Background: US Food and Drug Administration-approved enzyme-linked immunoassays (EIA) for determining type-specific herpes simplex virus (HSV) serostatus are widely used in clinical practice. We compared the performance of such assays with the University of Washington Western blot (UW WB) in patients who sought confirmation of their HSV serology result.
Methods: We reviewed charts of all persons evaluated at the Westover Heights Clinic in Portland, Oregon, from July 2010 through September 2015, who had a HSV EIA, followed by UW WB.
Results: Of 864 persons, 47% were women. The median age was 36 years (range, 18-73 years). Using UW WB to define infection status, 286 (33%) persons were HSV-1 seropositive only, 104 (12%) were HSV-2 seropositive only, 134 (16%) were both HSV-1 and HSV-2 seropositive, 235 (27%) were HSV seronegative, and 105 (12%) had indeterminate results. Compared with the UW WB as the criterion standard, EIA was 70.2% sensitive and 91.6% specific for HSV-1, and 91.9% sensitive and 57.4% specific for HSV-2.
Among 278 persons who were HSV-1 seropositive by EIA, 255 were confirmed by the UW WB (positive predictive value [PPV], 91.7%). Of the 360 persons that were HSV-1 seronegative by the EIA, 252 were seronegative by UW WB (negative predictive value [NPV], 70.0%). Among 381 persons with HSV-2 EIA seropositivity, 193 tested HSV-2 seropositive by the UW WB (PPV, 50.7%). Of the 270 persons HSV-2 seronegative by EIA, 17 were seropositive with the UW WB (NPV, 93.7%). Among 261 persons with an EIA HSV-2 index value = 1.1-2.9, 39.8% of results were confirmed by UW WB, compared with 78.6% of the 70 persons with an EIA index value of 3 or greater (P < 0.001). The risk of false-positive HSV-2 EIA results was higher in those with HSV-1 antibody (47.1% vs 37.1%, P = 0.036).
Conclusions: US Food and Drug Administration-approved EIAs have poor PPV for HSV-2 and poor NPV for HSV-1 in clinical practice. More accurate rapid type-specific HSV antibody tests are needed.
(C) Copyright 2017 American Sexually Transmitted Diseases Association