[The diagnostic evaluation of rapid sputum technics for Pneumococcus in community-acquired pneumonia. The usefulness of Bayes theorem for clinical application].

This study aimed to quantify the diagnostic value of immunological techniques and methods for rapid analysis of sputum for pneumococcus, using sensitivity and specificity values reported in the literature to calculate positive and negative predictive values (PPV and NPV) according to Bayes formulas. Diagnostic gains of the test are calculated and compared to pretext probability. We located articles reporting sensitivity and specificity of counterimmunoelectrophoresis (CIE), coagglutination (CoA) and latex agglutination (LA) tests. We also calculated the probability ratios for the three tests. LA achieved the best overall diagnostic utility rating. CoA had the highest PPV, whereas LA offered the highest NPV. CIE was the least useful. These three tests are more useful at intermediate levels of prevalence of pneumococcus, which coincide with estimate in our population. We conclude that LA and CoA are of greater diagnostic utility for community acquired pneumonia, as they are useful for determining prevalence as well as for deciding initial antibiotic treatment.