Additionally, the transformed prevalence is weighted very slightly toward 50%, and studies with prevalence of zero can thus be included in the analysis.

The pooled proportion is calculated as the back-transform of the weighted mean of the transformed proportions, using inverse arcsine variance weights for the fixed effects model and DerSimonian-Laird weights for the random effects model: Two thousand one hundred forty-one studies were identified after an initial search. After removal of duplicates and initial screening, we reviewed 227 papers in full. After exclusion of ineligible reports, our final sample was 48 studies[14-61] published between January 1987 and June 25, 2013. The flow diagram of the search process is exhibited

in Figure 1. The characteristics of studies on the prevalence Selleckchem KPT330 of NAFLD were shown in the Table 1. The population size of the reviewed studies ranged from 805 to 95 567 with a median sample size of 3205 people. The studies included a total of 356 367 people. Forty-six reports reported data on men (n = 201 481) and 45 reports reported the data on women (n = 152 124), 6 included mixed gender samples (n = 2762). One investigated women (n = 8769) and one for men (n = 1043). In the surveys with samples, more than 60% of the individuals were men. The weighted average age of men (46 reports) and women (45 reports) was 40.32 and 34.8 years old, respectively. Selleckchem PLX-4720 Twenty-three reports were from the southern part of China (n = 242 107), 25 reports were from the northern part of China (n = 114 260), 24 reports were from facility (n = 159 353), 24 were from the general population (n = 197 014), 20 were from urban (n = 185 875), 3 was from rural (n = 8752), and 25 was from the mixed (n = 161 740). Table 1 show detailed information from the 48 studies selected. The point prevalence of NAFLD with the 48 individual study populations ranged between 6.19% and 38.24%, with an overall meta-analysis

prevalence of 20.09% (95% CI: 17.95–22.31%, Fig. 2) and evidence FAD of high-level heterogeneity between studies (I2 = 99.6%, P < 0.0001). Pooled prevalence of all subgroups according to sex, mean age, age group gender ration, study year, sample size, population source, location, and area are presented in Table 2. The summarized prevalence of male (24.81%, 95% CI: 21.88–27.87%, Fig. 3) was higher than that of female (13.16%, 95% CI: 11.33–15.11%, Fig. 4). The pooled prevalence estimate increased over time. Between the years 2000 and 2006, the pooled prevalence estimate was 18.22% (95% CI: 14.32–22.48%), which increased to 20.00% (95% CI: 16.84–23.36%) between 2007 and 2009; the estimate was 20.86% (95% CI: 15.41–22.72%) in the years 2010–2013. In two age groups (< 45 and ≥ 45 years old), the prevalence estimates in studies with people older than 45 years old were higher than estimates of people younger than 45 years old group (20.44%, 95% CI: 17.70–23.32%). The pooled prevalence estimate also increased over age.