Dear Editor

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 2 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 been recently transmitted has been estimated at 14.4 %.[3] This is very low when compared to 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 increase incidence of tuberculosis in London.[5]

Randomised controlled trials have shown that direct observation by either a health care 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 (see table). 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 targetted 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 tailored to his or her needs.

Â	London (current)	New York (1992-4)
Incidence of TB	35 per 100,000 (Newham 110 per 100,000)	46 per 100,000 (Central Harlem 222/100.000)
Cost of TB services	£8 million [14] (£34.2 million)[15]*	>$400 million [2]
DOT strategy	Selective	Universal â€
Completed treatment	87% ‡	  <_50 _2="_2" font="font">
Relapsed TB	6-8% ‡	 51% [2]
HIV co-infection	14% [16]	38% [2] §
Multidrug resistant TB	1.7% [1]	19% [17]
Recent transmission (estimate from molecular epidemiology)	14.4% [3]	48% [4]
Cause of increase in TB	New entrants (Foreign-born) Elderly women HIV (11%) [16]	HIV [2] Nosocomial Homeless Foreign-born

*   estimated as £6k per TB patient and £60k per MDRTB treated
†   actually around 30% were receiving DOT
‡   unpublished data, North East London TB Network office, London TB Group and King’s College Hospital, South East London
§   38% of all, 72% of those tested

References

(1) Djuretic T, Herbert J, Drobniewski F, Yates M, Smith EG, Magee JG, et al. Antibiotic resistant tuberculosis in the United Kingdom: 1993-1999. Thorax 2002;57(6):477-82.

(2) Frieden TR, Fujiwara PI, Washko RM, Hamburg MA. Tuberculosis in New York City: turning the tide. N Engl J Med 1995;333(4):229-33.

(3) Maguire H, Dale JW, McHugh TD, Butcher PD, Gillespie SH, Costetsos A, et al. Molecular epidemiology of tuberculosis in London 1995-7 showing low rate of active transmission. Thorax 2002;57(7):617-622.

(4) Geng E, Kreiswirth B, Driver C, Li J, Burzynski J, DellaLatta P, et al. Changes in the transmission of tuberculosis in New York City from 1990 to 1999. N Engl J Med 2002;346(19):1453-8.

(5) Rose AM, Watson JM, Graham C, Nunn AJ, Drobniewski F, Ormerod LP, et al. Tuberculosis at the end of the 20th century in England and Wales: results of a national survey in 1998. Thorax 2001;56(3):173-9.

(6) Zwarenstein M, Schoeman JH, Vundule C, Lombard CJ, Tatley M. Randomised controlled trial of self-supervised and directly observed treatment of tuberculosis. Lancet 1998;352(9137):1340-3.

(7) Walley JD, Khan MA, Newell JN, Khan MH. Effectiveness of the direct observation component of DOTS for tuberculosis: a randomised controlled trial in Pakistan. Lancet 2001;357(9257):664-9.

(8) Kamolratanakul P, Sawert H, Lertmaharit S, Kasetjaroen Y, Akksilp S, Tulaporn C, et al. Randomized controlled trial of directly observed treatment (DOT) for patients with pulmonary tuberculosis in Thailand. Trans R Soc Trop Med Hyg 1999;93(5):552-7.

(9) Burman WJ, Cohn DL, Rietmeijer CA, Judson FN, Sbarbaro JA, Reves RR. Noncompliance with directly observed therapy for tuberculosis. Epidemiology and effect on the outcome of treatment. Chest 1997;111(5):1168-73.

(10) Volmink J, Garner P. Systematic review of randomised controlled trials of strategies to promote adherence to tuberculosis treatment. Bmj 1997;315(7120):1403-6.

(11) Volmink J, Matchaba P, Garner P. Directly observed therapy and treatment adherence. Lancet 2000;355(9212):1345-50.

(12) Bothamley GH, Rowan JP, Griffiths CJ, Beeks M, McDonald M, Beasley E, et al. Screening for tuberculosis: the port of arrival scheme compared with screening in general practice and the homeless. Thorax 2002;57(1):45-9.

(13) Lalvani A, Pathan AA, Durkan H, Wilkinson KA, Whelan A, Deeks JJ, et al. Enhanced contact tracing and spatial tracking of Mycobacterium tuberculosis infection by enumeration of antigen-specific T cells. Lancet 2001;357(9273):2017-21.

(14) NHS_Executive. Tuberculosis Control in London - the need for change. A report for the Thames Regional Directors of Public Health. London. 1998.

(15) White VL, Moore-Gillon J. Resource implications of patients with multidrug resistant tuberculosis. Thorax 2000;55(11):962-3.

(16) Rose AM, Sinka K, Watson JM, Mortimer JY, Charlett A. An estimate of the contribution of HIV infection to the recent rise in tuberculosis in England and Wales. Thorax 2002;57(5):442-5.

(17) Frieden TR, Sterling T, Pablos-Mendez A, Kilburn JO, Cauthen GM, Dooley SW. The emergence of drug-resistant tuberculosis in New York City. N Engl J Med 1993;328(8):521-6.