RESULTS	Respondents who had a primary care physician ( odds ratio [ OR ] , 2.0 ; 95 % confidence interval [ CI ] , 1.3-3 .2 ) , were more knowledgeable about advance directives ( OR , 2.0 ; 95 % CI , 1.4-2 .9 ) , or had seen a friend or family member use a mechanical ventilator ( OR , 1.5 ; 95 % CI , 1.02-2 .1 ) were significantly more likely to have designated a health care proxy .\