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

Abstract

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.

Keywords: body mass index; fibrosis; fibrosis index based on four factors (FIB-4) score; nonalcoholic fatty liver disease; nonalcoholic steatohepatitis.