Controlled clinical trial of four short-course regimens of chemotherapy for two durations in the treatment of pulmonary tuberculosis. Second report. Third East African/British Medical Research Council Study.

Four short-course chemotherapy regimens for pulmonary tuberculosis have been compared: (1) streptomycin, isoniazid, rifampicin and pyrazinamide daily for 2 months followed by daily thiacetazone plus isoniazid; (2) the same 4 drugs daily for 1 month followed by thiacetazone plus isoniazid; (3) the same 4 drugs daily for 1 month followed by twice-weekly streptomycin, isoniazid and pyrazinamide; (4) the first regimen but without pyrazinamide in the initial intensive phase. Each regimen was given for 6 and 8 months and patients were followed up to 30 months. When given for 6 months the regimen with a 2-month 4-drug intensive phase had a bacteriological relapse rate of 13% and when given for 8 months there were no relapses. When pyrazinamide was omitted in the first 2 months the relapse rates were 18% for the 6-month and 6% for the 8-month series. The regimen with the 4-drug initial phase shortened to 1 month had relapse rates of 18% and 7% respectively if the continuation phase was thiacetazone plus isoniazid. However, the relapse rates were lower, 9% and 2% respectively, when the continuation phase was twice-weekly streptomycin, isoniazid and pyrazinamide.