The impact of body mass index on clinicopathological features of nonalcoholic fatty liver disease in Taiwan

BACKGROUND AND AIM

The aim of this study was to assess the impact of body mass index (BMI) on the clinical and histological characteristics of patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

Patients with clinically diagnosed NAFLD who received liver biopsy were retrospectively enrolled from 2007 to 2019. For comparison, all of the patients were divided into lean body mass (< 23 kg/m² ), overweight (23-24.9 kg/m² ), and obesity (BMI ≧ 25 kg/m² ).

RESULTS

A total of 572 patients with histologically confirmed NAFLD, including 40 (6.99%) lean body mass, 54 (9.44%) overweight, and 478 (83.57%) obese patients, were recruited. Obese NAFLD patients had significantly higher grade of steatosis (grade 3: 29.92% vs 22.22% vs 12.5%, P < 0.0001) and hepatocyte ballooning (grade 2: 14.85% vs 12.96% vs 12.5%, P < 0.0001) than overweight and lean NAFLD patients. The prevalence of nonalcoholic steatohepatitis (NASH) was 22.5%, 25.93%, and 36.19% in lean, overweight, and obese NAFLD patients, respectively. Obesity was significantly associated with fibrosis severity (P = 0.03). The fibrosis index based on four factors (FIB-4) score can identify NAFLD patients without significant fibrosis or with cirrhosis. The areas under the receiver-operating characteristic curve of FIB-4 score to identify patients without significant fibrosis or with cirrhosis were 0.82 (95% confidence interval [CI]: 0.69-0.96) and 0.87 (95% CI: 0.76-0.99) in lean patients; 0.77 (95% CI: 0.61-0.93) and 0.81 (95% CI: 0.59-1.0) in overweight patients; and 0.77 (95% CI: 0.72-0.82) and 0.89 (95% CI: 0.85-0.92) in obese patients.

CONCLUSIONS

The majority of NAFLD patients are obese, as defined by BMI. Obesity was significantly associated with NASH and hepatic fibrosis severity in patients with NAFLD.