What is considered a positive PPD test at 5 millimeters for which population?

A positive PPD test, or tuberculin skin test, at 5 millimeters is considered significant in populations with a high risk for tuberculosis (TB infection). Confirmed or suspected HIV infection is one of the groups that are at an elevated risk. Individuals with HIV have a compromised immune system, making them more susceptible to latent TB infection progressing to active disease. Therefore, a reaction of 5 millimeters or more is significant in this population because it indicates a higher likelihood of infection that may require immediate further evaluation or treatment.

For the other populations mentioned, the thresholds for a positive PPD test vary. Occupants of long-term care facilities, healthcare workers without risk factors, and those over the age of 65 generally require a larger induration measurement (typically 10 millimeters) to be considered positive due to their respective lower risk profiles. In summary, the 5 millimeter threshold aligns specifically with the heightened risk factors present in individuals with HIV, warranting cautious monitoring and intervention strategies for TB infection in this vulnerable group.