Diagnostic performance of body mass index to detect obesity in patients with coronary artery disease.
BACKGROUND
Emerging evidence suggests that a mildly elevated body mass index (BMI), is related to improved survival and fewer cardiovascular events in patients with coronary artery disease (CAD). We hypothesize that these results are related to the poor diagnostic performance of BMI to detect adiposity, especially in the intermediate BMI ranges.


RESULTS
A cross-sectional study of 95 patients with CAD referred to phase II cardiac rehabilitation. Body fat (BF)% was estimated by air displacement plethysmography. Height, weight, BMI and waist circumference were measured the same day. We calculated the correlation between BMI and both, BF% and lean mass and assessed the diagnostic performance of BMI to detect obesity defined as a BF% > 25% in men and > 35% in women. Although BMI had a good correlation with BF% (rho = 0.66, P < 0.0001), it also had a good correlation with lean mass (rho = 0.41, P < 0.0001), and BMI failed to discriminate between both (P-value = 0.72). A BMI >or= 30 kg/m2 had a good specificity (95%; 95% CI, 83-100) but a poor sensitivity (43%; 95% CI, 32-54) while a BMI >or= 25 kg/m2 had a good sensitivity (91%; 95% CI, 84-97) but a poor specificity (65%; 95% CI, 42-88) to detect BF%-obesity.


CONCLUSIONS
In patients with CAD, BMI does not discriminate between BF% and lean mass, and a BMI < 30 kg/m(2) is a poor index to diagnose obesity. These findings may explain the controversial findings that link mild elevations of BMI to better survival and fewer cardiovascular events in patients with CAD. Body composition techniques to accurately diagnose obesity in patients with CAD might be necessary.
Romero-Corral
Abel
A
Division of Cardiovascular Diseases, Department of Internal Medicine, Gonda 5-368, 200 First Street SW, Rochester, MN 55905, USA.
Somers
Virend K
VK
Sierra-Johnson
Justo
J
Jensen
Michael D
MD
Thomas
Randal J
RJ
Squires
Ray W
RW
Allison
Thomas G
TG
Korinek
Josef
J
Lopez-Jimenez
Francisco
F
D000273:Adipose Tissue / Q000473:pathology; D050154:Adiposity / Q000502:physiology; D015992:Body Mass Index; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000150:complications* / Q000473:pathology / Q000534:rehabilitation; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000175:diagnosis*; D015588:Observer Variation; D018570:Risk Assessment; D049629:Waist-Hip Ratio