Extension of the intensive phase reduces unfavourable outcomes with the 8-month thioacetazone regimen.
METHODS
Damien Foundation tuberculosis (TB) control projects in Bangladesh.


OBJECTIVE
To assess the effectiveness of a 1-month extension of the intensive phase for smear-positives at 2 months of an 8-month regimen with a continuation phase consisting of isoniazid (INH) and thioacetazone (Th).


METHODS
A prospective study of two cohorts of newly registered smear-positive cases, with extension of the intensive phase for the control cohort, but not for the study cohort. Culture and drug susceptibility testing (DST) of smear-defined failures and relapses and of random samples of new cases.


RESULTS
Among 8230 study patients (86.7% 2-month conversion) and 7206 controls (83.4% conversion), smear-defined failure or relapse outcome was 3.0% for 2-month smear-negatives vs. 3.1% for 2-month smear-positives with extension (non-significant, NS), and 8.2% for 2-month smear-positives with no extension (P < 0.00001). Culture-confirmed failure and relapse reached 1.9% in 2-month smear-negatives and 1.6% (NS) in 2-month smear-positives with vs. 3.7% (P < 0.001) in 2-month smear-positives with no extension. The relative risk (RR) of non-extension in 2-month smear-positives was 2.4 (cultures) to 2.7 (smears). The same RR and borderline significance was found for non-extension of patients with pan-susceptible strains.


CONCLUSIONS
Extension of the intensive phase considerably reduces failures and relapses with a weaker regimen in patients smear-positive at 2 months. Its effectiveness may vary with extent of initial drug resistance vs. power of the regimen.
Van Deun
A
A
Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium. avdeun@itg.be
Aung
K J M
KJ
Hamid Salim
M A
MA
Ali
M A
MA
Naha
M S
MS
Das
P K
PK
Hossain
M A
MA
Declercq
E
E
D000995:Antitubercular Agents / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology; D013828:Thioacetazone / Q000627:therapeutic use*; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000382:microbiology
D000995:Antitubercular Agents; D013828:Thioacetazone; D007538:Isoniazid