Roughly 2 percent of 8,500 poor heterosexuals living in U.S. cities with high rates of HIV infection tested positive for the virus that causes AIDS, and nearly half of those who were infected said they had never been tested before the study, health officials said on Thursday.
The findings by the U.S. Centers for Disease Control and Prevention underscored the links between poverty and HIV infection in the United States, where up to 44 percent of new infections are clustered in 12 major cities, including Chicago, Washington, D.C., New York and Los Angeles.
"I think the main finding is that place matters," Dr. Jonathan Mermin said in an interview. Mermin is director of the CDC's Division of HIV/AIDS Prevention.
Mermin said for many people living in urban areas where HIV is commonplace, their chance of being exposed to HIV with a new sexual partner is much higher than it would be if they were living in another part of the United States.
"Even with equivalent sexual risk behavior, their actual risk of acquiring HIV is greater," he said.
The study, published in the CDC's Mortality and Morbidity Weekly Report, involved a sampling of nearly 8,500 heterosexuals in 21 cities.
Researchers analyzed 2010 data on heterosexuals in neighborhoods with high concentrations of AIDS patients. They focused on people with low socioeconomic status, which they defined as having an income below the federal poverty level or no more than a high school education. For an individual, the 2013 poverty level is $11.490.
More than 70 percent of participants were African American.
Of those tested, 197, or 2.3 percent, were infected with HIV, with highest rates of infection occurring among blacks, those who reported using crack cocaine and those who exchanged sex for money or drugs.
Education and income also made a difference, with higher infection rates reported among people who did not have a high school diploma or those with annual household incomes of less than $10,000. Infection rates were highest among study participants in the Northeast and South.
Overall, 25.8 percent of the study participants had never been tested for HIV. Of those surveyed who were diagnosed with HIV, 45 percent did not know they had it.
"That is much higher than the 18 percent that we estimate for the nation as a whole," he said.
Mermin said the findings clearly showed the need for HIV prevention efforts directed at this population, as well as efforts that link infected individuals with care.
Prior studies have shown that certain groups of HIV patients - the poor, minorities, women and drug users - tended to have worse outcomes and to die earlier. Programs that help address barriers to care, such as transportation to clinics or providing housing for homeless individuals, can help people live longer and reduce HIV transmission.
Currently, the CDC recommends that doctors who treat patients in high risk communities do regular testing, but often patients report not being tested. In this survey, about two-thirds of the people with HIV who did not know they were infected had seen a healthcare provider in the prior year.
"Certainly, a proportion of those people had HIV at the time they visited the provider, but the provider did not conduct an HIV test," Mermin said.
That may change in the next few months when the U.S. Preventive Services Task Force, an influential panel of doctors and scientists advising the government, is expected to release new guidelines calling for routine HIV screening for all Americans aged 15 to 65.
The panel released draft recommendations in November that are expected to affect the reimbursement of HIV testing, removing one of the barriers to the tests.
Under the Affordable Care Act, insurers are required to cover preventive services that are recommended by the panel.
Nearly 1.2 million people in the United States are infected with HIV, yet 20 to 25 percent of them do not know it.
(Reporting by Julie Steenhuysen; Editing by Peter Cooney, Toni Reinhold)