Can access limits on sales representatives to physicians affect clinical prescription decisions? A study of recent events with diabetes and lipid drugs.

The authors explored to what extent important medical decisions by practitioners can be influenced by pharmaceutical representatives and, in particular, whether restricting such access could delay appropriate changes in clinical practice. Medical practices were divided into four categories based on the degree of sales representative access to clinicians: very low, low, medium, and high from a database compiled by ZS Associates called AccessMonitor (Evanston, IL) used extensively by many pharmaceutical companies. Clinical decisions of 58,647 to 72,114 physicians were statistically analyzed using prescription data from IMS Health (Danbury, CT) in three critical areas: an innovative drug for type 2 diabetes (sitagliptin), an older diabetes drug with a new Food and Drug Administration-required black box warning for cardiovascular safety (rosiglitazone), and a combination lipid therapy that had reported negative outcomes in a clinical trial (simvastatin+ezetimbe). For the uptake of the new diabetes agent, the authors found that physicians with very low access to representatives had the lowest adoption of this new therapy and took 1.4 and 4.6 times longer to adopt than physicians in the low- and medium-access restriction categories, respectively. In responding to the black box warning for rosiglitazone, the authors found that physicians with very low access were 4.0 times slower to reduce their use of this treatment than those with low access. Likewise, there was significantly less response in terms of changing prescribing to the negative news with the lipid therapy for physicians in more access-restricted offices. Overall, cardiologists were the most responsive to information changes relative to primary care physicians. These findings emphasize that limiting access to pharmaceutical representatives can have the unintended effect of reducing appropriate responses to negative information about drugs just as much as responses to positive information about innovative drugs.