Background
According to the WHO, the prevalence of periodontal diseases (PD), which includes gingivitis, gum bleeding, calculus, and periodontitis remains high in developing countries [
1]. Perhaps of 10 to 15% of adult are afflicted by PD, with an increasing prevalence with age [
2]. PD contributes to diabetes mellitus, cardiovascular disease and other systemic disorders and vice versa [
3]. This association likely exists because of common risk factors like tobacco use, poor diet, excessive alcohol consumption, stress, and unhygienic practices such as poor teeth brushing [
4]. Chronic PD was shown to adversely affect the quality of life of people with type 2 diabetes living in China by impacting chewing, socialization and speech [
5].
China’s third national epidemiological investigation on oral diseases (2005) revealed that periodontitis affected >50% of the adult population. Gingival bleeding and calculus occured in most 12-year-old (57.7, 59.1%), middle-aged adults(77.3, 97.3%) and elderly (68.0, 88.7%). In aging populations, 70–90% of individuals persons 60 and 74 suffered from PD [
6]. Drury et al reported there was a 10 to 20% difference in periodontal disease prevalence and severity between people of higher and lower socioeconomic status in the U.S. population [
7].
The Global Burden of Disease Study 2013 (GBD2013) have been used to estimate DALYs for 301 acute and chronic diseases and injuries in 188 countries for 1990–2013 [
8]. DALYs provide an overall estimate of the health of a population that accounts for years spent in ill health or disability. The general approach for the definition of PD of GBD 2013 was similar to that for GBD 2010. The GBD 2010 definition of severe periodontitis were based on “a Community Periodontal Index score of 4, a clinical attachment loss more than 6 mm or a gingival pocket depth more than 5 mm”, depending on which was used in the publication [
9]. Kassebaum et al [
10] provided the process including search strategy for identification of studies, selection of studies and data extraction and cleaning, data handling and modeling for estimation of prevalence and incidence for severe periodontitis in GBD 2010. Also, GBD 2010 data have used to estimate the PD burden in Global and Iran [
9‐
11].
The aim of our study is to describe DALYs in China for PD by province, sex, and age groups. To our knowledge, this is first study to estimate the burden of PD in China using GBD2013 data. The estimation of this study will provide a unique perspective for planning interventions and developing public health policies for PD even chronic diseases in China.
Discussion
PD SDR and the % PD SDR in all disease DALYs increased over 23 years. In nation-wide and all age population, compared to that of 1990, the SDR in 2013 increased slightly from 24.7 to 25.7. DALYs contributed by the % PD SDR for China was 0.06% in1990 and 0.11% in 2013. The west part of China had significantly higher variance ratio of PD SDR and % PD SDR in all diseases DALYs between 1990 and 2013 than those of other China parts. China’s DALYs estimation was much lower than that of global and Iran previously reported in 2010. Marcenes et al reported on the global DALYs of severe periodontitis was 97 and 108 in 1990 and 2010, respectively. DALYs in Iran did not noticeable change for periodontal diseases from 68.6 to 67.6 in 1990 and 2010. But the periodontal disease contributed to 0.8% of the total DALYs in 1990 and 2010 in Iran, which is less change than that of China.
The special outline of DALYs estimation in China have its specific explanation with the transition pattern of diseases occurrence among Chinese people during the period of more than 30 years. Firstly, China has undergone a rapid demographic and epidemiological transition during these times. Oral health is becoming a major public health problem as the prevalence of non-communicable diseases has greatly increased. According to a 2010 surveillance report, the estimated prevalence of diabetes among Chinese adults was 11.6% [
17]. During these 30 years, China has been conducted four national oral health epidemiology investigations. The 1995 and 2005 surveys indicated that the oral health status of the Chinese population has not improved with an increasing number of dentists and oral health institutions [
18]. Meanwhile, the number of retained teeth among urban adults aged 65–74 years increased from 18.80 to 21.98. These conditions resulted in a increased burden of periodontal diseases.
Secondly, China’s tobacco consumption increased at an annual rate of 5.3% starting in 1996. This increase could explain the parallel increased prevalence of PD and its related PD SDR over the last 23 years. Finally, more Chinese are being diagnosed with PD in selected areas. An investigation of national oral health departments in the Center for Disease Control and Prevention system was conducted in more than 3,000 provinces, city and county CDC institutes in 2013 (unpublished data). The results showed that 18 provincial CDCs, located in middle and western China, were cooperating with local oral technical institutes such as dental hospitals. Thus, these areas had local oral health promotion programs including free oral examination, oral health behavior guidance and oral health knowledge education. These areas had greater awareness of oral health and greater access to care. More patients were diagnosed with oral disease as well. Thus, the higher variance ratio of PD SDR and % PD SDR in all diseases DALYs observed in this study in the west areas of China may be explained by the differences in knowledge and coverage of oral care.
From China’s estimation, in contrast to men, the PD SDR changed slightly for women from 20.3 to 21.7. The variance ratio % PD SDR in all diseases DALYs was noticeably higher for women compared to men (94.5% vs 60.6%). Based on the China Adult Tobacco Investigation Report (2015), 52.1% of men and 2.7% of women smoke [
19]. Studies showed that the PD standardized DALYs rate of GBD 2013 in China was worse for men compared to women [
20,
21]. Some investigators believed that the burden of PD was higher in China for men because more men smoke compared to women and that smoking was a risk factor for tooth loss [
22,
23]. However, the variance ratio of PD standardized DALYs rate and % PD SDR in all oral diseases DALYs in women were higher than that of men, which may reflect health and education disparities in women.
PD SDR among all 14 age groups in 2013 increased slightly more than that in 1990. The highest variance ratio of % PD SDR in all disease DALYs were in the age groups 20–29 years (50.5%), Compared to middle and older age adults, young Chinese adults had a lower social and economic status. We can inferred that 1) young adults with low income have financial barriers to accessing oral health care; 2) are less likely to be aware of the need for comprehensive, ongoing dental care, and 3) are more likely to use tobacco and have a poor lifestyle [
24]. Further, young adults with lower education may lack adequate oral health knowledge, not engage in preventive behaviors, and may under use oral health services [
25]. Sabbahet al argued that access to dental care is the main factor in socioeconomic disparities in oral health [
26]. So, much more young adults were diagnosed with PD.
This study has several limitations. First, our conclusions are limited by the quality of data inherent in GBD 2013 such as sampling and non-sampling error, model specification, and model parameter estimation [
27]. Further, describing DALYs for PD is less straight forward compared to other chronic diseases such as mental illness. Disability may be subtler, such as decline in nutrition over many years or overshadowed by a person’s other co-morbidities. Thus, DALYs may only be one of many tools to quantity a nation’s oral health. The incidence of PD should be integrated with the DALYs to accurately estimate the disease burden of PD. The fourth national oral health epidemiological investigation began at the end of 2015 and will conclude in 2017. The results will help to better determine the true burden of oral health diseases.
Acknowledgements
We wish to thank the epidemiologist of National Center for Chronic and Non--Communicable Disease Control and Prevention, who assisted with GBD explanation and draft the analysis plan of this study collection.