| Background:The rare diseases is defined as the number of patients accounting for the total population between 0.65‰ and 1‰ by World Health Organization, while some countries in the world have some differences in how to define the rare diseases. There is no official definition of the rare diseases of China, according to the definition of WHO, China has nearly ten million patients with rare diseases. China suffers from the absence of reliable epidemio logical data, so the prevalence of rare diseases has not been calculated. The lack of definition of rare diseases has become a problem to formulate the health policy of rare diseases. Epidemio logical studies have a profound meaning for rare diseases prevention and health promotion by studying the population distribution and the impact of disease and health factors.Aims:Through a retrospective study of rare diseases reported in China biomedical literature database between 1978 and 2013 to describe the distribution of rare diseases, and explore the research status of rare diseases. Finally it can provide the basic reference to research the cause of rare diseases. Combined with data reported in the literature, as well as the rare diseases’ data of inpatients in Shandong, Zhejiang, Anhui, Henan, Hebei and Jiangxi provinces, then we used DisMod-Ⅱ software to estimate the prevalence of rare diseases. Understanding the burden of disease and provide the basis for appropriate health policy.Methods:According to the directory of rare diseases published in orphanet web site, we entered the disease’s Chinese and English names and keywords, searched the rare disease reported in CBM database between 1978 and 2013. Then we extracted the reported time, the first author’s affiliation and the age, sex and other information of patients reported in 2011. Descriptive statistical analysis in the form of frequency distribution analysis was used and data were summarized to describe of distributions by time, place and hospital level reported in CBM database between 1978 and 2013 to find the characteristics of the epidemio logical distribution.According to the cases of hereditary spherocytosis reported in 2011 and combined with our sixth census data, we calculate the rough incidence of the disease; then we used DisMod-II software to estimate the prevalence. Compared with foreign literature’s results and the prevalence of EU to verify the validity of the estimated prevalence. According to the WHO global burden of disease model of the disease burden is calculated rare diseases. Then calculate the burden of disease by using the results.Results:According to 1,200 kinds of rare diseases in the EU rare diseases directory, there are 333 kinds of rare diseases reported in CBM database from 1978 to 2013, and a total of 108,335 cases. We performed a pooled analysis of disease cases and found that the number of cases not more than 100 cases accounted for 72.38%, while the number of cases only 1 cases accounted for 29 kinds; at the same time, the number of cases more than 1,000 cases only accounted for 6.3% and only 1 kinds of disease are greater than 10,000. The amount of detected rare disease showed an increasing trend as time increases. In spatial distribution,59% of reported cases occur in Shandong, Liaoning, Shanghai, Guangdong, Guangxi and Beijing. Tibet, Qinghai and Guizhou found reported cases account for less than 1%. In the grade of distribution hospital, 89% of rare diseases are reported by the third class-A hospitals, medical colleges affiliated hospitals and medical research institutes, and medical colleges affiliated hospitals accounted for 48%; only 11% of the cases reported by following the third class-A hospitals, and county hospitals and township hospitals are rarely.In the basis of the case of rare disease reported in the literature and the number of hospital inpatients, combined with the CDC of USA published the mortality of rare disease and estimated the remission, then through the DisMod-II software to calculate the prevalence of rare diseases. According to the literature data to estimate the prevalence of the total hemolytic anemia disease, other hemolytic anemia removed the thalassemia, thalassemia, paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis. The prevalence are 134.257,3.727,130.185,0.614,1.655 and 1.373 in 10 million people respectively. According to the data from hospitalized patients, the prevalence of paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis are 1.419,0.937 and 1.731 in 10 million people respectively. According to the reported cases of paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis, we estimated the patients of 333 kinds rare diseases were about 462,276 cases. Through the global burden of disease to calculate the burden of hereditary spherocytosis in 2011, the result is 0.0198 DALYs in one thousand people, the burden of disease constitution based on YLDs.Conclusions:According to the EU rare diseases directory, we retrieved 333 kinds of rare diseases reported in CBM database from 1978 to 2013, and atotal of 108,335 cases. This 1200 kinds of diseases are from "diseases and related health problems, the International Statistical Classification", which contain 2 class that are D (blood and blood-forming organs and certain disorders involving the immune disease mechanisms) and E (endocrine, nutritional and metabolic diseases). They have 984 kinds of rare diseases, and 312 kinds have been reported. Although the literature retrieval time range up to 36 years, but according to statistics there are case reports of 333 kinds of rare diseases.29 kinds of diseases had only one case reported, 48.65% was not higher than 20 cases,72.38% was not higher than 100 cases, only one kind was more than 10,000 cases. The largest number of cases reported in the literature are:congenital adrenal (cortex) hyperplasia, thrombotic thrombocytopenic purpura, Cushing’s disease, central diabetes insipidus, idiopathic central precocious puberty, central precocious puberty, idiopathic short stature, paroxysmal nocturnal hemoglobinuria, hyperphenylalaninemia and autoimmune hemolytic anemia.In the time,333 kinds of rare diseases reported in the CBM database from 1978 to 2013, the number of cases reported in the literature showing increasing in recent years. This is closely related to the continuing development of China’s economy, the raising of medical level and the wide concerning by community. In the space, according to the statistics of the 100 kinds of rare diseases that the largest number of cases reported in five provinces are Liaoning, Shanghai, Guangdong, Guangxi and Beijing. Which are in the east coast. According to "China Health Statistics Yearbook", that although the total number of hospital are closely in the Midwest and the eastern part, but the high-level hospital in the west is far less than the east. Unbalanced economic development in eastern and western regions, severe uneven distribution of medical institutions, as well as the difficulties of these underdeveloped areas may lead to rare disease is difficult to detect, while in fact there may be more patients. In the grade distribution hospital, the number of cases reported in the literature from three-level general hospitals, medical colleges affiliated hospitals and medical research institutes accounts for 89%, only 11% is from county hospitals and township hospitals. According to "China Health Statistics Yearbook", by the end of 2012, China had 23,710 hospitals, of which only 989 three-level general hospitals. 90% hospital are the following three-level, but occupying a large part of our health care resources, and the level of medical diagnosis rare diseases is far from enough. Due to the characteristics of rare disease diagnosis difficult, genetic testing agencies are very few rare diseases, only in Beijing, Shanghai, Guangzhou and several other important cities. So the state should pay attention to health care reform and rare diseases, provide more convenient medical services as well as develop appropriate health policies for patients.In the basis of the case of rare disease reported in the literature and the number of hospital inpatients, combined with the CDC of USA published the mortality of rare disease and estimated the remission, then through the DisMod-II software to calculate the prevalence of rare diseases. According to the literature data to estimate the prevalence of the total hemolytic anemia disease, other hemolytic anemia removed the thalassemia, thalassemia, paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis. The prevalence are 134.257,3.727,130.185,0.614,1.655 and 1.373 in 10 million people respectively. According to the data from hospitalized patients, the prevalence of paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis are 1.419,0.937 and 1.731 in 10 million people respectively. According to the reported cases of paroxysmal nocturnal hemoglobinuria, hemolytic uremic syndrome and hereditary spherocytosis, we estimated the patients of 333 kinds rare diseases were about 462,276 cases. Through the global burden of disease, we calculated the burden of hereditary spherocytosis in 2011 is 0.0198 DALYs in one thousand people, the burden of disease constitution based on YLDs. This situation explained that years lost due to disability is larger than years of life lost, the burden of disease is more serious caused by disability.In summary, under the condition of lack of basic data of rare diseases in China, we can use the rare disease cases reported in the literature to estimate the prevalence of rare diseases in China through the review of literature researched. This method is feasible and the result is credible. At the same time, it has an important significance for understanding the research status of rare disease in china. |
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