METHODS	Randomized , double-blind trial conducted June 1997 through July 1999 at 35 outpatient centers in the United Kingdom ( n = 17 ) , United States ( n = 14 ) , the Netherlands ( n = 2 ) , Sweden ( n = 1 ) , and Belgium ( n = 1 ) involving 434 patients with a clinical diagnosis of CFS ( modified US Centers for Disease Control and Prevention criteria ) .\