Interventions for Tuberculosis Control and Elimination 2002

made here to provide a comprehensive list of all of the trials, the best
known have been selected to review the efficacy that preventive chemotherapy
has offered in randomized controlled clinical trials in various settings.
In order to provide comparable results, Wald 95% confidence intervals
731 were calculated for all trial efficacy estimates, unless (in some recent
publications) the authors provided adjusted risk ratios or provided insufficient
data to recalculate confidence intervals. In this case, the confidence
intervals provided by the authors were used.
Prevention of disease in tuberculin skin test reactors
Persons who react to tuberculin, but whose acquisition of tuberculous infection
lies in the remote past, have a relatively small annual risk of progression
to clinically active tuberculosis compared with persons who have
recently acquired infection. 1 While the exact point of acquisition of infection
is rarely known for an individual, several studies have been conducted
among patients whose tuberculous infection has been unlikely, to have been
of recent origin on average (wide spread of acquisition points in time).
The first point of interest is the efficacy of preventive chemotherapy in providing
protection against progression to tuberculosis during, and only during,
the length of treatment. Three of the four trials for which such information
is available used isoniazid for twelve months 641,872-874 , and in one it
was given for nine months. 875 The results obtained by the end of the treatment
period are summarized in figure 77.
Mental patients
Contacts of
known cases
Alaskan villagers
Greenland villagers
0 50 70 90
Protection (%) (log scale)
Figure 77. Protection from isoniazid preventive therapy against tuberculosis among
tuberculin skin test reactors during the year of treatment. 641,872-875
128