Situating the prevention of tuberculosis within curative services is unlikely to lead to a reduction in the overall burden of the disease. Additional public health approaches are called for.
The “Stop TB Strategy” is the World Health Organisation's latest plan to build on the success of the DOTS (Directly Observed Treatment, Short-course) campaign. It aims to dramatically reduce the global burden of the disease by 2015, in line with the Millennium Development Goals. It plans to achieve this goal by providing universal access to high-quality diagnostic procedures and patient-centred treatment. It intends to pursue DOTS expansion and enhancement, address the concerns related to multi-drug resistance and those infected with human immunodeficiency virus (HIV), strengthen health systems, engage care providers, empower people and communities, and promote research. While much progress has been made, critical reflection raises many unaddressed concerns and crucial challenges, which make sceptics argue that the strategy will not achieve its ambitious goals.
Impact of tuberculosis: Billions of people are infected with tubercle bacilli and many millions develop the disease every year. Over a hundred million live with the disease, while over two million die of the infection annually. The vast majority of the infected are poor and most of those who die live in poverty in low and middle-income countries. The risk of developing the disease increases exponentially among people infected with HIV.
The DOTS programme treats the infection and reduces the prevalence of the condition. The proven benefits of the programme include high cure rates, reduced death rates, decline in the number of treatment-resistant patients and decrease in new infections. The programme has many other advantages, including prevention of bacterial resistance to key medication. This is achieved by providing reliable diagnosis, directly observed treatment, fixed combination doses, blister packs, balanced regimens, trained health workers and restricting its use to treat appropriate disease. It also increases compliance to medication, the lack of which is a weakness of most ambulatory programmes, by supervision and monitoring. It is said to increase cure rates to over 90 per cent compared to 60 per cent in unsupervised regimens.
Problems with DOTS: Many problems plague the DOTS programme world-wide. These include lack of political commitment, poor funding, limited human resource, restricted supply of anti-TB medication, meagre information systems and inadequate organisation of services. These are, however, obstacles that can be overcome with greater political will, increased finances and better organisation. However, there are other serious challenges related to the DOTS approach that argue that the programme will not achieve its aims.
Historical solutions: There is evidence that the rate of tuberculosis in the West dropped long before the introduction of anti-tuberculosis medication. The provision of adequate housing, reduction of overcrowding, improved nutrition and sanitation and better work environments were the reasons for winning the war against TB in the western world. Unfortunately, the current medicalisation of public health, where all problems are viewed through the “medical lens,” has resulted in Indian and international agencies focussing exclusively on medical solutions such as DOTS. The high cost of socio-environmental interventions makes the improvement of housing and work environments less attractive from a financial point of view. It is also argued that the direct impact of such interventions on the reduction of transmission is less than that achieved by DOTS. Nevertheless, sole reliance on the current curative approaches to the problem, which requires long-term public health solutions, will prove ineffective with the unchecked spread of the infection.
Prevention based on cure: The DOTS strategy is essentially a curative medical approach to treat tuberculosis. However, prevention based on curative medical treatments has never eradicated any disease. Only vaccine-based approaches have achieved such success, as in the case of small pox. However, vaccination with BCG provides variable protection from serious disease and is not considered a mainline strategy for the prevention of TB. The use of curative approaches based on routine health services to prevent diseases has never had a significant impact on prevention. This approach fails as it essentially employs downstream interventions and is not capable of preventing the spread of primary infections. The detection of cases in hospitals implies that these patients would have contributed to the spread of the infection prior to detection and even during the early phase of treatment. The absence of routine screening of the contacts of diagnosed cases is a missed opportunity. In addition, situating prevention within routine health services implies problems related to establishing and maintaining the quality of services and managing competing priorities. These strategies fail to address the core context of tuberculosis which is related to poverty with its associated under-nutrition and overcrowding.
Malnutrition worries: The fixed-dose combinations recommended by DOTS, while good for the average person, can cause major problems for the under-nourished. With over a third of the poor (read lower castes and tribes) malnourished, this circumstance has a significant impact on the majority of people ravaged by the disease. While some consideration is given to the very grossly malnourished, the “higher” doses the person receives in relation to the body weight produces not only incapacitating side-effects which lead to the discontinuation of treatment but also serious toxicity due to medication. Sacrificing the principle of titrating medication to body weights (which is the standard medical practice) at the altar of programmatic concerns needs reconsideration. There is also evidence to suggest that in the malnourished, nutritional supplementation prior to the onset of curative treatment results is better tolerance of side-effects. The current national nutritional policy with its subsidised food programme for the poor only provides calories through carbohydrates instead of a balanced diet, resulting in lowered immunity and increased susceptibility to infection.
Ground realities: The Revised National Tuberculosis Control Programme (RNTCP) assumes a good cure rate with treatment. It considers people whose sputum is negative for tuberculosis bacilli after 6 months of treatment as being cured of the disease. However, the RNTCP does not follow up patients. There is a need to move beyond such end points (of being sputum smear negative) and monitor patients for recurrence and relapse of symptoms and disease in order to assess the effectiveness of the programme. Anecdotal evidence also argues that the direct observation of medication compliance even for the first two months of the intensive treatment phase is less than perfect and that non-compliance in a minority of patients is an issue. This is particularly important in the context of the increase of multi-drug resistant (MDR) disease. Notified MDR TB also is said to be a fraction of the estimated prevalence in India and enrolment for MDR treatment is patchy across the country.
The way forward: The persistently high rate of new case detection in many low and middle-income countries argues that the current strategy of employing curative treatment and situating it within the routine health care system will not result in the eradication of the disease. The ideal public health solution of a vaccine to prevent the disease is not yet on the horizon. Education of the general population through the mass media is necessary. Augmenting nutrition, albeit through a balanced diet, in those who are underweight will boost natural immunity. The provision of good housing and work environments will reduce the spread of infection. The high prevalence of TB in India argues for active case finding. School and workplace surveys should be mandatory as should the screening of contacts of newly diagnosed cases. Newer diagnostic tests need to replace the less efficient sputum smear microscopy. While the fixed dose combination has many advantages in large programmes, there is still a need to titrate the dose for individuals. Audit of supervision of the direct observation of medication compliance is vital in limiting non-compliance and preventing multidrug resistance. A follow-up of all treated cases to identify relapses and to evaluate the effectiveness of the programme is crucial. The current programme is a curative strategy for populations, without a specific focus on the individual as demanded by good clinical practice. Nor does it champion good public health approaches.
The economics of the national programmes in low and middle-income countries sometimes shifts ownership from national governments to international agencies, thus disempowering local and regional stakeholders. The location of prevention within curative services also implies that the stakeholders need to address other competing interests for sustained intervention. Increasing the collaboration between HIV and TB services and national programmes is an urgent need. Maintaining quality services for people with tuberculosis is cardinal in preventing drug resistance and is inextricably linked to the future of the TB epidemic. There is need to ensure sufficient human resource and technical capacity.
Many of these arguments are well known within the medical fraternity. The challenge lies in moving beyond curative approaches to public health strategies which, although more expensive in the short-term, will result in disease control and possible eradication.
(Professor K.S. Jacob is on the faculty of the Christian Medical College, Vellore.)