Ethambutol plus isoniazid compared with rifampicin plus isoniazid in antituberculosis continuation treatment.

Patients with bacteriologically positive pulmonary tuberculosis were treated initially for an average of three and a half months with isoniazid, rifampicin, and ethambutol and then a total of one year's treatment was completed with either rifampicin plus isoniazid (R+I) or with ethambutol plus isoniazid (E+I). 63 patients in each continuation group were followed up for at least one year, and no relapses occurred. Continuation treatment with E+I was as effective and acceptable as that with R+I and was much less costly.