Confirmatory test results in patients with a reactive anti-HIV test result: four-year data

Abstract

Objective: The aim of this study was to evaluate the results of confirmatory tests performed by line immunoassay (LIA) in blood donors and patients with suspected HIV infection, and patients undergoing preoperative or antenatal screening, of whom anti-HIV-1/2 test results were found as repeatedly reactive. Methods: Serum samples sent to the microbiology laboratory between January 2014 and December 2017, were tested by the fourth-generation enzyme-linked immunosorbent assay (ELISA), which identifies the anti-HIV-1/2 antibodies and p24 antigen together. The repeatedly reactive samples were investigated by LIA method as a confirmatory test. Results: A total of 106 786 patients’sera were screened by ELISA. Of these patients, 47 723 (45%) were male and 59 063 (55%) were female. The distribution included 37 375 (35%) patients from inpa-tient clinic and intensive care unit, 2040 (2%) blood donors, 1023 (1%) dialysis patients, 4271 (4%) pregnant women, 2135 (2%) patients from infectious diseases department and 59 942 (56%) patients from other outpatient clinics. In sera of 90 (%0.08) patients aged 15-93 years, the HIV1-2 antibody was found as reactive by ELISA. 14 (15.9%) positive, 4 (4.5%) indeterminate and 70 (79.5%) negative results were found in samples investigated by LIA. Two samples which were not repeatedly reactive with ELISA were not tested by the confirmatory test. Confirmed HIV-positive cases over the years were distributed as 3 (21%) in 2014, 2 (14%) in 2015, 4 (29%) in 2016, and 5 (36%) in 2017, and the increase in cases according to years was found statistically significant (p<0.001). Conclusions: In our study, anti-HIV detection rates in patients were found to be consistent with other studies conducted on this subject.79.5% of patients with reactive ELISA and anti-HIV 1-2 tests were considered false-positive. These patients had autoimmune diseases, malignancy, pregnancy, and endocrinological disorders. As a result, HIV positivity among patients investigated by confirmatory tests has increased in recent years.