Tuesday, October 27, 2009

Small thigh circumference and cardiac risk

Here's a new take on body build and health! We are all familiar with the apple/pear thing in that those who carry their weight around the waist in an apple-ish silhouette are at greater risk of heart disease than those whose excess pounds hang on their hips. These Danish researchers took the measurements one level lower(1); here's what they found:

Professor Berit Heitmann and company from Copenhagen's Research Unit for Dietary Studies took tape measure to thigh on over 2800 legs still attached to as many Danes, then followed the group for 12+ years checking out incidence of heart disease and death. Pipe cleaner thighs that fell short of 60 cm. (23.6 in.) in circumference were an independent risk marker for both unfortunate endpoints.

So what's the problem with skinny thighs? Two of our biggest muscles are contained therein, namely the quadriceps and the hamstrings. A loss of muscle mass could be a marker for inactivity or chronic disease such as COPD that prevents exercise. In fact, a Canadian study found that loss of mid-thigh muscle mass as measured by CT scanning was a better predictor of mortality in chronic pulmonary patients than a low body mass (both indicative of the wasting associated with lung disease).(2) Less muscle mass is also known to predispose to insulin resistance and type 2 diabetes as demonstrated by the elevated fasting blood sugars and cases of diabetes that we unexpectedly see in scrawny old ladies.

So should we be measuring thighs along with waistlines, blood pressures, and pulse rates (and also asking about physical activity, sleep habits, diet histories and domestic violence in the leftover minutes of annual physicals)? Says Australian epidemiologist Dr. Ian Scott in an editorial accompanying the Danish study: "Will this association help clinicians predict risk in individual patients more accurately than they already do using readily accessible and validated risk calculators? The answer is — we do not know."

I, for one, shall pass for now.
(1) Heitmann, BL et al. Thigh circumference and risk of heart disease and premature death: prospective cohort study. BMJ. 2009 Sep 3;339:b3292. doi: 10.1136/bmj.b3292.
(2) Marquis, K et al. Midthigh muscle cross-sectional area is a better predictor of mortality than body mass index in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2002 Sep 15;166(6):809-13.


Anne Morley said...

If you have a scrawny old lady or a chronic Copd person they are probably pretty entrenched in their lack of activity. You already screen for diabetes, you already know the muscles are wasting. Can you realistically motivate them to exercise and build muscle? Use that extra minute in the exam to connect with the person instead of measuring their thigh.

dorsey said...

finally! no scrawny thighs here. I think you can probably eyeball it anyway, or ask the person to pick up something heavy and see if they use their hamstrings. Or if they have a heart attack trying. I do have the ear crease that's supposed to be a predictor, any idea what that correlates to?