Elsevier

Public Health

Volume 120, Issue 10, October 2006, Pages 976-983
Public Health

ORIGINAL RESEARCH
Development and evaluation of tuberculosis screening scores in Brazilian prisons

https://doi.org/10.1016/j.puhe.2006.06.004Get rights and content

Summary

Background

Tuberculosis (TB) is highly endemic in Rio de Janeiro State prisons. In addition to TB screening at entry and passive case detection, active case identification may be warranted.

Objectives

To develop and evaluate performances of scores aimed at identifying ‘tuberculosis suspects’ in order to target TB screening among inmates.

Methods

Systematic chest X-ray screening was carried out in two prisons (n=1910). TB was diagnosed among individuals with X-ray abnormalities by sputum microscopic examination and culture or, if bacteriological results were negative, by response to TB treatment. Using this strategy as a reference, the clinical score proposed in WHO guidelines ‘TB Control in Prisons’ was evaluated. Using the same variables in a logistic regression comparing TB and non-TB cases, another score was developed and evaluated. Finally, a ‘new score’, based on socio-demographic and clinical variables was developed and evaluated.

Results

When applied to our study population (prevalence of active TB: 4.6%), these scores missed many TB cases (sensitivities: 56%, 72%, 74%, respectively). Among the ‘TB suspects’, the probability of finding TB cases was low (positive predictive value: 10%). The scores had high negative predictive values (>97%); specificities (75%, 60%, 67%) were low. Performances were similarly poor for smear-negative and smear-positive cases.

Conclusion

The scores investigated performed poorly and would be unhelpful to target TB screening. Therefore, systematic X-ray screening may be considered, at least during the initial stages of the reinforced TB programme, in order to reduce the impressive burden of TB.

Introduction

In countries with high and intermediate tuberculosis (TB) endemicity, such as Brazil, TB is a major problem among prison populations.1, 2, 3, 4, 5 Indeed, most inmates originate from poor communities where TB is highly endemic, and prison conditions favour transmission.6, 7, 8 The situation is particularly alarming in Rio de Janeiro State prisons. In 2003, the incidence rate of TB was 15 times higher than in the general State population.

In keeping with World Health Organization (WHO) recommendations for prisons in low-income countries,9 TB control in Rio de Janeiro State prisons is based on the DOTS strategy. Passive TB case finding is currently being reinforced, and screening at entry has been initiated, but active case detection may also be warranted in this highly endemic setting. For active detection, WHO and the Red Cross9 recommend the use of an empiric score (referred to below as the ‘WHO score’), based on clinical and anamnestic variables. The aim is to identify a subgroup of ‘TB suspects’ who qualify for diagnostic investigations. This score is based on a combination of TB symptoms, body mass index (BMI) and a past history of TB. This score was disappointing as, in a recent screening programme in a Rio de Janeiro State Prison, many TB cases were missed.10

In the present intervention study, we used the results of a systematic X-ray screening carried out in two Rio de Janeiro State prisons as a reference by which to further evaluate the WHO score and a derived score based on multivariate analysis of the WHO score variables. Finally, we developed a new score based on all socio-demographic and clinical variables collected from each inmate. We then compared the performances of the three scores.

Section snippets

Study population, data collection and diagnosis of tuberculosis

The data used here were collected during two identical surveys conducted, cell after cell, in two Rio de Janeiro State prisons among male inmates aged over 18 years: an intermediate security prison (n=1171) was surveyed in March and April 2002, and a high-security prison (n=739) was surveyed from October to December 2003.

The procedures and diagnostic criteria for TB have been described in detail elsewhere.10 In brief, after giving written informed consent, each inmate was interviewed using a

Results

Of the 1910 inmates present in the two prisons when the survey was carried out, 1633 (85.5%) were included in the study.

In the first prison, 1081 out of 1171 (92.3%) inmates were available for screening. Three inmates refused to participate, 19 were excluded because of poor-quality films or incomplete records, and seven because they were under TB treatment when the study was initiated. Finally, 1052 inmates were included in the study.

In the second prison, a rebellion occurred during the study

Discussion

The WHO score performed poorly in our highly endemic study population (active TB prevalence rate: 4.6%). The derived score based on WHO score variables that were independently associated with TB in logistic regression analysis performed slightly better. The third score developed and tested here, based on the latter variables and on survey items, performed even better, but still failed to identify as TB suspect one-quarter of the inmates with documented TB.

Because of the occurrence of a

Acknowledgements

We warmly thank A.B. Espinola, W. Costa, J. Pires, D. Capone, G. Gerhardt and A. Barreto for their contribution to data collection, X-ray film interpretation and bacteriological diagnosis; A. Gégout-Petit for her contribution to statistical analysis; and M. Desvarieux for reviewing the manuscript.

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These authors contributed equally to this article.

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