RISK-FACTORS FOR THE DEVELOPMENT OF NONRESPONSE TO FIRST-LINE TREATMENT FOR TUBERCULOSIS IN SOUTHERN VIETNAM

Background. Acquired resistance to standard chemotherapy for tuberculo sis (TB) is an increasing problem worldwide. Vietnam has one of the hi ghest incidences of TB and also has a large population of potential mi grants to other countries. Since 1979 the international Organisation f or Migration (IOM) has been running a supervised programme of TB treat ment for intending migrants from Vietnam where few facilities for bact eriological culture and sensitivity testing exist, This study aimed to assess the most important factors for predicting non-response to firs t-line treatment as treatment starts and whether any further indicator s occur during the course of treatment which may enable more accurate prediction of non-response. Methods. In all, 130 subjects failing to r espond to first-line therapy (cases) between 1990 and 1995 were compar ed with 673 subjects who responded to therapy (controls) on various de mographic and clinical characteristics using logistic regression to cr eate a prognostic index. Variables analysed included the patient histo ry of past TB treatment, weight, age, sex and radiological and bacteri ological findings, All subjects also tested negative for HIV status. R esults. The chief markers of successful response were x-ray signs and degree of sputum smear positivity, These markers provided a prognostic index with an optimal cutoff providing about 70% sensitivity and 80% specificity. Incorporating further measures obtained through the first 3 months of treatment improved the sensitivity to 80%. Conclusion. Wh ile this study enabled prediction of the majority of subjects failing to respond to first-line therapy, other factors need to be assessed be fore recommendations for altering treatment regimens can be made, The prognostic index could be useful in assessing subjects for closer supe rvision.