Screening for HIV: Systematic Review to Update the U.S. Preventive Services Task Force Recommendation [Internet]

Excerpt

Background: A 2005 U.S. Preventive Services Task Force (USPSTF) review found good evidence that HIV screening tests are accurate and that identification of undiagnosed HIV infection and treatment of immunologically advanced disease is associated with substantial clinical benefits. However, it found insufficient evidence to estimate effects of diagnosis and subsequent interventions on transmission risks, or to estimate clinical benefits of antiretroviral treatment in patients with less immunologically advanced disease.

Purpose: To systematically update the 2005 USPSTF review on benefits and harms of screening for HIV infection in adolescents and adults, focusing on research gaps identified in the prior review.

Data Sources: We searched the Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews (through the second quarter of 2012) and Ovid MEDLINE (2004 through June 2012) and manually reviewed reference lists.

Study Selection: We selected randomized trials and observational studies that compared different HIV screening strategies and reported clinical outcomes; the uptake, yield, or harms of screening; CD4 counts at diagnosis; or rates of linkage to care. We also selected randomized trials and observational studies that reported the effects of starting antiretroviral therapy (ART) at different CD4 count thresholds and long-term harms associated with ART, and randomized trials and observational studies that reported the effects of screening and subsequent interventions on risky behaviors and transmission risk.

Data Extraction: One investigator abstracted data and a second investigator checked data abstraction for accuracy. Two investigators independently assessed study quality using methods developed by the USPSTF.

Data Synthesis (Results): No study directly evaluated effects of screening for HIV infection versus no screening on clinical outcomes, or compared effects of repeat screening versus one-time screening. Evidence from studies comparing effects of different HIV screening strategies on the uptake or yield of screening, CD4 count at diagnosis, linkage to care, or harms associated with screening is too limited to draw reliable conclusions. New evidence provides strong evidence for effectiveness of earlier initiation of ART, including a subgroup analysis from a randomized trial that found initiation of ART at CD4 counts <0.250 × 10⁹ cells/L associated with markedly increased risk of death or acquired immunodeficiency syndrome (AIDS) events compared with initiation at CD4 counts >0.350 × 10⁹ cells/L after a mean of 18 months (hazard ratio, 5.3 [95% CI, 1.3 to 9.6]). Large, fair-quality cohort studies also consistently found initiation of ART at CD4 counts of 0.350 to 0.500 × 10⁹ cells/L associated with decreased risk of mortality and clinical events compared with delayed initiation. New evidence from good-quality cohort studies confirm a small increase in risk of long-term cardiovascular events associated with certain antiretroviral drugs. Although direct clinical evidence showing that changes in risky behaviors as a result of screening or subsequent interventions reduces transmission risk remains unavailable, there is now strong evidence from a randomized trial as well as consistent evidence from multiple observational studies that ART use is associated with an approximately 10- to 20-fold reduction in risk of sexual transmission of HIV infection.

Limitations: Only English-language articles were included. Observational studies were included. Studies conducted in resource-poor or high-prevalence settings were included, but might be of limited applicability to general screening in the United States.

Conclusions: Prior studies have shown that HIV screening is accurate, targeted screening misses a substantial proportion of cases, and treatments are effective at improving clinical outcomes in patients with advanced immunodeficiency. New evidence indicates that ART reduces risk of AIDS-defining events and mortality in persons with less advanced immunodeficiency and reduces sexual transmission. More research is needed to understand effects of different screening strategies on the uptake and yield of screening, harms, CD4 count at diagnosis, and linkage to care.