Itsuhiro Nakagiri and Hideho Wada
Objective: In this research we followed up 31,041 HIV screening test results using immunochromatography assays to investigate the incidence of false-positive test results and the time duration within which false positives continued to be produced. Methods: Of the 31,041 cases reviewed, 13 cases returned a false positive result upon initial screening, and were retested, using the same assay, at least twice over 3 years. Results: The patients ranged in age from 12 to 89 years, with a median age of 68 years, and the male:female ratio was 4:9. The time from the first medical examination to the second assessment ranged from 89 to 519 days, with an average of 239.7 days. Of the 13 cases, four produced false-positive results for the p24 antigen, and nine were false-positive for the HIV antibody. Five individuals continued to produce false-positive results on further investigation, while eight presented negative results. The five cases with persistent false-positive results included a tendon sheath incision enforcement case, in which the falsepositive antibody reaction persisted for 883 days, and an intraocular lens insertion case in which the false-positive reaction persisted for 800 days. The individual metabolic characteristics of the patients may contribute to the false-positive HIV result persisting long term. The HIV test results of eight cases were negative after the initial false-positive results. We hypothesize that a nonspecific product was produced through the interaction between a therapeutic drug and the patient’s metabolism to produce transient false-positive reactions. These eight cases were reassessed at an average of 298 days after the first false-positive results, and the nonspecific product produced temporarily might have disappeared within this time. Conclusion: If preoperative HIV screening test is carried out before the therapeutic drugs have taken effect, the number of false-positive reactions may be reduced.
