Cumulative BMI Could Forecast NAFLD Risk

An increase in body mass index (BMI) over time could increase the risk of non-alcoholic fatty liver disease (NAFLD).

A team, led by Baoyu Feng, Department of Epidemiology and Biostatistics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences; School of Basic Medicine Peking Union Medical College, evaluated the link between cumulative BMI and long-term BMI change on patients with NAFLD.

In the study, the investigators examined 19,477 adult patients from the Kailuan study from 2006-2013. Of this patient population, the overwhelming majority (n = 12,556) were male.

Identifying BMI Over Time

The investigators assessed cumulative BMI using a quadratic mixed-effects method by sex prior to the index year. They then follow-up with patients for NAFLD until December 2019.

Finally, the team calculated the long-term BMI change as the percentage change in average cumulative BMI from the baseline BMI.

Overall, 6229 participants were diagnosed with NAFLD during a median follow-up of 5.63 years.

The Risk of NAFLD

The risk of developing NAFLD increased with cumulative BMI independent of baseline BMI (intermediate tertile: aHR, 1.60; 95% CI, 1.48-1.73; highest tertile: aHR, 2.28; 95% CI, 2.06-2.53; P <0.001).

This association was even more pronounced in women and younger participants.

The NAFLD risk increased in the baseline BMI < 24 kg/m2 group with weight gain (BMI change: > 3%) compared to a stable weight (BMI change: -3% to 3%). In addition, the risk decreased in the BMI ≥ 24 kg/m2 group with weight loss (BMI change: < -3%) for men and women.

However, the investigators only identified a decreased risk of NAFLD in men (HR, 0.82; 95% CI, 0.69-0.97) with BMI < 24 kg/m2 and weight loss.

“Monitoring cumulative BMI may help to identify high-risk NAFLD populations,” the authors wrote. “The association between weight gain or loss varies by sex and baseline BMI, suggesting the importance of individualized weight management for NAFLD prevention.”

Lean Vs. Obese Patients

Earlier this year, investigators identified many similarities between lean and overweight or obese individuals with NAFLD.

A team, led by Archana Rastogi, Institute of Liver & Biliary Sciences (ILBS), evaluated the prevalence of NAFLD in lean patients and explored clinico-pathological spectrum of lean NAFLD in comparison to over-weight or obese individuals.

The results show leaner patients had a significantly lower BMI and waist circumference, as well as lower fasting glucose levels in comparison with the overweight or obese groups. However, the remainder of metabolic parameters were virtually the same.

On the other hand, lean patients had higher serum ALT levels and histological characteristics, including ballooning of hepatocytes and steatosis than the other groups.

For lean patients with NASH-related cirrhosis, 20.9% had lobular inflammation and advanced fibrosis, which is significantly less common than the other groups of patients.

Further immunophenotypic studies showed the inter-relationship of HPCs, HSCs, and macrophages was influenced by the stage of fibrosis, but was not influenced by BMI.

The study, “Effect of cumulative body mass index exposure and long-term related change on incident non-alcoholic fatty liver disease,” was published online in Liver International.