Interventions for Tuberculosis Control and Elimination 2002

Case holding
Prescription of an adequate course of treatment is not sufficient; it must be
ensured that the prescribed medications are also actually taken until the
successful, curative completion of therapy.
Directly observed therapy
Ensuring regularity of treatment is the key to timely completion of therapy
and the prevention of acquisition of drug resistance. The problems with
self-administered chemotherapy in ensuring regular adherence have long
been recognized, 279 and to ascertain the efficacy of regimens in clinical trials,
direct observation of drug intake during part or the entire course of
treatment has thus been standard in many investigations. 122
Directly observed therapy refers to treatment where a qualified person
(usually, but not always, 626 a health care worker) ensures that the prescribed
medications are taken by observing the patient ingesting them. 627 Directly
observed ambulatory therapy has its evidence base in studies in Chennai
(formerly Madras) and Hong Kong, 628 and the recognition of the need for
alternatives to costly hospitalization.
Directly observed therapy might be conceived of as a coercive procedure,
but it may also help to strengthen the relationship between patient
and health care worker. 629 If this does not occur, then directly observed
therapy may not achieve an increase in the proportion of patients completing
therapy. 630
The major effects of directly observed therapy that might be expected
are a reduction in the risk of acquiring drug resistance and in the frequency
of relapse following completion of chemotherapy, as convincingly demonstrated
in a study in the United States (figure 52). 631
Can emergence of drug resistance be outpaced
in a national tuberculosis program?
Strains resistant to isoniazid should have a comparative advantage, as patients
harboring such a strain will, on average, be transmitters for a longer period
of time than patients with a fully susceptible strain. Thus, one would expect
an increase in the prevalence of primary resistance to isoniazid. This is,
however, not the case in well-managed programs. 632,633 Some studies sug-
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