Jan Ostermann of Duke University in Durham, N.C., and colleagues analyzed data from 146,868 U.S. adults ages 18 to 64 who were interviewed between 2000 and 2005 as part of the National Health Interview Surveys.

Study participants were asked if any HIV risk factors, such as receiving blood clotting factors for hemophilia or using injection drugs, applied to them. They also reported on their HIV testing history and whether they planned on being tested in the next year.

The study, published in the Archives of Internal Medicine, Females, found minorities and individuals who reported greater risks for HIV were more likely to be tested. However, even among those reporting a medium or high risk for HIV, fewer than 25 percent were tested in the previous year.

Among those who reported a lifetime risk factor for HIV, 16 percent fewer received a voluntary HIV test than reported plans to get tested -- compared with a 5.6 percent difference between planned and actual testing among those with no risk factors, Ostermann said.