Papers Achieving the millennium development goals for health

# Cost effectiveness analysis of strategies for tuberculosis control in developing countries

BMJ 2005; 331 (Published 08 December 2005) Cite this as: BMJ 2005;331:1364
1. Rob Baltussen, health economist (r.baltussen{at}erasmusmc.nl)1,
2. Katherine Floyd, health economist2,
3. Christopher Dye, coordinator3
1. 1Institute for Medical Technology Assessment (iMTA), Erasmus Medical Centre, PO Box 1738, 3000 DR Rotterdam, Netherlands
2. 2Stop TB Department, World Health Organization, Geneva, Switzerland
3. 3Stop TB Department, World Health Organization, Geneva, Switzerland
1. Correspondence to: R Baltussen
• Accepted 12 October 2005

## Abstract

Objective To assess the costs and health effects of tuberculosis control interventions in Africa and South East Asia in the context of the millennium development goals.

Design Cost effectiveness analysis based on an epidemiological model.

Setting Analyses undertaken for two regions classified by WHO according to their epidemiological grouping—Afr-E, countries in sub-Saharan Africa with very high adult and high child mortality, and Sear-D, countries in South East Asia with high adult and high child mortality.

Data sources Published studies, costing databases, expert opinion.

## Results

The tuberculosis model replicated the strong increase in the incidence of infectious disease in Afr-E from around 1990, with an annual growth rate of about 10% between 1990 and 2000. In Sear-D, the tuberculosis model estimates an annual decline in incidence of 1% in the same period.

### Intervention effects

Tables 2 and 3 show the health effects, costs, and cost effectiveness of the different interventions in Afr-E and Sear-D. When only smear-positive cases are treated in DOTS programmes and the geographical coverage level is 95%, an average of 0.62 million people are treated in Afr-E and 1.38 million in Sear-D each year. The annual cost averages $Int366m in Afr-E and$Int536m in Sear-D. The total number of DALYs averted per year averages 44.8 million in Afr-E and 76.6 million in Sear-D. Adding treatment of smear-negative and extra-pulmonary cases or of multidrug resistance cases increases costs considerably but increases the DALYs averted only slightly. Increasing the coverage level from 50% to 95% roughly doubles both costs and effects for each of the four interventions considered.

Table 2

Annual numbers of patients treated, total costs in international dollars ($Int), total effects, and average and incremental cost effectiveness for various tuberculosis control interventions in the Afr-E region View this table: Table 3 Annual numbers of patients treated, total costs in international dollars ($Int), total effects, and average and incremental cost effectiveness for various tuberculosis control interventions in the Sear-D region

View this table:

### Limitations of study

Our study has several limitations. Some of these are related to the general methodological approach to cost effectiveness analysis, and are discussed in more detail elsewhere in this series.18 Others are more specific to tuberculosis control.

In the absence of better data, we assumed that key model parameters such as tuberculosis transmission rates are the same across regions. Studies of the transmissibility of multidrug resistant tuberculosis have produced variable results, and our assumption that multidrug resistant tuberculosis and drug susceptible tuberculosis are equally transmissible contrasts with the more conservative range of assumptions considered in an earlier study.11

Evidence about the costs of increasing the percentage of tuberculosis cases that are treated in DOTS programmes remains limited, and, despite building in extra costs to allow for this, we may have underestimated them. The only published cost data for DOTS-Plus programmes are from Peru.

Our study results may not be directly generalisable to other settings because of differences in regional epidemiological and economic profiles. However, the results of studies for other regions that used similar methods show similar results.27

The strengths of our study include the use of a tuberculosis model that has been published and widely applied,20 consideration of combinations of interventions, inclusion of transmission in the analysis, use of a generic measure of effectiveness, and testing of important assumptions through sensitivity analyses.

### Implications of results

Our results have three major policy implications. Firstly, they reinforce the principle that treatment of smear-positive cases in DOTS programmes must be the basis of any tuberculosis control strategy, as has become standard practice in almost all control programmes.

Secondly, they show that there is a strong economic case for treating smear-negative and extra-pulmonary cases in DOTS programmes and for treating multidrug resistant cases in DOTS-Plus programmes, as set out in WHO's new “Stop TB” strategy and the second global plan for tuberculosis control (see box 2).

Finally, our study shows that substantial scaling up of all three interventions is needed in the next 10 years if the millennium development goal and related targets for tuberculosis control are to be reached. In particular, the case detection rate must be improved so that many more tuberculosis cases are diagnosed and successfully treated, in line with existing targets. Improving the case detection rate will mean ensuring that people who currently have access to treatment facilities are covered and that coverage is expanded to people who do not currently have access. Such scaling up would bring the millennium development goal and related Stop TB Partnership targets within reach in South East Asia and achieve major progress towards these targets in Africa.

What is already known on this topic

Studies have shown that DOTS treatment of new cases of smear-positive tuberculosis to be a cost effective intervention in Africa, but data for other regions of the world or for treating smear-negative and extra-pulmonary cases and multidrug resistant tuberculosis are scarce

Most studies have not considered the impact of interventions on transmission or interactions among interventions and have used measures of effectiveness that do not allow comparisons with other health interventions

This comprehensive and standardised analysis of different interventions in Africa and South East Asia accounts for both transmission and interactions among interventions

Treatment of smear-positive, smear-negative, and extra-pulmonary cases in DOTS programmes and treatment of multidrug resistant cases in DOTS-Plus programmes are cost effective in both regions

These results provide a strong case for substantial investment to improve case finding and to implement these interventions on a much wider scale

Further details of the methods used appear on bmj.com

## Footnotes

• Contributors All authors contributed to the conception and design of the study, interpretation of data, and drafting of the manuscript. RB performed the technical analysis. All authors approved the submitted version of the manuscript. RB is guarantor for the manuscript.

• Funding RB received funding from WHO and conducted the research in collaboration with WHO staff. For WHO staff, no external funding was received.

• Competing interests None declared.

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