Retrospective analysis of the impact of post-approval drug research on utilization of new medicines in the US

Post-approval research can provide critical information for clinical practice. However, quantitative evidence of its value is lacking. This study aimed to assess the impact of publications of post-approval studies on drug utilization. This was a retrospective analysis of US sales data of drugs approved in 2002/2003, compared with the timing of publications in Pubmed within 5 years of marketing. The primary outcome, dSAMP, was a surrogate measure for the impact on utilization, defined as the difference between the sums of SAMP (Sales Actuals Minus Predicted by linear regression) in the three quarters up to the publication and the three following quarters. Seven hundred and sixty-four publications of 15 products were included. Average dSAMP was US$ 14M (95% CI 7.3–20.7; p = 0.00005), with an increase in SAMP mainly in the second and third quarter after publication. dSAMP was negative for publications in years 0–2, neutral in years 2–4, and positive thereafter. Methodological rigor, geographic distribution, and positive or negative outcome only had limited impact on dSAMP. In conclusion, this was the first study demonstrating an impact of post-approval research on utilization of medicines. One published study led to a relative increase in average sales of US$ 14M. Further research is necessary to elucidate the link between utilization and societal value.