Laboratory Diagnosis of HIV Infection

Predictive Value: Single Screening Test

October 2009

I do wish to stress that if one uses the rapid screening antibody test in a population with low prevalence of HIV infection, such as those with HIV prevalence of <5%, the positive and negative predictive value is related to the prevalence of a particular disease. So, for example, if HIV prevalence is 1% in a population that the laboratory serves, then despite having a good sensitivity and specificity of the test, the positive predictive value (meaning that a positive result indicates true positive) is only 83% indicated in this table. And, in many communities in the United States where the prevalence is 0.1% or less (meaning less than 1 in 1000 has HIV infection), the positive predictive value is only 33%, so it's actually less accurate than a flip of a coin.

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Jump to section:

• Introduction
• HIV Markers During Early Infection
• Assay-Defined HIV Detection Windows and Infection Periods
• Serologic Tests for HIV Infection in US
• Principle of Future Combined HIV Antigen-Antibody ELISAs
• Virology Tests for HIV Infection
• HIV Serologic Screening Algorithm
• HIV Rapid Serology Follow-up Algorithm
• Indeterminate HIV-1 Antibody Western Blot Results
• Rapid HIV Antibody Tests Licensed in US, 2009
• Predictive Value: Single Screening Test
• Rapid HIV Antibody Tests: Clinical Applications
• Follow-Up Testing of Reactive Rapid HIV-1 Antibody Tests Results
• Diagnostic HIV Testing in Infants
• Diagnostic HIV Testing in Infants
• Awareness of Serostatus Among People with HIV and Estimates of Transmission in US
• Reasons for Testing: Late vs. Early Testers
• 2006 US CDC Recommendations: Adults and Adolescents
• 2006 US CDC Recommendations: Adults and Adolescents
• 2006 US CDC Recommendations: Pregnant Women
• 2006 US CDC Recommendations: Pregnant Women
• Summary
• Questions?
• Disclosure