What are the estimated numbers of cases ofNAFLD and NASH?
As could be expected, primary NAFLD isobserved principally in developed countries. In these societies, a sedentarylifestyle and high calorie, sugar, and fat diets lead to DM2 and obesity.
Thus, in developed countries, the overallprevalence of NAFLD in the population is estimated to be approximately 20%, andthat of NASH 3%. The prevalence of each is presumably much higher in obese anddiabetic persons. The reason for this presumption is that upwards of 55% ofpatients with NASH have DM2 and 95% are obese. Thus, the prevalence of simplefatty liver in obese persons can be estimated to be approximately 90% and thatof NASH in obese persons to be 20%. NASH is typically a disease of middle-agedoverweight women with predominantly central (abdominal) fat distribution.However, there are also increasing reports of NASH related to obesity in menand even in pediatric populations.四川省第四人民医院消化内科常玉英
The Center for Disease Control reports thatcurrently, approximately one half of the USadultpopulationisoverweight (BMI>25) and one quarter of the US adultpopulationisobese(BMI>30). Projecting the prevalence of NAFLD and NASH inthe obese subpopulation to the entire population would suggest that upwards of29 million Americans have NAFLD and 6.4 million of these persons have NASH.
These estimates, however, are very general.Another way to guesstimate is to study the relationship between the BMI andelevated liver enzymes (serum transaminases). You see, elevated transaminasescan be caused by NAFLD in obese individuals. Thus, as compared to a normal BMIof less than or equal to 25, the risk of having elevated transaminases for menis roughly 2 times greater for a BMI of 25-30, 4 times greater for a BMI of30-35, 5 times greater for a BMI of 35-40, and 6 times greater for a BMIgreater than 40. For women, the risk is 2 times greater for a BMI of 25-30, 2.5times greater for a BMI of 30-35, 4 times greater for a BMI of 35-40, and 5times greater for a BMI greater than 40.
The bottom line is that currently, NAFLD isthe most prevalent liver disease in the Unites States, representing anestimated 24% of cases of liver disease.