Wednesday, January 14, 2009

Abdominal Height Predicts Risk from Obesity related diseases

There's good news for busy practitioners -- you can throw away those time-consuming BMI calculators and inconvenient tape measures -- we have a better way of estimating cardiovascular disease (CVD) risk: the simple ruler!

Yes, abdominal height (AH) measured as the distance from the exam table to the top of the belly when the patient is lying supine, has been shown in many studies to be a better predictor of cardiovascular disease than any other anthropometric measurement including BMI [body mass index], waist circumference, waist-hip ratio (WHR), and skin-fold thickness.[1-6]

Abdominal height also better correlates with an adverse metabolic profile including low HDL[high-density lipoprotein] and increased triglycerides, blood pressure, inflammatory cytokines, renal sodium reabsorption, blood glucose, and insulin resistance.[7-10] Abdominal height has also been associated with impotence, liver function abnormalities, and impaired pulmonary function.[11-14]

Abdominal height predicts cardiovascular disease risk because it is an excellent measure of visceral adiposity or intra-abdominal fat, which is associated with insulin resistance. Other anthropometric measurements are less specific for visceral adiposity since they include subcutaneous fat. Visceral fat drains through the portal circulation and bathes the liver with high levels of free fatty acids. These fatty acids can accumulate in the liver, leading to a fatty liver and abnormalities in insulin action and lipid synthesis.

Why hasn't the measurement of abdominal height caught on in the mainstream clinical practice? It is fast, simple, reliable[15] and a better predictor of cardiovascular disease than either BMI or waist-hip ratio. One major obstacle is the lack of reference ranges and cutpoints to assign risk categories. Another may be the embarrassment of telling a patient their beer belly is too big.
So remember, when your patient's belly enters your office before they do, think about getting out that ruler and measuring abdominal height. Unfortunately, for many of my patients that ruler will have to be a yardstick.

That's my opinion. I'm Dr George Griffing, Professor of Medicine at St Louis University and Editor in Chief for Internal Medicine of eMedicine.