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. 2018 Jul 19;13(7):e0200523.
doi: 10.1371/journal.pone.0200523. eCollection 2018.

Delayed diagnosis and treatment of tuberculosis in HIV+ patients in Mozambique: A cost-effectiveness analysis of screening protocols based on four symptom screening, smear microscopy, urine LAM test and Xpert MTB/RIF

S Orlando  1 , I Triulzi  2 , F Ciccacci  1 , I Palla  2 , L Palombi  1 , M C Marazzi  3 , M Giuliano  4 , M Floridia  4 , S Mancinelli  1 , E Mutemba  5 , G Turchetti  2
Affiliations

Delayed diagnosis and treatment of tuberculosis in HIV+ patients in Mozambique: A cost-effectiveness analysis of screening protocols based on four symptom screening, smear microscopy, urine LAM test and Xpert MTB/RIF

S Orlando et al. PLoS One. .

Abstract

Background: Tuberculosis (TB) represents the ninth leading cause of death worldwide. In 2016 are estimated 1.3 million TB deaths among HIV negative people and an additional 374,000 deaths among HIV positive people. In 2016 are estimated 1.4 million new cases of TB in people living with HIV (PLHIV), 74% of whom were living in Africa. In light of these data, the reduction of mortality caused by TB in PLHIV is strongly required specially in low-income countries as Mozambique. According to international guidelines, the initial TB screening in HIV+ patients should be done with the four symptoms screening (4SS: fever, current cough, night sweats and weight loss). The diagnostic test more used in resource-limited countries is smear microscopy (SMEAR). World Health Organization (WHO) recommended Lateral Flow urine LipoArabinoMannan assay (LF-LAM) in immunocompromised patients; in 2010 WHO endorsed the use of Xpert Mycobacterium Tuberculosis/Rifampicin (MTB/RIF) test for rapid TB diagnosis but the assay is not used as screening test in all HIV+ patients irrespectively of symptoms due to cost and logistical barriers. The paper aims to evaluate the cost-effectiveness of three screening protocols: standard (4SS and SMEAR in positive patients to 4SS); MTB/RIF; LF-LAM / MTB/RIF.

Methods: We developed a model to assess the cost-effectiveness of the MTB/RIF protocol versus the common standard and LF-LAM / MTB/RIF protocol. The model considered a sample of 1,000 HIV+ antiretroviral treatment naïve patients in Mozambique. We evaluated disability-adjusted life year (DALY) averted for each protocol, cost per DALY, and incremental cost-effectiveness ratio (ICER), over 1-year, assuming a national healthcare system perspective. The model considered the delayed diagnosis as the time elapsed between a false negative test and the diagnosis and treatment of TB. Additional health system organization delay is defined as the time interval between positive test and treatment initiation caused by a delay in the delivery of results due organization of services. We conducted a sensitivity analysis on more relevant variables.

Results: The MTB/RIF protocol was cost-effective as compared to the standard protocol with an ICER of $56.54 per DALY saved. In a cohort of 1,000 patients MTB/RIF and LF-LAM / MTB/RIF protocol generated 1,281 and 1,254 DALY's saved respectively, with a difference of 174 and 147 DALY respect to the standard protocol. The total cost of MTB/RIF protocol was lower ($92,263) than the standard ($147,226) and the LF-LAM / MTB/RIF ($113,196). Therefore, the cost per DALY saved including new infections due to delayed diagnosis with the standard protocol was $79.06, about 5 fold higher than MTB/RIF and LF-LAM / MTB/RIF protocols. The cost of additional TB infections due to delays in diagnosis plus health system delay seemed the more relevant costs. The low sensibility and sensitivity of the standard protocol led to a high number of false negatives, thus delayed TB diagnoses and treatment lead to the development of newly transmitted TB infections.

Conclusions: Our study shows that the MTB/RIF adoption could lead to an increasing of TB case-finding and a reduction in costs compared with standard and LF-LAM / MTB/RIF protocols.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. TB screening protocols in HIV+ patients.
Fig 2
Fig 2. Itemized costs as percentage of total costs.
Fig 3
Fig 3. Tornado diagram.
One-way sensitivity analysis of ICER in MTB/RIF protocol versus Standard protocol (including newly TB transmitted infections due to delayed diagnosis). Only parameters with greatest influence are shown. Vertical line is at base-case ICER of $56.54.
Fig 4
Fig 4. Tornado diagram.
One-way sensitivity analysis of cost per DALY saved (including newly TB transmitted infections due to delayed diagnosis) in MTB/RIF protocol. Only parameters with the greatest influence are shown. Vertical line is at base-case cost per DALY saved of $14.18.
See this image and copyright information in PMC

References

    1. World Health Organization. Global tuberculosis report 2017. Geneve, Switzerland: WHO, 2017. WHO/HTM/TB/2017.23.
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    1. World Health Organization. Tubercolosis and HIV. Available at: http://www.who.int/hiv/topics/tb/en. Accessed 17 November 2017.
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    1. UNAIDS, Fact sheet–Wold AIDS Day 2017, Latest statistics on the status of the AIDS epidemic. Available at: http://www.unaids.org/en/resources/fact-sheet.

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