Normal BMI in NAFLD patients is associated with a higher risk of cardiovascular disease

A retrospective cohort study including more than 10,000 adults with non-alcoholic fatty liver disease (NAFLD) showed that, surprisingly, lean people with NAFLD have a higher risk of cardiovascular disease than those who are overweight or obese. This held true despite lean patients having a lower prevalence of risk factors like hypertension and dyslipidaemia.

“It seems counterintuitive that those with a normal BMI would have a higher prevalence of cardiovascular disease (CVD), but our research highlighted this connection,” said lead study author Dr Karn Wijarnpreecha (University of Michigan, MI, USA). “This finding could have significant implications on patient care and warrants further analysis.” Although most NAFLD patients are overweight or obese, approximately 10–20% have a normal BMI.

The retrospective cohort study looked at 18,793 adults with NAFLD at the University of Michigan from 2012 to 2021. Patients were categorised into lean (BMI 18.5–24.9), overweight (BMI 25–29.9), class 1 obesity (BMI 30–34.9), or class 2–3 obesity (BMI 35–<40). Prevalence of cirrhosis, CVD (coronary artery disease, congestive heart failure, cerebrovascular diseases, and peripheral arterial diseases), metabolic diseases (diabetes, hypertension, dyslipidaemia), and chronic kidney disease were assessed in the various groups.

The results showed that, compared with NAFLD patients who were overweight or obese, lean NAFLD patients had a significantly higher rate of CVD even though they had a significantly lower prevalence of risk factors associated with CVD, such as diabetes, hypertension, and dyslipidaemia. “A logistic regression analysis of the association between BMI categories and prevalence of CVD controlled for confounders showed a significantly lower prevalence of coronary artery disease and cerebrovascular disease in overweight and obese subjects,” Dr Wijarnpreecha said during the presentation. Compared with lean NAFLD patients, overweight patients had an odds ratio (OD) of 0.8 and obese patients (both class 1 and class 2–3) an OR of 0.7.

Almost 6% of lean patients had peripheral arterial disease, compared with rates of approximately 4%–5% in overweight people and people with obesity. Similarly, more than 6% of the lean group experienced a stroke, compared with 5% or less of the other BMI groups. However, lean patients had a lower prevalence of cirrhosis, diabetes mellitus, hypertension, dyslipidaemia, and chronic kidney disease.

A limitation of the study is its retrospective design. “We cannot definitively state that lean NAFLD patients have a higher risk of CVD. The only conclusion we can draw from this study is that there was a higher prevalence of CVD in the lean group than in the overweight or obese NAFLD groups. Whether lean NAFLD patients are going to develop CVD or have a higher risk requires additional research,” said Dr Wijarnpreecha. Future prospective studies should further explore the risk and incidence of comorbid conditions in NAFLD patients and how it relates to BMI.

Due to these results, Dr Wijarnpreecha recommended that “NAFLD patients with a normal BMI should not be overlooked in clinical practice.”

1. Wijarnpreecha K, et al. Higher prevalence of cardiovascular disease among lean versus non-lean patients with nonalcoholic fatty liver disease despite lower prevalence of atherogenic risk and metabolic diseases. Lecture 325, Digestive Disease Week 2022, 21–24 May, San Diego, CA, USA.

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Posted on 14 June 2022