The Centers for Disease Control and Prevention (CDC) released new recommendations in 2006 for human immunodeficiency virus (HIV) testing.¹ These far-reaching recommendations are a major revision from the CDC's previous guidelines. They aim to reduce the number of people with undiagnosed HIV infection in the United States (estimated to be one fourth of the 1.0 to 1.2 million persons living with HIV, or 252,000 to 312,000 persons²) and to reduce the stigma and barriers associated with testing. The guidelines represent a policy shift from testing only persons at high risk for HIV infection to universal testing for adolescents and adults. The CDC now recommends that all persons 13 to 64 years of age in all health care settings be tested for HIV after the patient is notified that testing will be performed unless he or she declines (i.e., opt-out screening). Table 1 presents a summary of key recommendations.¹

The recommendations are based on changing HIV epidemiology, results from universal blood and prenatal screening programs, and expert opinion. About 40,000 persons are newly infected with HIV each year in the United States.³ This number has been stable over the past decade, but an increasing number of blacks and other racial and ethnic minorities are being infected. Increasing proportions of infected persons are adolescent males who have sex with males; women now make up 30 percent of newly diagnosed cases.^4,5 Only about 40 percent of U.S. adults have been tested for HIV.⁶ Strikingly, the number of infants and children with newly diagnosed acquired immunodeficiency syndrome (AIDS) from perinatal transmission peaked at 945 in 1992 and fell to 48 in 2004 as the result of widespread prenatal testing.⁷

About 40 percent of persons with newly diagnosed HIV infection develop AIDS within one year.⁷ This statistic suggests that there are missed opportunities for diagnosis. The transmission rate is estimated to be 3.5 times higher among persons who are unaware of their infection, and early treatment with highly active anti-retroviral therapy decreases the risk of transmission and prolongs life. Therefore, it is estimated that new sexually transmitted HIV infections could be reduced by more than 30 percent if all persons infected with HIV knew their status and adopted behavior changes similar to those of persons who are aware of their infection.⁸

Other professional groups have also made recommendations for screening. In 2001, the Institute of Medicine recommended an opt-out approach to HIV testing and recommended eliminating written consent and extensive pretest counseling.⁵ In 2005, the U.S. Preventive Services Task Force (USPSTF) recommended HIV testing for high-risk persons and pregnant women (Level A recommendation).³ However, it made no recommendation for or against routinely screening adults and adolescents who are not at increased risk (Level C recommendation).⁹ The USPSTF recently reaffirmed this recommendation for nonpregnant adolescents and adults.¹⁰ The policy of the American Academy of Family Physicians (AAFP) echoes that of the USPSTF; the AAFP has not yet taken a position on the new CDC recommendations.

Finding the persons who do not know they are HIV positive will not be easy. There are many barriers to implementing universal screening. In light of competing health care prevention priorities, many physicians think the benefits may not outweigh the time and resources required to implement this recommendation. The prevalence of undiagnosed infections in primary care practices is unknown. In a low-prevalence population, false-positive or indeterminate results will take time to explain and follow up. Universal screening is an unfunded mandate in settings where patients are uninsured or where insurers reimburse less than costs. Follow-up services for persons who test positive may not be known or available. Despite the CDC recommendation, many states require time-consuming written consent and pretest counseling. Blood is not routinely drawn in most patients until they are in their 30s, making testing of young adults more difficult as part of regular care. Physicians still will not be able to test persons who do not seek medical care or who have difficulty accessing the health care system.

Unrecognized infections are likely more common in certain settings (e.g., emergency departments, sexually transmitted disease [STD] clinics, correctional facilities, substance abuse programs). Undiagnosed HIV infection also may be more prevalent in other settings, such as hospital inpatient services, community health centers, and urgent care centers. Routine HIV screening in emergency departments, hospitals, and STD clinics has found HIV prevalence rates of 2 to 7 percent.¹¹

In summary, the new CDC recommendations aim to close many of the loopholes in testing and will help remove the stigma associated with testing and simplify testing procedures. However, the USPSTF took a more conservative approach, concluding that the benefit of screening adults without risk factors for HIV infection is too small to justify a general screening recommendation. I believe we should proceed by implementing universal testing in certain settings where there is likely a higher prevalence of undiagnosed HIV infection, such as in emergency departments and STD clinics. If rapid testing is used, patients can get results quickly, and fewer will be lost to follow-up. A recent report from South Carolina found that three fourths of persons who were diagnosed with HIV infection late in the disease course had visited a health care facility within the previous few years; 79 percent of these persons had visited an emergency department, and 12 percent were inpatients.¹² This suggests that we would gain the most if HIV testing were increased in emergency departments. To reconcile the CDC and USPSTF recommendations, we should continue to test high-risk persons, work to decrease legislative and financial barriers to testing, and first expand universal testing to clinical sites where the prevalence is likely to be high.