Low failure rate in standardised retreatment of tuberculosis in Nicaragua:patient category, drug resistance and survival of 'chronic' patients

SETTING: IUATLD collaborative programme, Nicaragua. OBJECTIVE: To analyse reported trends in the retreatment failure rate (2SRH ZE/1RHZE/5R(3)H(3)E(3)), and assess demographic characteristics, drug resis tance and survival in patients who fail retreatment. DESIGN: A retrospective, descriptive study. Reports from 1988-1996 were ana lysed and records of 69 patients who failed retreatment were reviewed. RESULTS: The treatment success rate in new cases improved from 71% in 1988- 1991 to 79% in 1992-1996, the default rate decreased from 16% to 10%, and t he failure rate remained stable at 2-3%. The proportion of previously treat ed patients among all smear-positives decreased from 20% to 15%. In retreat ment patients the failure rate declined from 6.6% to 4.3% and the average a nnual number of failures from 24 to 13. Tn 1992-1996, 64 patients, 0.8% of new smear-positive cases treated during this period, failed retreatment; th e corresponding figures for 1988-1991 are 95 and 1.6%. Among 69 retreatment failure cases reviewed, there was male predominance and increasing age dur ing the study period. Drug susceptibility results were available for 38, of whom 89% were resistant to isoniazid and rifampicin. The median survival o f patients after failure was 3.9 years. CONCLUSION: Treatment results improved over the study period. The proportio n of patients on retreatment out of all smear positives treated decreased, as did the absolute number of failures and the retreatment failure rate. De velopment of multidrug resistance has been largely prevented in Nicaragua; the low failure rate justifies the continued use of the standardised retrea tment regimen.