Hi Dean,
Here are some suggestions.
Best wishes, Clive
In 2003, a World Health Organization literature review on the impact of pharmaceutical promotion reported that exposure to promotion may influence doctors’ behaviour in ways such as prescribing less appropriately, prescribing more often and adopting new drugs more quickly. These activities may have a direct impact on patients’ health, for example when physicians are persuaded to use drugs with commercial information that is contrary to scientific literature. X et al. surveyed 85 randomly selected doctors who said that scientific sources are much more important in influencing their prescribing than are commercial sources. However, when questioned about the usefulness of two classes of drugs (cerebral and peripheral vasodilators and propohexene) where the message from the scientific literature was the opposite of that in the commercial literature, the majority of doctors in this group held commercial beliefs about these two classes.
You might want to find another way of saying 'commercial beliefs'. The meaning of that does not seem clear.
Promotion also may reduce the quality of healthcare when physicians are convinced to use new drugs with unproven health benefits. This may lower the usage of older drugs that have been shown in rigorous clinical trials to improve declining health outcomes. A study conducted in the USA to describe antihypertensive medication prescribing patterns for 1992 and 1995 found an association between drug advertising and drug usage. In that study, the use of the newest and most expensive agents (calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors) increased, while the use of diuretics and beta-blockers, the only two classes of antihypertensive drugs known to have a well documented benefit of reducing the risk of heart attack and stroke, declined. This result is contrary to the National Institutes of Health 1993 guidelines for the treatment of hypertension.