Controlled trial of 6- and 9-month regimens of daily and intermittent streptomycin plus isoniazid plus pyrazinamide for pulmonary tuberculosis in Hong Kong.

A comparison has been made between 6- and 9-month regimens of streptomycin, isoniazid and pyrazinamide given daily, 3 times a week or twice a week from the start of chemotherapy, in the treatment of newly-diagnosed, smear-positive, pulmonary tuberculosis in Chinese patients. At 6 months the twice-weekly regimen was marginally inferior in that 5 (4 per cent) of 126 patients with drug-sensitive strains pretreatment had an unfavourable bacteriological status compared with only 2 (1 per cent) of 141 on the 3 times weekly and none of 137 of the daily regimen. Of a total of 211 patients treated for 9 months, only 1 of 74 on the twice-weekly regimen relapsed bacteriologically between 6 and 9 months. The bacteriological relapse rates in the first 6 months of follow-up after 6 months' chemotherapy were 13 per cent on the daily, 16 per cent on the 3 times weekly, and 18 per cent on the twice-weekly regimen, and after 9 months' chemotherapy they were 3 per cent, 4 per cent and 4 per cent respectively. All 33 relapses were with strains sensitive to isoniazid and streptomycin, and 76 per cent of them occurred in the first 3 months after the end of chemotherapy. Although patients with drug-resistant strains pretreatment fared less well, about two-thirds had a favourable bacteriological status at 6 months, and all 3 regimens given for 9 months had low relapse rates. The implications of these findings are discussed.