OBJECTIVES: As US health care increasingly looks towards proven clinical effectiveness for reimbursement decisions, we hypothesized that HTAs published by NICE would influence drug prescribing and patient cost-sharing expenditures in the US according to the nature of the published guidance. The primary objective was to determine whether trends in prescription volume (TRx) and the proportion of drug costs paid out-of-pocket (%OPC) of 10 drugs appraised by 7 HTAs since 2007.  METHODS: Seven NICE HTAs since 2007, evaluating a total of 10 drugs, were analyzed.  Six drugs were freely encouraged for utilization (lenalidomide, entecavir, tenofovir, donezepil, galantamine, rivastigmine), two were approved for restricted populations (cinacalcet, naltrexone) and the use of two of the drugs was restricted for all populations (telbivudine, memantine).  TRx, and OPC as a percent of average retail price were collected quarterly for the same duration pre- and post-HTA until April 2010 using SDI’s VONA and VOPA databases. Statistical analyses were performed using one-way ANOVA; statistically significant results had p<0.05. RESULTS: Comparing the periods before and after HTA publication, three drugs with positive guidance showed significant increases in prescription volume (p<0.05).  However, two drugs with advised use for restricted populations, and one with a negative guidance also showed significant increases.  Interestingly, two drugs with positive guidance showed significant decreases in TRx.  Only entecavir showed a significant decrease in %OPC, while all others failed to show a significant difference.  CONCLUSIONS: NICE HTAs decisions appear to be associated with mixed effects on prescription utilization and expenditures in the US. Though prescribing behavior was changed in the periods analyzed, further research is warranted to determine the true nature of that change.  With increased cost-sharing in the healthcare environment in the US, it will be interesting to monitor the forces that might precipitate changes in OPC, whether related to HTA publications or not.