Effectiveness and cost of rapid and conventional laboratory methods for Mycobacterium tuberculosis screening

Because delay in the diagnosis of tuberculosis (TB) contributes to the spread of disease and the associated mortality risk, the authors examined the effectiveness and cost of recent advances in methods of diagnosing TB and testing for drug susceptibility, comparing these rapid methods to traditional approaches.

Decision analysis was used to compare newer rapid and older nonrapid methods for diagnosing TB and testing for drug susceptibility. The average time to diagnosis, average time to treatment, average mortality, and cost of caring for patients evaluated for TB were compared.

Using a combination of solid medium and broth cultures, nucleic acid probes for identification, and radiometric broth drug susceptibility testing would lead to diagnosis on average 15 days faster and to appropriate therapy on average five days sooner than methods currently employed by many U.S. laboratories. The average mortality would drop by five patients per 1000 patients evaluated (31%) and the average cost per patient would drop by $272 (18%).

In this era of cost containment, it is important to incorporate test sensitivity and specificity when evaluating technologies. Tests with higher unit costs may lead to lower medical expenditures when diagnostic accuracy and speed are improved. U.S. laboratories should employ available rapid techniques for the diagnosis of TB.