Comparison testing of current (PPD-S1) and proposed (PPD-S2) reference tuberculin standards.
Since 1951, the tuberculin PPD-S1 has been used to standardize commercial PPD reagents and perform special tuberculin surveys. PPD-S1 is now in short supply and a new standard (PPD-S2) has been manufactured. To determine if PPD-S2 is equivalent and can replace PPD-S1, we conducted a double-blind clinical trial. Between May 14 and October 28, 1997, 69 subjects with a history of culture-proven tuberculosis (TB patients) and 1,189 subjects with a very low risk for TB infection were enrolled, received four skin tests (with PPD-S1, PPD-S2, and one each of the commercially available PPDs), and had reactions measured by two trained observers. Among the TB patients, we found statistically indistinguishable immunogenicity (mean reaction size +/- standard deviation): 15.6 +/- 6.6 mm for PPD-S1 and 14.8 +/- 5.6 mm for PPD-S2. Among low-risk subjects, the tests had equally high specificities (PPD-S1, 98.7% and PPD-S2, 98. 5%), using a 10-mm cutoff. The number of discordant (negative versus positive) interpretations for PPD-S2, assuming that low-risk subjects who had a >/= 10 mm reaction to PPD-S1 were truly infected, was low (0.5%) and indistinguishable from the rate of discordant interpretations of the same test when read by two different observers (0.8%). The study results indicate that PPD-S2 is qualified to be used as the new U.S. reference standard for PPD tuberculin.
Villarino
M E
ME
Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. MEV1@CDC.GOV
Brennan
M J
MJ
Nolan
C M
CM
Catanzaro
A
A
Lundergan
L L
LL
Bock
N N
NN
Jones
C L
CL
Wang
Y C
YC
Burman
W J
WJ
D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D012680:Sensitivity and Specificity; D014373:Tuberculin; D014374:Tuberculin Test / Q000592:standards*; D014376:Tuberculosis / Q000175:diagnosis
D014373:Tuberculin