Asbestos bodies (AB) in respiratory secretions in bronchoalveolar lavage (BAL) identify subjects with lower airway AB content is a potential cause of pleural or pulmonary disease. The precision of this qualitative measure, however, has not been adequately analyzed.
Objective: To determine the sensitivity and specificity of finding AB in BAL fluid by conventional qualitative cytology in comparison with the quantification of AB in BAL fluid.
Method: BAL samples from 40 subjects exposed to asbestos (mean age 59.2 years; men/women 36/4) were processed in the following ways: 1) qualitative cytology and 2) quantification of AB in BAL fluid expressed as AB/ml. The concentration of AB in BAL fluid was considered the gold standard (upper limit of normal 1 AB/ml) for determining the precision of qualitative cytology.
Results: In 9 of the 40 cases (22.5%) AB was found in BAL liquid cytology, but in only five of them were AB counts greater than 1 AB/ml. AB counts also showed concentrations greater than 1 AB/ml for four patients whose qualitative results were negative. The sensitivity of a qualitative AB-positive finding for identifying subjects with potentially disease-causing AB concentrations was 0.55, while specificity was 0.87. We conclude that a qualitative finding of AB in BAL fluid is adequately specific, but that sensitivity is very low, an indication that AB concentration in BAL should be determined to adequately screen for patients at high risk of developing disease.