Xpert test for TB could help prevent deaths in southern Africa, but at substantial cost

(Press-News.org) A rapid test for tuberculosis (TB) could help to reduce TB deaths, improve TB treatment, and also offer reasonably good value for money if introduced in southern Africa, an area that has high rates of HIV and a type of TB that is resistant to some drugs (multi-drug resistant TB), according to a study published in this week's PLOS Medicine.

The World Health Organization (WHO) recently recommended the use of a new diagnostic test for TB (the Xpert MTB/RIF test), which can show a result within 2 hours, in people at high risk of multi-drug resistant TB and/or HIV-associated TB—two increasingly common conditions in many countries.

In a modelling study led by Nicolas Menzies from the Harvard School of Public Health in Boston USA, the authors investigated the potential health and economic consequences of implementing the Xpert test in Botswana, Lesotho, Namibia, South Africa, and Swaziland.

When compared to the current most commonly used testing approach (based on a sputum sample), the authors found that using Xpert instead would prevent an estimated 132,000 TB cases and 182,000 TB deaths in southern Africa over 10 years, reducing by 28% the proportion of the population with active TB.

The authors calculated that health service costs would consequently increase by US$460 million, with much of this extra cost due to increased costs for anti-HIV drugs (antiretroviral therapy) for people with TB-HIV co-infection who would now survive TB infection as a result of improved testing and treatment.

The authors also calculated that using Xpert in southern Africa would cost US$959 for every year of healthy life gained, ranging from US$792 in Swaziland to US$1257 in Botswana—levels which according to WHO standards, are considered cost effective. While these results suggest that scaling up Xpert can be a good health investment, the cost per healthy year gained is substantially higher in this study than in previous reports, and the economic results raise questions about affordability that will be critical for policy makers to consider.

The authors say: "Introduction of Xpert could substantially change TB morbidity and mortality through improved case-finding and treatment."

They continue: "Adoption of Xpert evidently offers reasonable value for its cost, based on conventional benchmarks for cost-effectiveness. However, the additional financial burden would be substantial, including significant increases in costs for treating HIV and multi-drug resistant-TB. "

The authors add: "Given the fundamental influence of HIV on TB dynamics and intervention costs, care should be taken when interpreting the results of this analysis outside of settings with high HIV prevalence."

### Funding: NAM and JAS were supported in part by funding from UNITAID. NAM was also supported by a training grant from the Massachusetts General Hospital's Program in Cancer Outcomes and Training (NIH Grant No. R25 CA092203). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: JAS and MM are members of the PLOS Medicine editorial board. The authors declare that no other competing interests exist.

Citation: Menzies NA, Cohen T, Lin H-H, Murray M, Salomon JA (2012) Population Health Impact and Cost-Effectiveness of Tuberculosis Diagnosis with Xpert MTB/RIF: A Dynamic Simulation and Economic Evaluation. PLoS Med 9(11): e1001347. doi:10.1371/journal.pmed.1001347

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CONTACT:

Nicolas A. Menzies
Center for Health Decision Sciences, Harvard School of Public Health, Boston Massachusetts, United States of America
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