USE OF DISCRIMINANT-ANALYSIS TO ASSESS DISEASE-ACTIVITY IN PULMONARY TUBERCULOSIS WITH A PANEL OF SPECIFIC AND NONSPECIFIC SERUM MARKERS

Several cell activation markers, acute phase reactants, enzymes, and a ntituberculous antibody serum levels have been proposed as possible ma rkers to monitor disease activity in patients with tuberculosis. They have all shown limited sensitivity or specificity. The authors therefo re attempted to generate a canonical variable using discriminant analy sis, including sensitive and specific parameters, to be a reliable mar ker in classifying patients correctly during the course of pulmonary t uberculosis. The following parameters were selected: two soluble cell activation markers (soluble interleukin-2 receptor and sCD8); the Leve ls of immunoglobulin (Ig)G and IgM antibodies against the A60 antigen complex; and the presence of specific antibodies directed to eight dif ferent A60 components, revealed by Western blot analysis. The tests we re performed on sera from three groups of patients with pulmonary tube rculosis. The first group comprised 25 patients with onset tuberculosi s, clinically active (OTCA), evaluated at the time of admission. The s econd group included 28 patients with chemotherapy-treated tuberculosi s, clinically active (OTCA), 2 months after therapy had begun. The thi rd group included 20 patients with tuberculosis, nonclinically active (TNCA), who had had at least 1 year of effective therapy. The authors obtained an 80.9% rate of correct classification for the three groups and a rate of 100% when OTCA and TNCA were compared. The patients with CTCA were scarcely differentiated and tended to be distributed into t he two other groups. To improve the separation between patients with C TCA and those with OTCA, a second canonical variable was generated wit h a 91.7% rate of correct classification, as compared with 71% obtaine d using the sCD8 as the best single variable.The mean values of the la st canonical variable were statistically different (Mann-Whitney test, P=.049) when stratified for acid fast bacilli-positive or negative CT CA patients (microscopic detection). Three patients, followed during t he entire course their disease, were, as expected, correctly positione d with respect to the subsequent disease phases.