With rare exceptions, research shows that information provided directly by drugmakers to doctors is linked to higher prescribing frequency, increased costs or lower prescribing quality, says a new study.

A new meta-analysis of 58 studies finds no evidence of net improvements in prescribing resulting from such exposure. While the researchers do not exclude this possibility, they recommend that prescribers should “follow the precautionary principle and thus avoid exposure to information from pharmaceutical companies,” reporting their findings this morning in the US Public Library of Science journal PLoS Medicine.

10 of the 58 studies examined the effects on prescribing quality, and all but one of these suggest that exposure to drug company information is associated with lower prescribing quality, or detect no association, say the researchers, led by Geoffrey Spurling of the University of Queensland, Australia.

17 out of 29 studies which looked at the effect of pharmaceutical sales representatives' visits found an association between visits and increased prescribing, with none finding an association with less-frequent prescribing. And seven out eight studies examining the relationship between exposure to drugmakers’ information and prescribing costs indicated that such exposure was associated with higher costs, or no association was detected.

“So, for example, one study found that physicians with low prescribing costs were more likely to have rarely or never read promotional mail or journal advertisements from pharmaceutical companies than physicians with high prescribing costs,” the authors comment.

“The pharmaceutical industry claims that drug promotion helps to inform and educate healthcare professionals about the risks and benefits of their products and thereby ensures that patients receive the best possible care,” say the researchers. They add that, in theory, advertising may be beneficial in several ways - by distributing information and thus improving the quality of prescribing, by increasing prescribing of drugs that provide better health outcomes or by improving the cost-effective use of healthcare resources.

However, while their research does not disprove these theories, it finds little evidence to support them and, indeed, reveals evidence of higher costs and lower quality of prescribing, they note.

“In the absence of evidence of net improvement in prescribing from exposure to promotional information, we recommend that practitioners follow the precautionary principle and thus avoid exposure to information from pharmaceutical companies unless evidence of net benefit emerges,” the researchers conclude.

- Meantime, an investigation by US news groups has reported that “hundreds” of doctors used by pharmaceutical companies as promotional speakers or consultants have been accused of misconduct, disciplined by state boards or lack credentials as researchers or specialists.

The probe, by investigative journalism group ProPublica and five news organizations, reports that drugmakers have paid some 17,700 healthcare providers (mainly doctors) a total of $257.8 million since 2009 for promotional and consultancy work. Two physicians have received more than $300,000 from one or more drugmakers during this time, 43 have been paid over $200,000 each and 384 have received over $100,000, it says.

Over 250 of these experts, “including some of the highest-paid speakers,” have been citied for professional misconduct, with some even losing their licenses before becoming drug company speakers, reports National Public Radio (NPR), one of the five news groups.

Another, the Boston Globe, reveals that more than 40 of the paid experts have received warnings from the Food and Drug Administration (FDA) for research misconduct, have lost hospital privileges or “been found guilty of crimes,” while “at least 20 more have been the target of two or more malpractice lawsuits.”

The other news groups involved in the investigation are the Chicago Tribune, Consumer Reports and PBS’ Nightly Business Report.