Smear plus Detect-TB for a sensitive diagnosis of pulmonary tuberculosis: a cost-effectiveness analysis in an incarcerated population

Abstract

BackgroundPrison conditions can favor the spread of tuberculosis (TB). This study aimed to evaluate in a Brazilian prison: the performance and accuracy of smear, culture and Detect-TB; performance of smear plus culture and smear plus Detect-TB, according to different TB prevalence rates; and the cost-effectiveness of these procedures for pulmonary tuberculosis (PTB) diagnosis.MethodsThis paper describes a cost-effectiveness study. A decision analytic model was developed to estimate the costs and cost-effectiveness of five routine diagnostic procedures for diagnosis of PTB using sputum specimens: a) Smear alone, b) Culture alone, c) Detect-TB alone, d) Smear plus culture and e) Smear plus Detect-TB. The cost-effectiveness ratio of costs were evaluated per correctly diagnosed TB case and all procedures costs were attributed based on the procedure costs adopted by the Brazilian Public Health System.ResultsA total of 294 spontaneous sputum specimens from patients suspected of having TB were analyzed. The sensibility and specificity were calculated to be 47% and 100% for smear; 93% and 100%, for culture; 74% and 95%, for Detect-TB; 96% and 100%, for smear plus culture; and 86% and 95%, for smear plus Detect-TB. The negative and positive predictive values for smear plus Detect-TB, according to different TB prevalence rates, ranged from 83 to 99% and 48 to 96%, respectively. In a cost-effectiveness analysis, smear was both less costly and less effective than the other strategies. Culture and smear plus culture were more effective but more costly than the other strategies. Smear plus Detect-TB was the most cost-effective method.ConclusionsThe Detect-TB evinced to be sensitive and effective for the PTB diagnosis when applied with smear microscopy. Diagnostic methods should be improved to increase TB case detection. To support rational decisions about the implementation of such techniques, cost-effectiveness studies are essential, including in prisons, which are known for health care assessment problems.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0678-x) contains supplementary material, which is available to authorized users.

Disparities in model-based cost-effectiveness analyses of tuberculosis diagnosis: A systematic review

“…Most studies (78%) were performed in high burden TB settings, i.e. Brazil, [ 34 , 35 , 38 , 47 , 48 ] India, [ 36 , 40 , 42 , 50 , 52 , 53 ] several countries in Southern Africa (Botswana, Lesotho, Namibia, South Africa and Swaziland), [ 31 , 35 , 43 , 51 – 53 ] and East Africa (Kenya, Malawi, Uganda, Tanzania and Zambia). [ 30 , 35 , 41 , 44 , 46 , 49 , 51 – 53 , 55 ] One study performed analysis in a high burden region, i.e.…”

“…[ 54 ] More than half of the studies (63%) were performed within 2011–2015. [ 29 , 32 , 36 , 38 – 43 , 48 – 55 ] The earliest study dated from 1998. [ 46 ]…”

Performance of a molecular assay to detect Mycobacterium tuberculosis complex DNA in clinical specimens: multicenter study in Brazil

“…Generally, the results of Detect-TB assay showed better specificity with composite diagnostic criteria when compared to laboratory criteria. In a previous study by our group, we demonstrated that smear microscopy plus Detect-TB assay was the most cost-effective initial diagnostic test for active TB when applied in a prison population with a high prevalence of active PTB, indicating that Detect-TB assay has great potential to be implemented under routine diagnostic conditions ( Schmid et al 2014 ). The overall rate of false negatives was higher when the Detect-TB assay was to composite diagnostic criteria (6.3%) than with bacteriological criteria (3.3%).…”

Polymerase chain reaction test in induced sputum of patients with pulmonary tuberculosis

“…In addition, 1 concern about this study is that almost 30% of active TB cases in this study were clinically diagnosed, and clinical assessment is not always reliable to be used as the gold standard in a comparison study. Another study that evaluated the same PCR test (Detect‐TB), and demonstrated high sensitivity and specificity, also used clinical outcome as the gold standard.…”