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AbstractThe objective of this study was to analyze factors associated with isoniazid-resistance among pulmonary tuberculosis patients in Northern Thailand. Data was obtained from 36 hospitals in the area under supervision of The Office of Communicable Disease Prevention and Control Region 10, Chiang Mai, in which information of tuberculosis patients who had received isoniazid and was tested for resistance to the drug between 2003 and 2007 was collected. There were 504 patients who could be included in the analysis. These patients were divided into 2 groups through matching method (1:3) by using genders and age variables. There were 126 patients who were put into a “Case” group where patients showed resistance to isoniazid and 378 patients who were put into a “Control” group where patients showed no signs of resistance to the drug. Factors associated with isoniazid-resistance were assessed using univariate and multivariate conditional logistic regression analyses. It was found that 23.0% of patients in the case group and only 7.4% in the control group were relapsed patients. And, of these relapsed patients, the percentages of patients who had received treatment more than twice before were 27.6 and 10.7, respectively. After a univariate analysis, the following statistically significant factors contributing to the drug resistant condition were found: 1) type of patient 2) drug resistant tuberculosis mycobacterium infection 3) nontuberculoses mycobacterium infection 4) type of standard drugs treatment used, and 5) drugs’ side effect. When other variables were controlled, it was found that relapsed patient is 5.5 times more likely to be drug resistant than new patient. (95% confidence interval: 2.3–13.0). The results of this research indicated that doctors and healthcare personnel should be aware of whether the patient is a relapsed or a new patient and to closely monitor patient’s reaction to the treatment.

AbstractThe objective of this study was to analyze risk factors of drug resistance in pulmonary tuberculosis patients with relapse. A total of 196 pulmonary tuberculosis patients with relapses from 2001 to 2005 were referred to the Office of Communicable Disease Prevention and Control Region 10, Thailand. Data were collected from the tuberculosis chart. Classification tree and logistic regression analysis were used to determine the risk factors of drug resistance. According to the optimal classification tree, three risk factors were determined: number of previous TB treatments, weight at baseline and shortness of breath. In the logistic regression model, four risk factors were found to be significant: underlying disease (odds ratio (OR) = 2.3; 95% CI, 1.1–4.4); cavity (OR = 2.8; 95% CI, 1.2–6.9); number of previous TB treatments ≥ 2 times (OR = 2.7; 95% CI, 1.0–7.1); and age ≥ 65 years (OR = 2.4; 95% CI, 1.1–5.1). However, the logistic regression model and optimal tree had low sensitivity, possibly due to the lack of potential risk factors that were not considered in this study. The findings underscore that the treatment of relapse patients, those with at least two previous TB treatments should be subjected to a drug susceptibility test so that an appropriate form of treatment can be prescribed.