Design and validation of a novel estimator of visceral adipose tissue area and comparison to existing adiposity surrogates.

AIMS: Visceral adiposity measured by computed tomography (CT) as intra-abdominal fat area (IAFA) predicts metabolic diseases. Existing adiposity surrogates have not been systematically compared to a regression-based model derived in individuals of Japanese ancestry. We developed and validated a method to estimate IAFA in individuals of Japanese ancestry and compared it to existing adiposity surrogates. METHODS: We assessed age, BMI, waist circumference (WC), fasting lipids, glucose, smoking status, grip strength, mid-thigh circumference (MTC), humeral length, leg length, and IAFA by single-slice CT at the umbilicus for 622 Japanese Americans. We used stepwise linear regression to predict IAFA and termed the predicted value the Estimate of Visceral Adipose Tissue Area (EVA). For men, the final model included age, BMI, WC, high-density lipoprotein cholesterol (HDLc), glucose, and MTC; for women, age, BMI, WC, HDLc, low-density lipoprotein cholesterol, glucose, and MTC. We compared goodness-of-fit (R2) from linear regression models and mean-squared errors (MSE) from k-fold cross-validation to compare the ability of EVA to estimate IAFA compared to an estimate by Després et al., waist-to-height ratio, WC, deep abdominal adipose tissue index, BMI, lipid accumulation product, and visceral adiposity index (VAI). We classified low/high IAFA using area under receiver-operating characteristic curves (AUROC) for IAFA dichotomized at the 75th percentile. RESULTS: EVA gave the least MSE and greatest R2 (men: 1244, 0.61; women: 581, 0.72). VAI gave the greatest MSE and smallest R2 (mean 2888, 0.08; women 1734, 0.14). CONCLUSIONS: EVA better predicts IAFA in Japanese-American men and women compared to existing surrogates for adiposity.

Association of Visceral Fat and Liver Fat With Hyperuricemia.

OBJECTIVE: To examine cross-sectionally whether intraabdominal fat area (IAFA), i.e., visceral fat, and liver fat assessed by computed tomography (CT) are independently associated with hyperuricemia. METHODS: Subjects were 801 Japanese men not taking antidiabetic, antihypertensive, or urate-lowering medications, without any history of renal disease, cardiovascular disease, or cancer, and with serum creatinine <1.5 mg/dl. Abdominal, thoracic, and thigh fat areas were measured by CT. Total fat area (TFA) was the sum of these fat areas. Total subcutaneous fat area (TSFA) was TFA minus IAFA. Liver fat was assessed by liver-to-spleen (L/S) ratio measured by CT. Hyperuricemia was defined as serum uric acid level >7.0 mg/dl. Its association with adiposity was tested using logistic regression. RESULTS: The prevalence of hyperuricemia was 19.6% (157 men). Both greater IAFA and lower L/S ratio were independently associated with hyperuricemia in models that simultaneously included IAFA and L/S ratio: multiple-adjusted odds ratios of hyperuricemia for quintiles 3, 4, and 5 of IAFA were 2.16 (95% confidence interval [95% CI] 1.02-4.59), 2.41 (95% CI 1.13-5.16), and 4.00 (95% CI 1.81-8.85), respectively, compared to quintile 1, and the L/S ratios for quintiles 3, 2, and 1 were 2.34 (95% CI 1.16-4.75), 2.15 (95% CI 1.06-4.34), and 2.79 (95% CI 1.35-5.76), respectively, compared to quintile 5. Both IAFA and L/S ratio remained significant even after adjusting for abdominal subcutaneous fat area, TFA, TSFA, body mass index, or waist circumference. Of all fat measurements, IAFA had the strongest association with hyperuricemia by Akaike's information criteria. CONCLUSION: Greater amounts of both visceral fat and liver fat were independently associated with hyperuricemia.

Visceral adiposity, not abdominal subcutaneous fat area, is associated with high blood pressure in Japanese men: the Ohtori study.

Visceral adiposity is considered to have a key role in cardiometabolic diseases. The purpose of this study is to investigate cross-sectionally the association between intra-abdominal fat area (IAFA) measured by computed tomography (CT) and high blood pressure independent of abdominal subcutaneous fat area (ASFA) and insulin resistance. Study participants included 624 Japanese men not taking oral hypoglycemic medications or insulin. Abdominal, thoracic and thigh fat areas were measured by CT. Total fat area (TFA) was calculated as the sum of abdominal, thoracic and thigh fat area. Total subcutaneous fat area (TSFA) was defined as TFA minus IAFA. Hypertension and high normal blood pressure were defined using the 1999 criteria of the World Health Organization. Multiple-adjusted odds ratios of hypertension for tertiles of IAFA were 2.64 (95% confidence interval, 1.35-5.16) for tertile 2, and 5.08 (2.48-10.39) for tertile 3, compared with tertile 1 after adjusting for age, fasting immunoreactive insulin, diabetes status, ASFA, alcohol consumption, regular physical exercise and smoking habit. IAFA remained significantly associated with hypertension even after adjustment for ASFA, TSFA, TFA, body mass index or waist circumference, and no other measure of regional or total adiposity was associated with the odds of hypertension in models, which included IAFA. Similar results were obtained for the association between IAFA and the prevalence of high normal blood pressure or hypertension. In conclusion, greater visceral adiposity was associated with a higher odds of high blood pressure in Japanese men.