In this study, we have for the first time calculated the DALYs of Chinese sCJD based on 753 probable sCJD cases from 2013 to 2017. Overall, there are 16202.62 DALYs for 753 sCJD cases from 2013–2017, with the average annual loss of 3240.52 DALYs. Patients with the ages from 45 to 69 are most affected populations, contributing to 79.3% of the DALYs. Moreover, YLLs each surveillance year contribute over 95% of individual annual DALY, reflecting, from another point of view, a rapid progression and short duration of sCJD.
It is well known that if the clinical course of a disease is relatively stable, the results based on the numbers of disease using are close to that of the numbers of morbidity. In general, the exact data of morbidity are relatively difficult to obtain, while the data of the people with a special disease are much easy to be acquired. We have to confess that the numbers of sCJD in this study are far below the expected morbidity, which is hard to represent the accrual DALYs of sCJD in China. However, the morbidity of sCJD is fairly stable worldwide, which maintains 1 to 2 case /million /year (17). Although the calculated incidences of sCJD in some European countries show increasing trend during the past decade, the enhanced surveillance capacities are believed to be the reason (18, 19). In fact, based on our 10 years CJD surveillance data in Beijing, the incidence is close to 1 case/million/year(20). Taking this morbidity data and the population in China, the annual case numbers of sCJD in China should be 1400 to 2800. Subsequently, according to the DALYs of 753 sCJD cases in this study, the average annual DALY of sCJD is estimated as 30124.36 to 60248.71 person-years. With the average population for the five years from 2013 to 2017 as the denominator, the DALY intensity of sCJD in China would be predicted as 0.022 to 0.044 person-years per 1,000 population, or 2.2 to 4.4 person-years per 100,000 populations.
By reviewing the published data, we have compared the predicted DALY intensity of sCJD in China with other neurodegeneration diseases, malignant tumors and some infectious diseases in China (Table 3). As expected, AD and many malignant tumors, e.g., lung cancer, liver cancer, stomach carcinoma and pancreas cancer possess much high DALYs. The DALY of sCJD seems to be comparable with those of multiple sclerosis (3.32 person-years/100,000) and myasthenia gravis (2.23 person-years /100,000). Compared with infectious diseases, the DALY of sCJD is obviously lower than that of TB, AIDS, syphilis and hepatitis B, similar as rabbis, and higher than that of hepatitis C, measles and Shigella dysentery. It indicates that although the morbidity of sCJD is low, its 100% fatality cause relatively high DALY.
Table 3
Comparison of the DALY intensities of different diseases
Disease | DALY intensity (person-years /100,000) |
Alzheimer disease | 503 |
Lung cancer | 462 |
Liver cancer | 325 |
Stomach cancer | 96 |
Lung tuberculosis | 82.3 |
Pancreas carcinoma | 26.23 |
AIDS | 8.2 |
Syphilis | 7.7 |
Hepatitis B | 6.0 |
sCJD | 4.4–2.2 |
Multiple sclerosis | 3.32 |
myasthenia gravis | 2.23 |
Rabbis | 2.2 |
Hepatitis C | 0.3 |
Measles | 0.3 |
Shegella dysentery | 0.2 |
The total indirect economic burden of 753 sCJD patients from five years is estimated to be 372.08 million RMB. sCJD usually occurs in the older people. 475 of 753 sCJD patients (64.6%) in this study are over 60 year-old, but account for only 11.4% of indirect economic burdens. It is understandable since we have set in this study that the main labor force for society production is the population from 14 to 59 y. However, more and more senior persons over 60 years old continue to work in China, particularly in the central cities. In addition, the retirement age in China probably will be postponed from 60 to 65 year-old. Those factors will influence the estimation of indirect economic burdens of diseases, especially the diseases involving in elder population.