Thirty to 40 percent of people with HIV fail to either enter or stay in care after their initial diagnosis, according to a study published in the November 13 issue of AIDS. These data have implications for the potential success of “test-and-treat” strategies—whereby everyone is tested for HIV and those who are positive receive immediate HIV treatment in an effort to prevent ongoing transmission.

Numerous studies published since the beginning of the HIV epidemic have looked at the percentage of people who enter into HIV care after a diagnosis and who stay in care over time. Unfortunately, the results of these studies have varied widely, as have their methods for measuring these outcomes.

Accurately measuring both factors will be vital to understanding how well test and treat strategies will work. This is because such strategies depend on getting people with HIV in care and ensuring that they have an undetectable viral load. The hypothesis is that if viral loads across a given population can be lowered to undetectable levels, then that population will be less infectious.

In an effort to better assess the likelihood of entry or retention in care since the introduction of potent combination antiretroviral (ARV) therapy, Gary Marks, PhD, and his colleagues from the Centers for Disease and Control and Prevention (CDC) in Atlanta combined the results of about 50 studies published between 1996 and 2009. Since four of the studies included data on both entry into care and retention in care, the authors refer to data on these variables as “findings” rather than “studies.”

In terms of entry into care, 26 studies contributed 28 findings involving 53,323 people with HIV. To assess trends in HIV care retention, Marks and his colleagues split the findings into those that collected data before 2003 (12 findings) and those that collected data between 2003 and 2009 (16 findings). The team also broke up the findings based on the length of time between HIV diagnosis and entry into care (four, six or 12 months). Lastly, participants were split up into two groups based on where they received their HIV test results: an emergency or urgent care setting, or a community based organization or clinic.

Overall, between 66 and 71 percent of people studied entered into HIV care after a diagnosis, though results varied widely over the different findings. Entry into care was higher in findings from 2003 or later than in findings from before 2003. Entry into care did not differ significantly depending on the number of months after a person first tested positive. People were as likely to enter care within four months of a diagnosis as they were to enter care within one year of diagnosis. A higher percentage, 76 percent, entered into care after testing in an emergency room than those who tested in a community-based setting—just 67 percent.

Though the authors state that significant improvements are needed in getting people to enter care after a diagnosis, they noted that care entry appears to be improving over time—results which they characterized as “encouraging.”

In terms of retention in care, the results were not as promising. Marks’s group looked at 28 studies with 28 findings, which included a total of 75,655 people. Retention was measured as multiple visits over the study period, and the study periods varied from six months to five years.

Most of the studies available measured retention before 2003, and no studies covered any period after 2006. Overall, 59 percent of people across the studies were retained in care, but results varied across the studies. Care retention was higher before 2003 (62 percent) than after 2003 (42 percent). The authors caution that this doesn’t necessarily mean that care retention is diminishing over time, as only four studies were available for analysis from the period from 2003 to 2006, and none reported results from between 2006 and 2009.

Nevertheless, care retention varied a great deal depending on the length of time that people were followed, and these results are discouraging. Roughly 60 percent of people were retained over the first two years of follow-up, compared with just 41 percent over periods longer than three years. Fortunately, retention did not vary by the population studied. Drug users and those with mental illnesses were as likely to be retained in care as those in the general population of people with HIV.

The authors note that a number of strategies have proved that entry into care can be significantly improved if linkage coordinators are employed to address people’s barriers to entering care. However, the researchers also stated: “Improving retention in care may be more challenging.”

This is because some of the reasons that people leave care are not easy to modify or address, especially issues related to drug use, incarceration and unstable housing. Further studies on the best methods for care retention are needed, said Marks and his colleagues.

However, both entry and retention in care will be vital for test-and-treat efforts to significantly lower HIV transmission in the United States. For test-and-treat to be really successful, we must do a better job getting people who test positive linked to a provider and keeping them in care once they are linked up.

They conclude: “Our findings provide baseline estimates for entry and retention in care and indicate that there is considerable room for improvement in these parameters.”