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March 3, 1969

Specificity of the FTA-ABS Test for Syphilis: An Evaluation

Author Affiliations

From the Venereal Disease Program (Drs. Mackey and Scotti) and the Research and Therapy Evaluation Statistics Service, Venereal Disease Program (Mrs. Price), the National Communicable Disease Center, Health Services and Mental Health Administration, Public Health Service, Atlanta; and the Depart-ment of Dermatology, Baylor University College of Medicine, Houston (Dr. Knox). Dr. Mackey is now a fellow in dermatology at the University of Virginia Medical Center, Charlottesville; Dr. Scotti is a fellow in medicine at the Mayo Clinic, Rochester, Minn.

JAMA. 1969;207(9):1683-1685. doi:10.1001/jama.1969.03150220099011

In this evaluation of the fluorescent treponemal antibody-absorption (FTA-ABS) test, special emphasis is placed on its specificity as opposed to sensitivity. Among a total of 827 persons tested, there were five with a reactive FTAABS test confirmed by the Control Laboratory, and a non-reactive Treponema pallidum immobilization test accompanied by no clinical or historical evidence of syphilis. These five persons represent 0.6% of the total tested and 1.4% of those with a reactive FTA-ABS test. Three of these patients had diseases in which abnormal globulins frequently are found—rheumatoid arthritis, autoimmune hemolytic anemia due to lymphosarcoma, and alcoholic cirrhosis; two had no recorded evidence of disease. All were more than 50 years of age. Whether these cases represent old syphilis or false positive reactions to the FTA-ABS test is problematical.