Nearly 2 million people die from tuberculosis each year, mainly in the poorest countries. The pathogen, Koch's bacillus, can pass easily by aerial infection from one individual to another. The spread of the disease, favoured by the Aids epidemic and the appearance of multi-resistant strains, has led the World Health Organization (WHO) to make tuberculosis control one of the world's main health priorities.
The existing treatment, which combines several antibiotics prescribed for a period of 6 to 8 months -- as against 18 months to 2 years still only a few years ago -- has proved efficient in 95 % of cases. However, this efficacy is called into question by the low adherence of patients to treatment, particularly in the most deprived areas, which are often indeed the worst hit by the disease. In spite of the WHO recommendation to administrate the treatment under the direct supervision of health care personnel who play the role of supporter (DOT : Directly observed therapy), more than 10% of patients stop the treatment before the prescribed period. This defaulting, along with irregularity in taking the medicines, creates increased risk of serious relapse, which opens the way to a rise in transmission events and the emergence of bacteria resistant to the prescribed antibiotics.
Starting from the principle that tuberculosis control must involve the identification of the obstacles to full comprehensive access to treatment, IRD researchers and their partners (1) studied, in Senegal, the different geographical, behavioural and socio-cultural factors that enter into the perception of the treatment and adherence to it.
In these countries, where over 9000 new cases of tuberculosis are diagnosed every year, access to free treatment is provided by the National Tuberculosis Control Programme through government health districts (2). However, nearly 30 % of patients do not follow this treatment correctly and scarcely 60% of people ill from the disease receiving a prescription manage to be cured. What are the reasons for this? Long distances from the health centres are among the first difficulties encountered. However, insufficient emphasis on listening to patients, counselling and information provision by health district personnel, associated with shortfalls in following up the DOT strategy also combine to discourage patients from taking the treatment right to the end of the prescribed course.
In this context, the researchers looked simultaneously into the relations between health-care staff and the tuberculosis patients, the perception of the disease and its treatment in the community in which they live. They thus proposed action consisting of four major strands: training of health-care personnel, aiming to improve communication and support to patients, the decentralization of access to treatment to offer availability at local medical posts by involving health personnel who are attached to these, reinforcement of the DOT strategy by allowing patients to choose their supporter from among the staff or from within their community (imam, family relation, teacher...) and improved coordination of the activity of medical posts from the district centres.
To test the effectiveness of this action, a randomized controlled clinical trial was run between June 2003 and January 2005 on 16 district health centres and 1522 patients, who were separated at random into two groups. The first group was treated according to the action procedure proposed by the researchers, the second according to the usual strategy of the National Tuberculosis Control Programme (control group). After one year, a distinct improvement in adherence to treatment was observed in the first case: the rate of cure from tuberculosis rose by 20% and the proportion of patients defaulting fell by two-thirds (from 16.8 to 5.5 %).
The training of health-care personnel, communication to inform patients and make them aware of their responsibilities, just as the taking into account of the local, social and cultural context of communities, clearly appear to be essential factors for the sound running of the therapy and the long-term efficacy of actions geared to tuberculosis control. This action strategy, by improving adherence to treatment and the rate of successful patient outcomes, should thus help restrict the spread of the disease and prevent the arrival on the scene of new resistant strains of bacteria. Research work is continuing, in the form of a trial conducted by the IRD in conjunction with WHO, aiming to make available a shorter, 4-month treatment which could lead to still a further improvement of adherence and outcome results.
(1) This research involved IRD research unit UR 145 (Programme Tuberculose), the London School of Hygiene and Tropical Medicine, the Programme National de Lutte anti-tuberculeuse of Senegal, and the International Union against Tuberculosis and Lung Diseases, based in Paris.
(2) The standard treatment recommended here lasts 8 months: a 2-month phase to attack the disease by combining rifampicin, isoniazid, pyrazinamid and ethambutol followed by stabilizing phase of 6 months involving combined treatment with isoniazid and ethambutol.
Sylla Thiam, Andrea M. LeFevre, Fatoumata Hane, Alimatou Ndiaye, Fatoumata Ba, Katherine L. Fielding, Moustapha Ndir, Christian Lienhardt - Effectiveness of a Strategy to Improve Adherence to Tuberculosis Treatment in a Resource-Poor Setting. A Cluster Randomized Controlled Trial, Journal of American Medical Association (JAMA), January 24/31, 2007, vol. 297, n°4.
Fatoumata Hane, Sylla Thiam, Abdou Salam Fall, Laurent Vidal, Awa-Hélène Diop, Moustapha Ndir, Christian Lienhardt - Identifying barriers to effective tuberculosis control in Senegal: year anthropological approach. International Journal of Tuberculosis and Lung Diseases. In press, 2007, vol 11.
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