Распространенность туберкулеза в Китае снизилась вдвое за 20 лет
Thanks to a large-scale control program, China has more than halved its prevalence of tuberculosis over the past 20 years. A new analysis in the The Lancet examines how this has been achieved.
China began to address its growing tuberculosis (TB) problem in the 1990s when an "internationally recommended directly observed, short course strategy" (or DOTS) was implemented across half of the population.
Between 1990 and 2000, there was a 30% reduction in TB across the provinces that implemented the strategy. But the national prevalence fell by less than 20%. This is probably because only 30% of the estimated new TB cases were treated by the project.
The State Council of China attempted to boost TB control in 2001 with a new 10-year plan that had the goal of expanding DOTS to the entire nation.
By 2005, China had achieved the global TB control targets of detecting at least 70% of all TB cases and successfully treating more than 85% of these. China has been the only country with a high TB burden to meet the global control targets.
To examine how this was possible, the analysis published in The Lancet compared data from a 2010 survey - which screened 252,940 randomly selected people from all 31 mainland provinces of China for TB - with similar surveys conducted in 1990 and 2000. The people in the 2010 survey had chest radiographs taken, and all participants were interviewed by staff trained to diagnose TB.
China halves prevalence 5 years ahead of target
The study confirmed that between 1990 and 2010, the prevalence of smear-positive TB had fallen by 65% and the prevalence of bacteriologically positive TB had fallen by 48%. Consequently, China had achieved a crucial aim of the Stop TB Partnership, to reduce the prevalence of smear-positive TB by 50%. But China achieved this 5 years before the target date of 2015.
China's acceleration of the DOTS program in 2001 boosted the TB detection rate to nearly 80%, which in turn tripled the reduction rate in the 2000s, compared with the previous decade.
The two major changes influencing the improved performance of the control strategy were the DOTS program - which provided standard short-course chemotherapy - being expanded nationwide, and secondly, free treatment being offered to all TB patients, rather than just smear-positive cases.
However, 87% of the total decrease in prevalence was among cases already diagnosed with TB before the survey.
"The DOTS program has been much more effective in reducing the prevalence of tuberculosis in known cases than in new cases," say the authors.
"Because the prevalence in known cases is already very low, future reduction in tuberculosis prevalence is likely to slow substantially unless control efforts in addition to the DOTS strategy are implemented, especially in earlier case detection and treatment and use of new instruments."
Examining how China, a country that has previously had a large TB problem, has managed to exceed its control targets is important because a new agenda for global TB control is required after the current goals expire in 2015.
It is expected that the World Health Assembly will suggest a target of 50% reduction of TB prevalence between 2015 and 2025, which would represent an important milestone in global TB elimination.
The authors of this new analysis think their results show that such a target is feasible. They say:
"Countries can achieve this improvement with an aggressive scale-up of the DOTS program if they have not done so already, but improvement of the treatment of patients diagnosed outside the DOTS program, which is usually implemented only in the public sector, is essential."