Transthoracic needle aspiration biopsy for the diagnosis of localised pulmonary lesions: a meta-analysis

Background-Persisting controversy surrounds the use of transthoracic needle aspiration biopsy (TNAB) stemming from its uncertain diagnostic accuracy. A systematic review and meta-analysis was therefore conducted to evaluate the accuracy of TNAB for the diagnosis of solitary or multiple localised pulmonary lesions. Methods-Searches for English literature papers in Index Medicus (1963-1965) and Medline (1966-1996) were performed and the bibliographies of the retrieved articles were systematically reviewed. Articles evaluating the accuracy of TNAB in series of consecutive patients presenting with solitary or multiple pulmonary lesions were considered. Only papers in which greater than or equal to 90% of patients were given a final diagnosis according to an appropriate reference standard were included in the meta-analysis. Results-A total of 48 studies were included and five meta-analyses were conducted according to four diagnostic thresholds. From the pooled sensitivity and specificity corresponding to each diagnostic threshold, associated likelihood ratios (LRs) were derived for malignant disease as follows: (1) malignant versus all other categories, LR = 72; (2) malignant or suspicious versus all others, LR = 49; (3) suspicious versus all categories but malignant, LR = 15; (4) benign versus all others, LR = 0.07; and (5) specific benign diagnosis versus all others, LR = 0.005. Differences in methodological quality of the studies, needle types, or whether a cytopathologist participated in the procedure failed to explain the heterogeneity of the results found in almost every metaanalysis. Given a 50% probability of malignancy prior to the TNAB, post-test probabilities of malignancy upon receiving the results would be malignant, 99%; suspicious, 94%; non-specific benign, 7%; and benign with a specific diagnosis, 0.6%. Conclusions-Given the intermediate pre-test probabilities that would probably lead to performing TNAB, findings of "malignant" or of a specific diagnosis of a benign condition provide definitive results. Findings of "suspicious" markedly increase the probability of malignancy, and "benign" markedly decreases it but may not be considered definitive.