Obesity as an independent influential factor for reduced radial arterial wave reflection in a middle-aged Japanese male population.

This study aimed to examine whether obesity, including abdominal obesity, is an influential factor for radial arterial wave reflection, as expressed by the augmentation index (AI), in middle-aged Japanese men. Radial arterial pressure waveform was measured using automated applanation tonometry in 828 men (mean age: 47+/-5 years) during an annual health examination at a company. Radial AI was calculated from the waveforms. AI appeared to be similar between subjects with and without obesity (body mass index (BMI) >or=25 and <25 kg m(-2), respectively). However, after adjusting for age, height, heart rate, mean blood pressure, low- and high-density lipoprotein cholesterol, fasting plasma glucose, white blood cell count and other potential confounders, AI was significantly lower in subjects with obesity (71.6%, 95% confidence interval (CI); 70.2-73.0%) than in those without (75.2%, 95% CI; 74.4-76.0%, P<0.001). In a multiple linear regression analysis, BMI was negatively associated with AI (beta=-0.20, P<0.001); other factors associated with AI were heart rate (beta=-0.56), mean blood pressure (beta=0.44), height (beta=-0.24), age (beta=0.15), current smoking (beta=0.09), white blood cell count (beta=0.06) and low-density lipoprotein cholesterol (beta=0.06). Similar associations were found when waist circumference (WC, an index of abdominal obesity) was substituted for BMI in the analysis (beta=-0.12, P<0.001). BMI closely correlated with WC (r=0.87), thus suggesting that approximately 76% (a square of 0.87) of BMI can be explained by WC. In conclusion, although it does not have a major impact, obesity, including abdominal obesity, may be an influential factor for reduced radial AI, independently of well-known confounders, in middle-aged Japanese men.