Prevalence of multi-drug resistant tuberculosis in Karachi, Pakistan: identification of at risk groups.

Multidrug-resistant tuberculosis (MDR-TB) is a possible threat to global tuberculosis control. Despite a disease prevalence of 263/100 000 population Pakistan lacks information on prevalence of drug resistant TB. Our objective was to estimate prevalence of MDR and associated risk factors in patients with pulmonary tuberculosis in Karachi. Six hundred and forty consenting adult patients were enrolled from field clinics from July 2006 to August 2008 through passive case finding. Prevalence of MDR-TB with 95% confidence interval (CI) was calculated with Epi-Info. Logistic Regression analyses were performed for risk factors associated with MDR. Overall MDR rate was 5.0%, 95% CI: 3.3-6.6% (untreated 2.3%, treated 17.9%). Mean age was 32.5 (+/-15.6) years and there were 292 (45.6%) females and 348 (54.4%) males. Factors independently associated with MDR were: female gender (OR 3.12; 95% CI: 1.40-6.91), and prior history of incomplete treatment (OR 10.1; 95% CI: 4.71-21.64). Ethnic groups at higher risk for MDR included Sindhis (OR 4.5; 95% CI: 1.42-14.71) and Pashtoons (OR 3.6, 95% CI: 1.12-11.62). This study reports an overall MDR rate of 5.0% in our study population. It further highlights the need for MDR prevention through re-focusing Directly Observed Treatment, Short-course DOTS delivery with emphasis on women and certain high risk sub groups.