Objective: Human immunodeficiency virus (HIV) false positivity is one of the common misdiagnoses in laboratories. Thus, only positive results obtained by confirmatory tests should be considered positive while other types of screening tests should instead be referred to as reactive. This study investigated false HIV positivity via the sociodemographic characteristics of the patient, clinical diagnosis, and the relationship with the drugs used.
Materials and Methods: From January 2017 to October 2018, 25,180 patients were tested for HIV with the fourth-generation antigen/antibody EIA. Reactive test results were sent to the Public Health Institution in Turkey to confirm the test results with immunoblot or polymerase chain reaction.
Results: Of the samples, 23 (0.091%) and 113 (0.44%) were found to be HIV-positive and HIV-negative. Confirmation tests were performed on 136 samples. Consequently, 113 samples were confirmed to be negative and, therefore, considered as false positives. A distributional relationship was found between HIV false positivity and patients hospitalized in clinics of infectious diseases, hematology, and orthopedics (χ2=49.048; p=0.001), and patients diagnosed with neoplasm or soft tissue infection (χ2=51.699; p=0.001). Moreover, the rate of false positivity significantly increased with the use of antibiotics, steroidal/nonsteroidal drugs, immunoglobulin preparations, and antithrombotic drugs.
Conclusion: Since HIV tests used in a low prevalence population are commonly testing low-risk individuals, the reactive tests can lead to false-positive results rather than true-positive. Thus, screening test results alone should not be relied upon for this diagnosis.