The Relationship Between Waist Circumference, Liver Disease

In this video, Naim Alkhouri, MD, speaks about the relationship between waist circumference and NAFLD/ NASH, including the risk for NAFLD and fibrosis in people with HIV compared with the general population, the relationship between visceral fat and the liver, and why clinicians should use waist circumference to identify their patients most at risk for NAFLD and metabolic disease.

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Naim Alkhouri, MD, is the Chief Medical Officer and Director of the Fatty Liver Program at Arizona Liver Health (Phoenix, Tucson, AZ).

TRANSCRIPTION:

Naim Alkhouri, MD: Hi, this is Dr Naim Alkhouri. I'm the Chief Medical Officer and the Director of the Fatty Liver Program at Arizona Liver Health in Phoenix and Tucson, Arizona.

Consultant360: What is the risk for NAFLD and fibrosis in people with HIV compared with the general population?
Dr Alkhouri: Non-alcoholic fatty liver disease, or NAFLD, affects about 25% of the general adult population in the United States. But unfortunately, patients or people living with HIV have a higher risk. Previous studies showed that approximately 35% of patients with HIV may have evidence of NAFLD, and they tend to progress faster in terms of fibrosis stages, and that can lead to complications, including the development of cirrhosis, and potentially liver cancer. So, patients with HIV have a higher risk of developing fatty liver disease and progressing to more advanced forms of fatty liver.

C360: What is the relationship between visceral fat and the liver?
Dr Alkhouri:  When we think about different types of fat, we think about visceral fat, or visceral adipose tissue vs subcutaneous adipose tissue, and visceral adipose tissue is more metabolically active, and it can cause actually more fat deposition and to deliver through the release of fatty acids through the portal circulation, and these free fatty acids can deposit in the liver cells and lead to the formation of triglycerides and lipid droplets. And this is really the beginning of non-alcoholic fatty liver disease that can lead to further liver inflammation, liver cell injury, and eventually the development of liver fibrosis.

C360: How much weight should a patient lose to help with fatty liver disease? How do you recommend patients do that?
Dr Alkhouri:  Several studies showed that in patients living with HIV, having more visceral adiposity and higher waist circumference is actually predictive of the presence of fatty liver disease, and also more progression to significant liver fibrosis. So you can have two patients with the same weight and same BMI, body mass index, but one with visceral adiposity, the other one with less visceral adipose tissue, the patient with more visceral or central adiposity would be at higher risk for NAFLD and significant fibrosis.

C360: Given its relationship to visceral fat, how predictive is waist circumference for NAFLD and fibrosis?
Dr Alkhouri: So, in one study that followed patients over one year, there was progression by one fibrosis stage in 38%. In that study, they looked at factors that predicted fibrosis progression, and there was really no association between body mass index, not even the percentage of liver fat. The only predictor was actually the visceral adipose tissue area. So that implicates visceral adipose tissue and central adiposity with fibrosis progression in patients with HIV and NAFLD.

C360: How much weight should a patient lose to help with fatty liver disease? How do you recommend patients do that?
Dr Alkhouri: Weight loss is the mainstay of managing fatty liver disease. Any weight loss is good, so even losing as little as 3 to 5% may be associated with reduction in liver fat. But if we want to achieve what we call NASH resolution, which is really the resolution of liver cell injury and minimal inflammation, you need to lose about 7% of your total body weight. And then studies have shown that if you want to achieve fibrosis regression, that probably the goal should be around 10% of the total body weight. So, in my clinical practice, this is what I recommend for my patients, is to try to achieve that 10% total body weight loss. To simplify it, if the patient is at 200 pounds, we recommend a 20-pound weight loss, and we do this gradually over a period of six to 12 months, and this should be associated with improvement in NAFLD liver inflammation, and hopefully also liver fibrosis.

C360: How does waist circumference perform as a NAFLD risk factor specifically in people with HIV?
Dr Alkhouri: In a study that included over a thousand women mainly living with HIV, but also had some seronegative women, they did a FibroScan test and calculated a score called the FAST score. This includes three measurements: one is liver stiffness on FibroScan, the other one is the CAP score, which estimates liver fat, and the third one is a blood test called AST, that estimates liver inflammation. So in that study, we looked at the percentage of women with a FAST score more than 0.35, and found that this percentage was definitely higher in women with HIV compared to seronegative women. And then when we looked at the predictors, waist circumference was associated with higher chances of having a high FAST score. The FAST score indicates the presence of NASH and significant fibrosis, and per 10-centimeter increase in waist circumference, the chances of having a high FAST score increased by 65%, and this was statistically significant. It is important to highlight that in women with HIV, the prevalence of a high FAST score was at 6.3% compared to only 1.8% in seronegative women.

C360: What other health outcomes are associated with elevated waist circumference?
Dr Alkhouri: Elevated waist circumference is a predictor of poor metabolic health, so in addition to fatty liver disease, it has been associated with metabolic syndrome, type 2 diabetes, prediabetes, and dyslipidemia. And there's also a concept of what we call lean NAFLD or skinny NAFLD, so individuals that are considered lean based on their BMI, but then they have that central adiposity, and this is associated again with NAFLD and metabolic syndrome, and type 2 diabetes insulin resistance.

C360: Should clinicians use waist circumference to identify their patients most at risk for NAFLD and metabolic disease?
Dr Alkhouri: I think waist circumference should be measured routinely in clinics if time allows, and given the recent data on the prevalence of NAFLD in people living with HIV, my practice is to actually screen for NAFLD in all HIV-infected individuals. And if you have access to a FibroScan machine, this is a very cost-effective way to screen for NAFLD, where you actually determine the amount of fat and the presence of fibrosis. But if this is not available, there are simple scores that can be calculated in the clinic, including the FIB-4 Index, where you need just AST, ALT, platelet count, and age. And there are some also commercially available scores that can screen for the presence of fibrosis in patients with NAFLD. A simple liver ultrasound can show you also fatty liver.

So I think you need to utilize the tools available to you to screen for fatty liver disease in people living with HIV, and my approach has been to screen everyone. There is cost-effectiveness analyses today showing that it's cost-effective to screen patients with type 2 diabetes, for example, starting at the age of 45, and I think it is time to start considering doing a routine screening for NAFLD in all subjects living with HIV.

Dr Alkhouri: Thank you for watching this video. It's been a pleasure, and I hope the take-home message has been clear, that people living with HIV are at high risk for NAFLD and progression to more advanced fibrosis. So please think about it and screen where indicated, and utilize the tools available to you in your clinical practice. Thank you.