Abstract
This study was aimed to devise a theoretical formula for the mid-age of incidence (MAI) from the prevalence of age groups and to confirm its application. The formula was devised using the concept of lost years of health and then simulated. In the inhabitants’ survey, MAI was calculated from the prevalence of liver disease in the areas, and the main cause of disease was analyzed between those areas where MAI was lower than 2.5% of the distribution with significantly high prevalence (HL group) and those areas where MAI was higher than 2.5% of the distribution with significantly high prevalence (HU group). In the computer simulation, MAI was not much different or a little lower than the mid-age of occurrence. In addition, the sum of the incidence rates in the 1-year age groups approximately corresponded to the maximum prevalence within the age groups in the simulation. In the HL group, the main cause of liver disease was alcoholic liver injury; in the HU group, one cause was type C hepatitis, whereas for many others, it was advanced alcoholic liver injury. Thus, the HU and t HL groups were confirmed as active and quiescent areas, respectively. Investigating the cause or stage is considered to be useful in future studies. Key words: Mid-age of incidence (MAI), Lost years of health, chronic disease, prevalence, age specific prevalence.
Highlights
Romeder and McWhinnie (1977) introduced the ageadjusted (AA) (Armitage et al, 2002) years of potential life lost (YPLL) rate as follows: when ni is the population of the ith age group in some area, di is the number of deaths in some area, Nir is the standard population andNr is the standard population between the age groups 1 and 70 years, This index is referred to as the health index, whichThis index is referred to as the health index, which denotes the years of potential health lost (YPHL) (Inoue, 2002)
The formula is given as follows: Where Pi is the prevalence in the ith age group, ci is the normalized weight for length of each age group, and adjustment is used for the equivalent average:
Pi is the prevalence in the ith age group, ci is the normalized weight for length of each age group, and age adjustment is used for the equivalent average; Reference age for calculation of mid-age of incidence (MAI)
Summary
Romeder and McWhinnie (1977) introduced the ageadjusted (AA) (Armitage et al, 2002) years of potential life lost (YPLL) rate as follows: when ni is the population of the ith age group in some area, di is the number of deaths in some area, Nir is the standard population andNr is the standard population between the age groups 1 and 70 years, This index is referred to as the health index, whichThis index is referred to as the health index, which denotes the years of potential health lost (YPHL) (Inoue, 2002). Romeder and McWhinnie (1977) introduced the ageadjusted (AA) (Armitage et al, 2002) years of potential life lost (YPLL) rate as follows: when ni is the population of the ith age group in some area, di is the number of deaths in some area, Nir is the standard population and. Nr is the standard population between the age groups 1 and 70 years, . This index is referred to as the health index, which. When di is the number of AA - YPLL rate (70 mid age of i th age group) i 1 License 4.0 International License patients in the ith age group, ni is the number of examinees, Pi=di/ni is the prevalence, and the reference age shows T(>74), the YPHL rate in the ith age group is (T-mid age of the ith age group) × di/ni.
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