[Quality of bacillus identification tests in the Federal District (Brazil)--a reliability testing]

In Brazil, one of the priorities in the fight against the tuberculosis is the evaluation of laboratories' performance through the quality control of baciloscopic tests. This study was meant to evaluate the reliability of the tests carried out by the Tuberculosis Control Program of the Federal District, Brazil. It is a descriptive study, made out of revised glass slides at the reference laboratory, from 1988 up to 1999. A double-blind comparison of the results of the smear readings obtained in the outskirts and central laboratories was made. The concordances/discrepancies were analyzed through Kappa and the Confidence Interval (CI). From a total of 62,487 glass slides, we evaluated 7,756 baciloscopic tests. The discrepancy results represented 1.9% of false-positive and 0.8% of false-negative. Until 1997, 66.5% of the positive baciloscopic tests had been revised, but when the quality control was implemented the results grew up to 90.1%. The Kappa obtained a very good reliability but didn't match with the CI results. The quality control will increase the reliability of the tuberculosis diagnose although the evaluation depends on the use of sensitive reproducing tests.