Effectiveness of the Rapid HIV Test versus Fourth Generation ELISA in the Approach of Occupational Exposure

Background:

Our objective was to evaluate the efficacy of a rapid HIV-test for source diagnosis compared with standard serology for reduction in post exposure prophylaxis (PEP) over prescription.

Methods:

A prospective cohort study comparing a rapid HIV-test and a fourth generation Enzyme-Linked Immunosorbent Assay (ELISA); upon report both tests were performed on the source patient (SP). We included HCW >18 years, who suffered an OE (by needle stick injury or by mucocutaneous exposure) that notified the infection control unit within ≤48hrs in which an identifiable SP with an unknown HIV-antibody status was involved. We excluded HCW with another OE (<6 months) and those who did not signed the informed consent.

Results:

A total of 50 OE met the study criteria. Median age of the HCW was 23 years (18-30); 52% were women. The majority of the OE occurred in the emergency department (46%, n=23). Needle stick injury was the most frequent mechanism of OE (90%, n=45). Nursing students were the most exposed HCW registering 26% (n=13) of the total of OE, followed by medical students with 22% (n=11).

The median of time between the OE and the report to the infection control unit was 1:00h (range 00:05-10:00); the median of time between the report and the administration of PEP was 00:30h (range 00:05-02:07). The time between the report and the result of the rapid HIV-test was significantly lower than the time for the ELISA results; 01:05h (range 00:25-04:04) vs 05:46h (range 02:36-67:15) (P=0.0001, CI95% 03:58-09:18). The median time between the phone call to the HCW to the face to face notification of the ELISA test was 2:47h (range 0:02-14:16h). All of the results for ELISA and the rapid HIV-test from the source patients were negative (Kappa=1.00 between both tests).

None of the HCW had a history of hepatitis B or C infection. At baseline none of the HCW and none of the SP were positive for HBV and 1 HCW and 2 SP were positive for HCV. No one seroconverted to HCV during follow up.

Conclusion:

In this study the use of a rapid HIV-test for source patients correlated perfectly with ELISA and hypothetically if the rapid test result was obtained in <2hr from the moment of the OE we could have withheld PEP in 19 cases (38%) and in 38 (76%) if the result was obtained in <4h; this would have corresponded to a reduction of 23/57 doses (40.3%) for the former and 38/57 (66.6%) for the latter time periods.