[Clinical epidemiology and treatment of tuberculosis in elderly patients]

In developed countries the incidence of tuberculosis is higher in patients aged 65 and over than in any other age group, with the exception of HIV positive subjects. This high incidence is a consequence of the very high rate of infection in our countries in the first part of the century, and of the diminished efficiency of the aging immune system. In this age group, most cases of tuberculosis are reactivations of dormant mycobacteria. However, the possibility of a newly acquired infection must be kept in mind, especially in institutionalized patients. The clinical presentation is often insidious and non-specific, as is the radiological presentation (i.e. infiltrates in middle or lower lobes); the large number of cases discovered at autopsy illustrates the difficulty of clinical diagnosis. Extra-thoracic involvement is less frequent than in younger adults (15% of cases). Mortality is high, even in treated patients, and increases with age. The frequency of drug-induced hepatitis under tuberculostatic treatment increases with age: signs of hepatic toxicity should be monitored regularly; furthermore, compliance with treatment may be jeopardized by cognitive impairment: directly observed treatment should be set up when there is the slightest doubt as to compliance. Prophylactic treatment with isoniazid is indicated in recent tuberculin converters (after exclusion of active disease), in patients with diabetes or on immunosuppressive therapy, and in patients with radiological fibrotic lesions without serious co-morbidities. In institutionalized subjects regular tuberculin testing is warranted to detect nosocomial infection.