing information to evaluate medicines. GPs who worked alone cited sales representatives as a source of information for evaluating drugs more often than GPs who worked in group practices.
In Peay and Peay’s 1994 paper84 about specialists and high-risk medicines, they found that commercial sources of information played little or no role in the adoption of drugs in the doctor’s primary area of expertise, but suggest that these sources may provide information about new drugs outside this area of expertise.
Manning and Denson85 looked at how US internal medicine specialists first learnt about cimetidine. Their study was performed soon after cimetidine was launched in the USA in 1977. Sales representatives were rated as the sixth or seventh most commonly mentioned source in each stage of learning about cimetidine. However advertisements declined in importance. They were the eighth most common source for first knowledge of the drug, tenth for learning principles of using it, and thirteenth for providing update information.
Parboosingh et al.86 in Canada interviewed specialists attending annual scientific meetings and asked them to identify two or three changes they had made in their clinical practice in the last two years, and the factors involved in these changes. Eighty-one of the 192 changes made were changes in prescribing. Sales representatives were noted as initial sources of information for less than 20% of the changes, and very infrequently noted as precipitating the changes. Like other studies, this suggests that commercial information may be more important in alerting doctors to drugs, and less important in later stages of decisions to adopt new medicines.
Williamson87 draws on literature on risk assessment to examine GP prescribing of new drugs. He concludes that the level of risk which a doctor perceives determines how much external validation he or she requires in order to prescribe the drug. From a small survey, Kleinman claims to show that doctors’ preferred information sources vary with the perceived riskiness of medicines. He argues that sales representatives are the most important source for low-risk drugs, but are less important for higher risk drugs. Both studies are too limited to provide conclusive evidence but their theory deserves more testing and their approach of drawing on other social science literature is one that other researchers should follow.
A US survey of 680 doctors88 found that 9% of doctors rarely or never met with sales representatives. The study suggested that documented evidence of a product’s efficacy and applications was the major factor in doctors’ decisions to switch or increase the frequency of a particular medication. The report of the survey in Pharmaceutical Executive provides no detail about the methods used so the study is hard to evaluate.
In one of the few qualitative studies on promotion, Jones et al.89 interviewed 38 consultants in Birmingham hospitals in the UK, and 56 GPs who regularly referred patients to the teaching hospital. They also monitored the prescribing of specific drugs by the GPs, and in the hospital. They reported that sales representatives were an important source of information for both GPs and specialists. Jones et al. suggest that prescribers were not consistent in their definition of ‘prescribing a new drug’. They were unsure whether this meant adding this drug to their regular prescribing repertoire, or whether it could involve prescribing it only a few times. In addition, GPs were unsure whether to include new medicines that they were prescribing because the hospital had started a patient on them. This suggests definitions need to be very clear in quantitative studies in this area, so that results are consistent.
CONCLUSION: Self reports indicate that promotion is often used as a source of information about new drugs, especially for indications for which the doctor has less expertise.