Inexpensive Test That Measures Levels of HIV Protein Equally Effective as Current Tests in Predicting Disease Progression, Study Says

A "relatively inexpensive" experimental test that detects levels of an HIV protein in the blood could be used to predict how soon a person with HIV will develop AIDS and to track disease progression, according to a study in the Oct. 15 issue of the Journal of Infectious Diseases, Reuters Health reports. There are currently two tests that are used to track early-stage HIV progression; one measures levels of a patient's CD4+ T cells and the other measures a patient's viral load (McKinney, Reuters Health, 10/21). These tests help providers determine when to initiate highly active antiretroviral therapy and monitor the effectiveness of treatment, but they are not widely used in developing countries because of their high cost (Sterling et al., Journal of Infectious Diseases, 10/15). Dr. Timothy Sterling of the Johns Hopkins University School of Medicine and colleagues compared the effectiveness of a new test that measures levels of an HIV protein called p24 antigen with the CD4+ T cell and viral load tests (Reuters Health, 10/21). Although the p24 antigen test has been used for tracking disease progression among people with advanced stages of HIV infection, it has not been analyzed for effectiveness among people with early-stage disease (Journal of Infectious Diseases, 10/15). The three tests were used among 494 injection drug users who had recently contracted HIV. The study states that over the course of five years, the p24 antigen test was "comparable to the other tests at predicting AIDS progression" (Reuters Health, 10/21). Sterling said that the p24 antigen test could either be used alone or in conjunction with the CD4+ T cell and viral load tests (Johns Hopkins Bloomberg School of Public Health release, 10/16).

Antigen Test Less Costly
Sterling said that the accuracy and low cost of the antigen test could make it particularly useful in developing nations. At Johns Hopkins, a CD4+ T cell test costs $88 and a viral load test costs $152, while a p24 antigen tests costs between $20 and $30 (Reuters Health, 10/21). The researchers said that because patients must be tested often to monitor disease progression, the antigen test would ultimately prove much more affordable than the other tests. They added that the antigen test is also easier to store and use than the other tests (Johns Hopkins Bloomberg School of Public Health release, 10/16). But Sterling warned that the test must also be studied in developing nations to determine whether it is as effective at monitoring the strains of HIV most commonly found in those regions (Reuters Health, 10/21).