A chest X-ray may not be needed in resource-limited settings before administering a course of isoniazid to prevent the development of active tuberculosis, according to doctors from Botswana writing this week in The Lancet.
The World Health Organisation currently recommends that all patients with HIV should receive a chest X-ray to rule out the presence of active TB where symptoms are not present. Treatment of TB with a single drug leads to drug resistance, and the WHO protocol is designed to prevent the administration of isoniazid monotherapy to people with active TB.
However, physicians in Botswana argue that routine chest X-ray should not be required before administering isoniazid prophylaxis to people with HIV. They assessed 935 individuals with HIV infection referred to a treatment centre from a network of clinics and testing centres, 692 of whom had no signs or symptoms of active tuberculosis. Of these, 99% agreed to have a chest X-ray, but 83 never went for an X-ray, a further 34 never returned for the results and nine started isoniazid without an X-ray, in error.
Of the remaining 560 who completed the process, 96% (536) of chest X-rays were normal. Only one patient could be diagnosed with TB on the basis of a chest X-ray; the remaining 23 had chest X-rays that were interpreted as non-specific pneumonitis (mycobacterial cultures were not carried out to confirm this diagnosis.
The authors say that the chest X-ray programme appeared to contribute to a high number of patients lost to follow up (18%) for the sake of detecting one case of active tuberculosis.
An accompanying commentary by Drs. Chifume Chintu and Peter Mwaba of the University of Zambia School of Medicine argues that WHO needs to review its recommendation of chest X-rays and produce evidence to justify the use of this costly intervention. They note that extrapulmonary tuberculosis (more common in people with HIV than the rest of the population) would not be detected by a chest X-ray.
Barudi Mosimaneotsile, author of the Botswana study, concludes: "A screening chest radiograph should not be required routinely for asymptomatic people taking isoniazid as preventive treatment in settings able to screen for signs and symptoms of tuberculosis."
References
Chintu C, Mwaba P. Is there a role for chest radiography in identification of asymptomatic tuberculosis in HIV-infected people? The Lancet 362: 1516, 2003.
Mosimaneotsile B et al. Value of chest radiography in a tuberculosis prevention programme for HIV-infected people, Botswana. The Lancet 362: 1551-2, 2003.