Global trends in resistance to antituberculosis drugs

Background: Data on global trends in resistance to antituberculosis drugs a re lacking. Methods: We expanded the survey conducted by the World Health Organization and the International Union against Tuberculosis and Lung Disease to assess trends in resistance to antituberculosis drugs in countries on six contine nts. We obtained data using standard protocols from ongoing surveillance or from surveys of representative samples of all patients with tuberculosis. The standard sampling techniques distinguished between new and previously t reated patients, and laboratory performance was checked by means of an inte rnational program of quality assurance. Results: Between 1996 and 1999, patients in 58 geographic sites were survey ed; 28 sites provided data for at least two years. For patients with newly diagnosed tuberculosis, the frequency of resistance to at least one antitub erculosis drug ranged from 1.7 percent in Uruguay to 36.9 percent in Estoni a (median, 10.7 percent). The prevalence increased in Estonia, from 28.2 pe rcent in 1994 to 36.9 percent in 1998 (P=0.01), and in Denmark, from 9.9 pe rcent in 1995 to 13.1 percent in 1998 (P=0.04). The median prevalence of mu ltidrug resistance among new cases of tuberculosis was only 1.0 percent, bu t the prevalence was much higher in Estonia (14.1 percent), Henan Province in China (10.8 percent), Latvia (9.0 percent), the Russian oblasts of Ivano vo (9.0 percent) and Tomsk (6.5 percent), Iran (5.0 percent), and Zhejiang Province in China (4.5 percent). There were significant decreases in multid rug resistance in France and the United States. In Estonia, the prevalence in all cases increased from 11.7 percent in 1994 to 18.1 percent in 1998 (P <0.001). Conclusions: Multidrug-resistant tuberculosis continues to be a serious pro blem, particularly among some countries of eastern Europe. Our survey also identified areas with a high prevalence of multidrug-resistant tuberculosis in such countries as China and Iran. (N Engl J Med 2001;344:1294-303.) Cop yright (C) 2001 Massachusetts Medical Society.