Peay and Peay’s 1984 study¹ found two reasonably clear patterns amongst doctors. Those who reported using journals as important information sources evaluated journals more highly and commercial sources lower than other doctors. Those doctors who reported using commercial sources rated these more highly and journals lower than other doctors. There was a group of about 15% of doctors who consistently and exclusively relied on commercial sources of drug information. Those who cited sales representatives as providing information needed to prescribe medicines were older, and those who cited journals were younger.

Although Linn and Davis’s study⁵⁴ was done in 1969-70, there is no reason to believe that the findings are not still relevant. Linn and Davis found that doctors who preferred to use medical journals as a source of advice had more conservative attitudes in other areas than those who preferred sales representatives or other doctors. The former were less positive about the use of non-medical sources of advice (such as friends and family), and the use of medicines in response to daily social stress.

Amongst the New Zealand doctors surveyed by Thomson et al.²⁰ those who reported peer advice being less readily available reported seeing more sales representatives. Cockerill and Williams²⁴ surveyed Ontario pharmacists and found that 60% of them placed no restrictions on visits from sales representatives. However those who became licensed after 1980 were more likely to have restrictions. Andaleeb and Tallman⁵⁵ surveyed doctors in four teaching hospitals in Pennsylvania and found that doctors who treated a higher volume of patients were more positive towards sales representatives. They were also more likely to think that they provided informational and educational support. This study had a low response rate. Stinson and Mueller⁵⁶ carried out a survey of Alabama health professionals, which included 309 doctors as well as other health professionals. They found that doctors with more years of professional experience reported using sales representatives and unsolicited medical literature more often than others, and that general or family practitioners reported using them more than other specialists.

Evans and Beltramini⁵⁷ found in their survey that respondent GPs were more likely to solicit information about prescription drugs from sales representatives than specialists were, and that older doctors were more likely to use sales representatives for information than younger doctors. Overall the doctors they surveyed preferred non-industry sources of prescription drug information. This study had a low response rate, and response bias was not assessed.

County doctors in Oppenheim et al.’s study⁵⁸ tended to rely more on sales representatives as a source of information on prices, compared to other doctors; county physicians and faculty members had limited knowledge of medicine prices and tended to overestimate them. Miller and Blum also found that doctors had limited knowledge of the price of advertised prescription medicines⁵⁹. This study of doctors attending a continuing medical education event had a low response rate.

Santell et al.⁶⁰ surveyed hospital pharmacy directors and sales directors of pharmaceutical manufacturing firms about the role of sales representatives in hospitals. The response rate was low, particularly for the sales directors. Most sales directors thought that sales representatives met the needs of hospital pharmacists more than 80% of the time, but most hospital pharmacy directors thought they were met less than 61% of the time. There was disagreement both about what services were important and how often they were provided.

Hull and Marshall⁶¹ report on an international study of GPs’ sources of drug information. They claim that sales representatives are seen as very important in Sweden, Finland and Yugoslavia (now Serbia and Montenegro) and not important in the UK and Belgium. There are very low numbers in the study, and no details are given about the selection process, so the results should be viewed with a great deal of caution. However, the study raises the important issue of potentially large national differences in attitudes to promotion, which should be taken into account when designing interventions.

CONCLUSION: Doctors appear to fall into different groups with regard to the most used sources of drug information. The available evidence suggests that those who rely more on information from industry tend to be older, less conservative, see more patients, are generalists rather than specialists, have less access to peer support and more positive attitudes to the use of drugs. The finding that older doctors and general practitioners rely more heavily on commercial sources of information comes from multiple sources but other observations about differences between those using non-industry versus industry sources lack confirmatory evidence from more than one study.