Epidemiology of antituberculosis drug resistance (the Global Project on Anti-tuberculosis Drug Resistance Surveillance): an updated analysis.

BACKGROUND The burden of tuberculosis is compounded by drug-resistant forms of the disease. This study aimed to analyse data on antituberculosis drug resistance gathered by the WHO and International Union Against Tuberculosis and Lung Disease Global Project on Anti-tuberculosis Drug Resistance Surveillance. METHODS Data on drug susceptibility testing for four antituberculosis drugs--isoniazid, rifampicin, ethambutol, and streptomycin--were gathered in the third round of the Global Project (1999-2002) from surveys or ongoing surveillance in 79 countries or geographical settings. These data were combined with those from the first two rounds of the project and analyses were done. Countries that participated followed a standardised set of guidelines to ensure comparability both between and within countries. FINDINGS The median prevalence of resistance to any of the four antituberculosis drugs in new cases of tuberculosis identified in 76 countries or geographical settings was 10.2% (range 0.0-57.1). The median prevalence of multidrug resistance in new cases was 1.0% (range 0.0-14.2). Kazakhstan, Tomsk Oblast (Russia), Karakalpakstan (Uzbekistan), Estonia, Israel, the Chinese provinces Liaoning and Henan, Lithuania, and Latvia reported prevalence of multidrug resistance above 6.5%. Trend analysis showed a significant increase in the prevalence of multidrug resistance in new cases in Tomsk Oblast (p<0.0001). Hong Kong (p=0.01) and the USA (p=0.0002) reported significant decreasing trends in multidrug resistance in new cases of tuberculosis. INTERPRETATION Multidrug resistance represents a serious challenge for tuberculosis control in countries of the former Soviet Union and in some provinces of China. Gaps in coverage of the Global Project are substantial, and baseline information is urgently required from several countries with high tuberculosis burden to develop appropriate control interventions.