SUMMARY

Patients with HIV experience high mortality and severe morbidity if co-infected with

tuberculosis. This is especially true in countries of sub-Saharan Africa like Nigeria with high

burden of both diseases where diagnostic capacity for TB in HIV positive patients is poor. Early

diagnosis and treatment has been identified as an important strategy to mitigate these effects. A

cost and cost-effectiveness analyses of TB diagnostic strategies to reduce this adverse outcomes

was carried out.

A decision analysis model was developed to estimate the incremental cost, Life years gained, and

cost-effectiveness of 3 TB diagnostic algorithms. The base case scenario was an algorithm

relying on sputum smear, and chest radiography, which was compared to algorithms featuring

newer TB diagnostics (GeneXpert MTB/Rif and MODS). All relevant costs from a National TB

programme perspective using the timeframe of the first 6 months of ART was considered. We

conducted a one-way sensitivity analysis on parameters in the model.

When considering TB diagnosis and treatment costs, the cost per patient was $126.39 for current

practice, $76.96 for the algorithm with Xpert test, and $88.62 for the algorithm with MODS. Life

years gained was 0.9 for all 3 algorithms. The results showed that both new TB diagnostic

methods were more cost effective than base case scenario. The algorithm with Xpert test was

cheapest to achieve similar effectiveness compared with the MODS and base case. Sensitivity

analyses indicated that cost-effectiveness findings were robust.

This study showed that Xpert was cost-effective compared to MODS and base case algorithm.

Thus, these findings provide support for ongoing efforts to expand TB diagnostic capacity with

GeneXpert MTB/Rif.

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Key Words: HIV, tuberculosis, tuberculosis diagnosis, cost, cost- effectiveness, sub-Saharan

Africa, Nigeria

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CHAPTER ONE

INTRODUCTION

1.1       BACKGROUND INFORMATION

Tuberculosis (TB) is a highly infectious communicable disease caused by the bacterium

Mycobacterium tuberculosis (MTB). It most commonly affects the lungs (pulmonary TB) but

may also affect other parts of the body such as the spine, lymph nodes, brain, bone joints,

meninges and kidneys (extra-pulmonary TB).1

TB is a global health priority. Globally, 9.6 million new cases of TB occurred in 2014 with 1.5

million TB deaths.2 HIV infection is the most significant risk factor for the development of TB.

This is because HIV causes the reactivation of latent TB and predisposes infected individuals to

acquire new TB infections. TB on the other hand, is also known to accelerate HIV infection into

AIDS. This is one of the reasons why TB/HIV co-infection results in greater morbidity and

mortality.3,4 People living with HIV are 26 times (20 - 30) more likely to develop TB disease

than those who are HIV negative.5,6 Of the estimated 9.6 million incident TB patients in 2014,

12% (1.2 of 9.6 million) are infected with HIV. About half a million of these incident TB

patients have multi-drug resistant TB (MDR-TB), which is characterized by rapid deterioration

and high mortality in HIV positive patients. Sub-saharan Africa is disproportionately affected

with 74% of the 1.2 million HIV positive TB cases and 390,000 deaths in 2014.2,7 This

represented 25% of all deaths attributed to TB and one third of the deaths attributed to

HIV/AIDS. In Nigeria, the prevalence of TB was estimated at 330 per 100,000 population2 while

mortality was 44 per 100,000. Nineteen percent of TB cases were HIV positive.2