Identification of risk factors for MDR TB among patients with pulmonary tuberculosis : a case control study in Karachi, Pakistan /

Date of Award


Document Type


Degree Name

Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)


Community Health Sciences


Among first line anti-TB drugs, Rifampicin (RMP) and Isoniazid (INH) are considered the most potent available drugs. Drug resistance against anti-TB drugs and multi-drug resistance - MDR TB (a resilient form of TB - defined as resistance to at least INH and RMP) have lower cure rates than drug-susceptible TB. MDR TB accounts for up to l4%o of the world's total TB cases and with treatment cost being almost 100 times more than treating a susceptible TB patient it is imperative that this problem be addressed on priority basis. Risk factors identification is important from a public health perspective, because it helps us in devising intended interventions and preventive strategies. Recognition of risk factors for MDR TB may help us in formulating prevention strategies against this aggravating public health issue of our country. Therefore our objective was to identify risk factors for multi-drug resistance among culture diagnosed patients of pulmonary tuberculosis in Karachi, Pakistan. Data collection for the case control study was conducted from July 2001 to April 2002 in three tertiary care hospitals and homes of subjects in Karachi city. Cases were ≥ 15-yearold sputum culture and sensitivity diagnosed MDR TB patients. Controls were ≥ 15-yearold, sputum culture & sensitivity diagnosed (during the same time period as of cases) drug susceptible pulmonary tuberculosis patients. Eligible subjects were identified from the records and in-patients of the three hospitals. Resident subjects of Karachi were accessed at homes, while in-patients were interviewed in the respective hospitals. Calculated sample size was 121 cases and242 controls, which could not be attained in the stipulated time period and a final sample of 50 cases and 75 controls was achieved. Mean age of cases was 31.5 years (SD 12.0 years) while for controls it was 44.0years (SD 19.6 years). Males and females were equally represented among cases. Sindhi was the most commonly (34%) spoken language among cases in comparison to an Urdu speaking majority (37.3%) among controls. Forty eight percent of cases and 26.7Vo of controls were illiterate. Our final multivariate model showed significant associations with MDR TB for independent variables of 15-25 years age group, male gender, Sindhi as mother tongue, illiteracy and education of l-5 years. On the basis of significance, TB treatment taken in the past (aOR = 4.2, 95% C.l 1.1 - 15.4) and presence of a TB patient in the household (aOR = 3.I, 95% C.I 1.2 - 8.3) were also included in our final model. We have identified modifiable risk factors of past TB treatment, presence of TB patient in household and illiteracy. Emphasis on health education and appropriate caring of MDR TB patients is required. This may involve better health education to patients and caregivers, better prescribing practices and ensuring compliance with TB treatment for reducing the increased risk of MDR TB. We recommend further research to assess true burden of MDR TB in our setting and to estimate the anticipated public health impact of any interventions directed towards reducing these risk factors.

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