Preventive therapy for tuberculosis in Western Australia

SETTING: State Tuberculosis Control Programme, Western Australia. OBJECTIVE: To ascertain baseline information, applicability and efficacy of preventive therapy for tuberculosis (TB) under indirectly supervised treat ment in Western Australia. DESIGN: Retrospective analyses of records of persons with TB infection who were prescribed preventive therapy for the period 1993-1996 inclusive, usin g simple descriptive statistics. RESULTS: Preventive therapy was given to 411 persons after screening for TB due to on-arrival migrant surveillance (269), contact tracing (59), tuberc ulin surveys (59) and other reasons (24), Six-month isoniazid monotherapy ( HMT) was prescribed for 403 and multidrug regimens for the remaining eight. Excepting 34 whose compliance was unknown, varying degrees of treatment no nadherence were found in 90 (24%) of the remaining 369 persons given HMT, i ncluding 36 (10%) with under five months of total medication. Minor adverse drug effects occurred in 32 (9%) subjects and contributed to the non-adher ence in 23 of these. One person has since developed active TB. CONCLUSIONS: Preventive therapy in Western Australia conformed to generally accepted guidelines. Varying degrees of non-adherence to HMT occurred in 2 4% of persons, but 90% completed adequate therapy under indirect supervisio n, Non-adherence is significantly related to adverse drug effects.