Labeling patients with false-positive FTA-ABS.

Abstract

To the Editor .—In the December 1976 issue (102:729-731), Dr Gary Becker labeled four patients with persistently positive (1+, 2+ ) FTA-ABS as having false-positive reactions. It is well known that approximately 25% of the patients with late syphilis will have a negative VDRL, while the FTA-ABS remains positive. We do not believe Dr Becker offered sufficient evidence to label these patients as having false-positive reactions. After eliminating various factors known to cause a false-positive FTA-ABS (eg, pregnancy, collagen disease, other treponematoses, abnormal globulins, smallpox vaccination, and drug-induced lupus), he relied on a negative Treponema pallidum immobilization test (TPI) to rule out the diagnosis of syphilis. He mentions the fact that the TPI is slightly less sensitive than the FTA-ABS (90% compared with 98% in a study by Atwood et al 1 ). This of course means that the TPI may be negative in syphilis while the FTA-ABS is positive. The TPI