MDR Need Greatest in China
Finding an effective treatment for MDR tuberculosis is especially important in China, which has the greatest number of cases in the world, Yanlin Zhao, Ph.D., reported in an accompanying study (N. Engl. J. Med. 2012;366:2161-70).
Dr. Zhao, of the Chinese Center for Disease Control and Prevention, and colleagues reported on a national disease survey conducted in 2007. The survey showed that about 110,000 MDR cases were reported that year, and that 8,200 showed extensive drug resistance (XDR) – defined as resistance to isoniazid, rifampin, ofloxacin, and kanamycin.
China’s prevalence rate of multidrug resistance among new cases of tuberculosis was 3.5 times greater than the global median, and nearly twice the global average.
"With the use of the World Health Organization estimate of multidrug-resistant tuberculosis in various countries as a reference, China has the highest annual number of cases of MDR tuberculosis in the world – a quarter of the cases worldwide," the authors wrote.
A numbers of factors were linked to drug-resistant disease. Patients with multiple previous treatments – with the most recent taken in a tuberculosis hospital – were at the highest risk.
Poor compliance also influenced drug resistance. In a subanalysis of 226 patients who had received prior treatment, 44% had not completed their prior regimen. Among the 127 patients who had completed treatment, 115 had relapsed TB, and 62% had received that last treatment in the Chinese Center for Disease Control (CDC) system.
"This finding points to the need for interventions that will increase the continuity of treatment and reduce the rate of treatment default, especially among patients treated within the hospital system," the authors noted.
Because national facilities provide limited follow-up, the Chinese Ministry of Health has strengthened the hospitals’ follow-up capabilities, the investigators added.
More needs to be done, however, they noted. China’s CDC system, which is responsible for monitoring patients with tuberculosis in the community, could test new approaches to improving adherence to treatment, such as mobile-phone text messaging, and expand such approaches if they prove to be effective.
Improvements are imperative, the study authors cautioned, as the future does not bode well. About 11% of new cases and 16% of previously treated cases are already resistant to either isoniazid or rifampin, "placing them one step away from having MDR tuberculosis."
In addition, in patients with MDR but not XDR tuberculosis, more than one-third of cases were resistant to either ofloxacin or kanamycin – leaving those patients also just one step away from XDR tuberculosis.
Dr. Gler has received consulting fees from Otsuka Novel Products, the company that sponsored the trial. Neither Dr. Zhao nor any of the coauthors had any financial disclosures.