Study on Waist-to-Height Ratio and NAFLD

Results of a new study suggest that in adults, the waist-to-height ratio is associated with NAFLD, and the association is not purely linear but non-linear, with significant threshold and saturation effects. The findings have been published in BMC Gastroenterology.

The waist circumference (WC) and body mass index (BMI) are currently the most widely used anthropometric indicators to assess obesity worldwide and are also the most critical risk factors for NAFLD. These indicators are simple to measure and provide excellent convenience to prevent and manage many diseases. However, in recent years, in-depth studies have found that the waist-to-height ratio (WHtR) can better assess the risk of central obesity, diabetes, hypertension, and other metabolic diseases. Furthermore, several recent cross-sectional studies have shown that WHtR is a stronger predictor of NAFLD risk and its severity and is more sensitive to diagnosis than WC and BMI. However, few studies have investigated the association between WHtR and NAFLD, which contain deeper relationships, such as non-linear relationships, and whether a special population exists among different subgroups. Additionally, the sample sizes of several existing studies on the association between WHtR and NAFLD are relatively small. Therefore, this study aimed to further explore and analyze the association between WHtR and NAFLD in adults using a large sample size.

For the current study, the cross-sectional study population was from a large-scale health examination programme called 'human dock' in Japan. In this study, 14,125 participants in this health examination programme were included. To understand the association between the WHtR and NAFLD more intuitively, researchers grouped the WHtR values into quintiles and used a multivariable logistic regression model to assess WHtR and its quintile with NAFLD risk. Moreover, the team used the generalised additive model to model the association between WHtR and NAFLD to explore their non-linear relationship.

Results

• The prevalence of NAFLD among participants in this study was 17.59%, with an average age of 43.53 ± 8.89 years.
• After adjusting for all non-collinear covariables, a 66% increase in the NAFLD risk per SD increase in WHtR was observed.
• In the quintile groups of WHtR, the participants in quintile 2, quintile 3, quintile 4, and quintile 5 had 3.62-fold, 5.98-fold, 9.55-fold, and 11.08-fold increased risks of NAFLD, respectively, compared with those in quintile 1 (Ptrend < 0.0001).
• Non-linear relationship analysis revealed threshold and saturation effects between WHtR and NAFLD in which a WHtR of approximately 0.4 might be the threshold effect of NAFLD risk, 0.6 might be the saturation effect of NAFLD risk.
• Subgroup analysis showed that the interaction between WHtR and BMI was significant.

"This study's advantage is that, based on a large sample size, a standard questionnaire was used to evaluate the habit of exercise as an important risk factor, and a rigorous statistical adjustment was made to explore the association between WHtR and NAFLD deeply. Additionally, this study is the first to confirm that the association between WHtR and NAFLD is non-linear and provides a reference range of WHtR associated with NAFLD risk," the team concluded.

For the full article, follow the link: https://doi.org/10.1186/s12876-021-01824-3

Primary source: BMC Gastroenterology