Cost-effectiveness of routine diagnostic evaluation of pulmonary tuberculosis in a primary care unit in Brazil

SETTING: Primary health care unit in Rio de Janeiro City, Brazil. OBJECTIVE: To estimate and compare the cost-effectiveness of strategies used for passive case finding of pulmonary tuberculosis (PTB) cases using tests available at the primary care level. DESIGN: Data on PTB suspects were reviewed, and a decision model was developed using sputum smear microscopy and chest radiography (CXR) according to three different strategies for PTB detection. A cost-effectiveness analysis was performed to estimate the cost per correct PTB diagnosis. Mycobacterial culture was used to calculate the effectiveness of the strategies. Unit costs of health resource utilisation were obtained from the payer's perspective (the Brazilian Public Health System). RESULTS: For the evaluation of 254 PTB suspects, the total costs of strategies ranged from US$5369 to US$5944; the probability of a correct PTB diagnosis ranged from 0.66 to 0.86; the number of visits required to complete the diagnostic process ranged from two to three, and cost per PTB case identified ranged from US$47.93 to US$53.07. The cost-effectiveness of the three strategies studied varied between US$56.69 and US$72.55 per correct PTB case detected. CONCLUSION: A strategy in which sputum smears and CXR were requested for all PTB suspects at the initial evaluation was cost-effective, had a high probability of correct PTB diagnosis and could be accomplished in two visits.