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Arch Gen Psychiatry. 2009 Apr;66(4):417-21. doi: 10.1001/archgenpsychiatry.2008.536.

Tracing the flow of knowledge: geographic variability in the diffusion of prazosin use for the treatment of posttraumatic stress disorder nationally in the Department of Veterans Affairs.

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  • 1Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA.



Passive diffusion of new medical innovations is an important mechanism by which knowledge transitions from research to clinical practice. Preliminary evidence has emerged about the effectiveness of the alpha(1)-adrenergic blocker prazosin hydrochloride in the treatment of nightmares and hyperarousal among patients with posttraumatic stress disorder (PTSD). This treatment has been neither widely accepted nor the subject of active dissemination efforts, and its efficacy was discovered in a discrete geographic location.


To evaluate the pace and reach of the passive dissemination of a promising technology within a national health care system.


Geographic surveillance data study.


Academic research.


We tracked the use of prazosin in the treatment of patients diagnosed as having PTSD in the Department of Veterans Affairs during fiscal years 2004 (n = 203 414) and 2006 (n = 319 670).


The percentage of patients diagnosed as having PTSD who received a prescription for prazosin.


Whereas 37.6% of patients with PTSD treated within the Veterans Affairs Puget Sound Health Care System, Tacoma, Washington, in 2004 were prescribed prazosin, only 18.2% were treated with prazosin at medical centers up to 499 miles (to convert miles to kilometers, multiply by 1.6) away, 6.7% at centers 500 to 999 miles away, 4.0% at centers 1000 to 2499 miles away, and 1.9% at centers 2500 miles away or farther. Adjusting for patient characteristics, patients with PTSD treated up to 499 miles from Puget Sound were about 49% less likely in 2006 and about 63% less likely in 2004 to be prescribed prazosin than their counterparts treated within Puget Sound, while those who were treated 2500 miles away or farther were about 94% less likely in 2006 and about 97% less likely in 2004 to be treated with prazosin than patients within Puget Sound.


Passive diffusion of a new treatment can be rapid in the immediate area in which it is developed, but the geographic gradient of use seems to be steep and enduring even when cost and organizational barriers are minimal.

[PubMed - indexed for MEDLINE]
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