Impact of multi-site clinical trial results on clinical practice: Use of risperidone to treat PTSD nationally in the veterans health administration.

Multi-site randomized effectiveness trials evaluate treatments under real-world conditions. Whether results change practice is under-studied. A 6-month 26-site Veterans Health Administration (VHA) cooperative study published in 2011 compared an oral second-generation antipsychotic, risperidone, to placebo for refractory PTSD with null results. National VHA administrative data compared new starts on risperidone during the 5 years before and after the year of publication. Among the 450,000-841,000 Veterans diagnosed with PTSD annually from 2006 to 2016 the proportion with new starts on risperidone declined every year before and after publication. No evidence of an effect of null study results on VHA clinical practice was observed.