Prognostic variables for high titres in a fluorescent antibody test to diagnose tuberculosis.
METHODS
The four hospitals and a tuberculosis clinic in the province of Zeeland, The Netherlands.


OBJECTIVE
To assess the usefulness of PPD antibody measurement in the diagnosis of tuberculosis in patients admitted to hospital.


METHODS
Sixty-one patients presenting with active tuberculosis, and 215 control patients were included in the study. Initial serum PPD antibody titres were determined with a macrophage uptake Fluorescent antibody test (MuFat) to construct a discrimination model between Tuberculosis (TB) and non-TB. We also retrospectively collected clinical parameters of the TB patients at presentation. Univariate and multivariate logistic regression are used to identify variables predicting high antibody titres.


RESULTS
In TB patients, the presence of clinical symptoms (OR=10.63) and the presence of at least two concurrent non-lymph node disease localizations outside thorax and abdomen (OR=13.94) are necessary and sufficient to predict high titres. The logistic model shows a significant contribution of the 2log (titre) to the discrimination between TB and non-TB patients. At a cut-off value of 128, a specificity, sensitivity, and positive predictive and negative predictive values of 97%, 39%, 80% and 85%, respectively, are calculated in the study cohort.


CONCLUSIONS
Our data suggest an application of the test at high cut-off values for timely diagnosis of difficult-to-diagnose TB patients. The results of this retrospective study will have to be confirmed in further prospective studies.
Doveren
Rob F C
RF
Emergency Department, St. Vincentius Hospital, St. Vincentiusstraat 20, B-2018 Antwerp, Belgium. r.doveren@zeelandnet.nl
Goudswaard
Jan
J
Hendriks
Jan C M
JC
Bins
Marijn C
MC
Belzen
Cees van
Cv
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004812:Epidemiologic Methods; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods; D006801:Humans; D008264:Macrophages / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D014373:Tuberculin; D014376:Tuberculosis / Q000175:diagnosis*
D014373:Tuberculin