The incidence rate for nonalcoholic fatty liver disease in the different ethnic population at high altitude

Objective To investigate the prevalence rate of nonalcoholic fatty liver disease (NAFLD) in the population undergoing physical examination at high altitude (above 2 000 m) and related risk factors.

Methods Physical examination was performed for 8888 individuals who lived at high altitude (above 2 000 m) in Qinghai province of China, and incidence and constitute of NAFLD were compared by ethnicity and elevation gradient.

Results The overall incidence rate of NAFLD was 39.09% in the areas above 2 000 m. There were significant differences in the incidence of NAFLD among ethnic groups(χ²=191.49, P<0.01). The incidence of NAFLD of Tibetan was significantly higher (χ²=181.81, P<0.01) and Hui (χ²=17.54, P=<0.01). The incidence of NAFLD increased with age (χ²=69.55, P<0.01). The incidence of Tibetan NAFLD has increased with elevation(χ²=31.89, P<0.01). The incidence of NAFLD in Han nationality increased with elevation (χ²=103.53, P<0.01). As altitude rises, the proportion of mild NAFLD were decreased(χ²=113.98, P<0.01), the NAFLD constitutes of the three groups was significantly different (χ²=132.95, P<0.01).

Conclusion There is a relatively high prevalence rate of NAFLD at high altitude, and there is a unique performance on the incidence and constitute of NAFLD among different ethnicity and among different elevation gradient.