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Supervised drug taking is frequently seen as the answer to rising levels of tuberculosis. Djuretic et al advocate directly observed therapy (DOT) for all patients with smear-positive pulmonary tuberculosis in London.1 At first sight the experience of instituting DOT in New York City appears especially impressive, with a 21% reduction in case rates and 39% decrease in drug resistant isolates. However, these reductions occurred at the same time as close attention was paid to drug regimens, the use of drug combinations, increased staffing levels, and the payment of incentives combined with the threat of imprisonment for persistent defaulters. The cost was phenomenal.2
The proportion of cases of tuberculosis in London that have recently been transmitted has been estimated at 14.4%.3 This is very low compared with 48% in New York City.4 The decreased incidence of tuberculosis in New York City was achieved entirely within groups where recent transmission was suspected. Over the same time period there was a 22% increased incidence among foreign born persons. Such people have contributed most to the recent increased incidence of tuberculosis in London.5
Randomised controlled trials have shown that direct observation either by a healthcare worker or family member does not improve treatment completion rates when compared with self-administered treatment.6–8 Furthermore, even with supervised drug taking, patients can still fail to complete treatment. In one study in Denver, 18% missed two consecutive weeks of treatment, continued treatment for more than 30 days beyond the expected date of completion because of defaulting, or were imprisoned as a threat to public health.9 In a review of randomised controlled trials to promote adherence, monetary incentives, home visits and attentive staff were important elements of successful programmes.10,11
The situation in London clearly requires action. The data, however, suggest different approaches to those taken in New York City (table 1). New entrant screening deserves greater attention, and a heightened awareness of tuberculosis in primary care could complement the current system.12 The tuberculin skin test has a poor specificity and sensitivity and we should investigate newer methods of diagnosing those patients with latent tuberculosis who have a high probability of progressing to disease.13 We should maintain our vigilance to prevent active transmission by treating those with infectious, smear positive pulmonary tuberculosis rapidly and effectively. This can be complemented with well targeted contact tracing. Selective DOT is a part of this programme, but we would emphasise that each patient should be treated as an individual and treatment should be tailored to his or her needs.
Epidemiology and treatment of TB in London (UK) and New York (USA)