This study showed that the months of higher active PTB registration rates in Henan Province were March, April, May, June. The ES model indicated that there were significant seasonal variations. The similar results were found at the national level and in other provinces. A study showed that from 2004 to 2008, April was the peak month for student TB cases in China, followed by May and March. March to June is the period of physical examination for students in the middle school entrance examination and the college entrance examination, which means a screening for students. This factor may be one of the reasons for the high registration rates from March to June. The seasonality of active TB registration was peaked in March in Xinjiang, China. There were also some studies on the seasonality and trend analysis of TB incidence around the world[21-24]. From 1993 to 2008, 21.4% cases were diagnosed in March, the peak month in the US.
A study in Singapore believed that the ARIMA model was effective in predicting the short-term trend of TB. Zhang et al.used seasonal ES model to predict the number of PTB cases in Shenzhen, in which the smooth R square was 0.68 and the Ljung-Box Q statistic P value was 0.86. Its parameters were close to that of the ES model in this study. The ES model is a time series analysis method developed on the basis of the moving average model. The ES value of any period is the weighted average of the actual observed value in the current period and the previous value. The ES model does not abandon the previous data, but gradually reduces the weight of the previous data.
Ríos et al. from Spain thought that the tubercle bacilli expelled from infected persons in a room with closed windows may increase the risk of exposure of healthy persons in winter and the clinical onset would be in spring. According to this, we thought that the seasonal peak in March in Henan Province may be related to the Spring Festival holiday. During the Spring Festival, all the family members gather together from everywhere to celebrate and seeing a doctor when feeling ill is a taboo. The closed windows in winter, large-scale mobilization, and health-seeking delay would jointly result in the increase and accumulation of PTB cases after the Spring Festival holiday, often in March. On World TB Day every year, many activities were organized in Henan to promote tuberculosis knowledge. This raises public awareness of TB, leading to seeking medical advice. This is one reason why the registration rates increased after March.
Globally, the average decline rate of the TB incidence was 1.6% per year during 2000 to 2018. From annual TB reports of the WHO, we can get Chinese annual TB registration rates from 2007 to 2018. The annual decline rate was 2.29% in China. From 2007 to 2019, the active PTB registration rate decreased from 88.0/100 000 to 49.0/100 000 with a 4.8% annual decline in Henan Province. Overall, the decline of incidence rate in Henan Province is greater than that in nationwide and worldwide. Du et al. thought that the decline of TB incidence and prevalence was related to economic development in China. Apart from economic development, we thought that it was related to the application of molecular biological diagnosis in Henan Province in recent years, so that patients can be diagnosed and treated in time
The hypothesis of time series analysis is based on the principle of inertia, that is, under certain conditions, the past trend of the predicted things will continue to the future. The ES model gives larger weight to recent observation values and gives smaller weight to earlier ones. In accordance with the decline trend in recent years, without the adoption of new measures, the predicted active PTB registration rate will reach 49.1 (95% CI: 36.2-62.0) per 100,000 population in 2020 and 34.4 (95% CI: 18.6-50.2) per 100,000 population in 2025 in Henan Province. Compared with the active PTB registration rate in 2015 (64.3/100,000), the reduction will be 23.7% (95% CI: 3.2%-44.1%) and 46.8% (95% CI: 21.4%-72.1%) in 2020 and 2025, respectively.
The missing report rate of infectious disease in medical institutions was 3.18% in 2012 in Henan province, top two were syphilis and TB. Assuming that the missing report rate of active PTB unchanged and keeping the TB control strategy remain unchanged in 2020 in Henan Province, without regard to the confidence interval, the first milestone (20% reduction) of WHO End TB Strategy in 2020 will be achieved.
The point prediction in 2025 was 34.4 per 100,000 population and it had a large range from 18.6 to 50.2 per 100,000 population. So, to achieve the second WHO milestone, new measures must be taken. In order to improve the diagnosis[32-35], treatment[36,37] and TB prevention services[38-40], a lot of research have been carried out around the world. A study from Nepal found that active case finding could reduce catastrophic costs. And the WHO milestones can only be achieved within the context of progress towards universal health coverage (UHC). In 2018, the policy of PTB diagnosis related groups based payment (DRGs) was launched in Henan Province. Patients only need to bear 20% of the fixed cost based on different clinical pathway. This financing policy will help to improve patient's treatment compliance. The End TB Strategy encompasses a package of interventions that fall under three pillars. Since 2020, the establishment of an electronic information system for hospitals, Centers for Disease Control and Prevention and primary health institutions will be explored to close gaps between incidence and notification in Henan Province. We will try to establish an infection control model based on primary health institutions to reduce the chance of infection in close contacts as well. We will carry out active screening of key populations and get multi-drug resistant TB (MDR-TB) patients timely diagnosed and treated . In 2015, the public total awareness rate of TB core information in Henan Province was 72.1%, so we need to strengthen public health education. We hope that with our efforts, the second WHO milestone objective will be achieved in 2025 in Henan Province.