Establishing the etiology of pleural effusion is a diagnostic dilemma. This study aims to determine accuracy of serology (ELISA) using combined antigens in the diagnosis of TBPE compared with culture, histopathology and response to treatment.METHOD: Design: Validation study.SETTING: University of Santo Tomas Hospital, a tertiary institution.SUBJECTS: Sera of 160 patients with effusion by x-ray and or ultrasound and subjects of a broader validation of ELISA seen between January, 1995 to December, 2001 were analyzed.INTERVENTION: All had clinical evaluation, PPD test, thoracentecis/pleural biopsy, AFB smear, pleural tissue Bactec culture and histopathology; sera were kept at −20oC and batches analyzed using 16kDa and 38 kDa antigens (Pathozyme TB Complex Plus®, Omega Diagnostics Ltd, UK). Laboratory and pathologist had no prior knowledge of actual diagnosis. Patients were assessed independently and followed-up by same attending pulmonologist.OUTCOME MEASURES: Demographic profiles, laboratory results, disease categorization based on laboratory results and response to TB treatment; serology sensitivity, specificity, predictive values, likelihood ratios were derived.
At 50% TB prevalence, ELISA has 43.8% sensitivity, 93.8% specificity, a 87.5% positive predictive value, 62.5% negative predictive value, 7 likelihood ratio (+), 0.60 likelihood ratio (−), with 68.8% overall accuracy.
Given 50% TB prevalence, the test showed high specificity and positive predictive value with fairly good likelihood ratios.CLINICAL IMPLICATION: Using a combination of antigen proteins, ELISA can be a useful tool in the diagnosis of TBPE.
B.D. Briones, None.