Purpose of Study
The purpose of this study was to assess the impact of US DTCA on Canadian prescribing rates for three heavily marketed drugsóetanercept, mometasone, and tegaserod.
The authors performed a controlled, quasi-experimental study using interrupted time series analysis and data from a sample of 2700 Canadian pharmacies.
Key Overarching Message
Results suggest that the impact of DTCA is mixed, as it worked over the short-term for one drug and not for others. Previous commentary on the effectiveness of DTCA may have overstated the impact on prescribing. Despite the billions spent on DTCA, such strategies may only have a modest effectóand in some cases, no effect at all.
DTCA appears to have mixed impact on prescribing rates, as drug use did not increase for two of the three drugs studied. Despite being banned, DTCA can influence prescribing across national borders. DTCA increased the use of tegaserod, a drug which was eventually withdrawn owing to safety concerns.