Study designs of evaluations included in the review
Randomised controlled trials (RCTs) and quasi-RCTs were eligible for inclusion. The author stated that studies using other research methods were assessed for inclusion in the review as a narrative summary. All of the included studies were cohort studies.
Specific interventions included in the review
For new cases, SCC regimens consisting of four drugs during the initial phase (2 months) followed by two drugs during the continuation phase (4 months) were eligible for inclusion. For re-treatment cases, SCC regimens consisting of five drugs during the initial phase followed by three drugs during the continuation phase, with a total treatment duration of 8 months, were eligible for inclusion. Both daily and intermittent regimens were eligible for inclusion. Some of the included studies used World Health Organization (WHO) recommended treatment regimens. A three-drug treatment combination regimen was used during the initial phase in some studies and during the continuation phase only in one study. Some studies used the intermittent regimen. Some studies assessed directly observed therapy.
Participants included in the review
Patients with pulmonary TB, including new patients and re-treatment patients, aged at least 16 years with positive growth on culture of Mycobacterium tuberculosis and susceptibility test results were eligible for inclusion. Most of the studies included civilian TB patients; however, one study included prisoners and one study included gold miners infected with the human immunodeficiency virus. The majority of the included studies were conducted in Asia, while the others were conducted in Europe, North America and South Africa; one study was conducted in six different countries.
Outcomes assessed in the review
The outcomes of interest were results of susceptibility testing for first-line anti-TB drugs and six standardised treatment outcomes of the WHO:
cure (defined as a patient who is smear negative at, or one month prior to, completion of treatment and on at least one previous occasion);
treatment completed (defined as a patient who has completed treatment but without proof of cure);
treatment success (obtained by adding the percentage of cure cases and the percentage of cases in whom treatment was completed);
treatment failure (defined as a patient who remains or becomes smear-positive again at 5 months or later during treatment);
died (defined as a patient who dies for any reason during the course of therapy);
treatment interrupted or default (defined as a patient whose treatment was interrupted for at least 2 months);
transfer out (defined as a patient who has been transferred to another reporting unit and for whom the treatment outcome is not known).
Most of the included studies assessed outcomes at the end of the treatment period.
How were decisions on the relevance of primary studies made?
Two reviewers independently assessed studies for inclusion in the review, and any disagreements were resolved through discussion with a third reviewer.