Sagittal abdominal diameter: A novel and potentially superior indicator than waist circumference for diagnosis of central obesity, based on evidence from multiple data sources

Abstract

Background and aims: Our previous research reported a visceral fat area (VFA) estimation equation primarily based on sagittal abdominal diameter (SAD), demonstrating favorable performance compared to traditional Waist Circumference (WC)-based equations. While WC is widely used for central obesity measurement, its accuracy needs improvement. This study aims to investigate whether SAD has advantages over WC in diagnosing central obesity and to determine the optimal cut-off values for diagnosis.

Methods: This cross-sectional, retrospective cohort study analyzed 6762 individuals from NHANES (2011-2016) and 701 from Chinese health examinations (2023). ROC curve analysis compared AUC of different indicators in identifying two or more non-adipose components of Metabolic Syndrome (MetS).

Results: SAD exhibited the strongest correlation with VFA and demonstrated the strongest associations with most metabolic parameters compared to WC and BMI. Furthermore, compared with WC, SAD had significantly higher AUC values in diagnosing two or more non-adipose components of MetS, with the difference being significant in the NHANES database population (all p < 0.001). The optimal SAD cut-off value was approximately 21.0 cm for both genders and populations, with MetS prevalence increasing rapidly at SAD≥22.0 cm. Subgroup analysis of NHANES revealed variations in optimal SAD cut-off values: Other Races (23.7 cm), Non-Hispanic Black females (18.8 cm), and other subgroups (20.0-22.0 cm).

Conclusion: SAD demonstrates higher efficacy than WC in diagnosing central obesity, suggesting its suitability for assessing central obesity. Additionally, SAD shows potential for a unified diagnostic cut-off value across genders and regions.

Keywords: Central obesity; Sagittal abdominal diameter; Visceral fat area; Waist circumference.