The effectiveness of 24 weeks healthy eating and weight management counselling on body composition among middle aged Hong Kong Chinese women: a randomized controlled trial

Background:
Limited studies have investigated the threshold effects of the associations between anthropometric indexes and the risk of cardiovascular disease (CVD) in Asian female population. The purposes of this study were to examine the associations of 10-year CVD risk with waist circumference (WC), hip circumference (HC), thigh circumference (TC), and waist-hip-ratio (WHR) in a sample of Hong Kong Chinese women and to explore the possible threshold effects.

Method:
Baseline data of a population-based prospective cohort study were analyzed. The cohort enrolled 4,222 Hong Kong women aged from 30 to 74 years and free of CVD since 2019. In total 3,809 (90.22%) women who had physical examinations (blood pressure, height, weight, WC, HC and TC) and lipid test (cholesterol, high density lipoprotein) were included in the analysis. Other variables including demographics, disease status, lifestyle factors were collected by questionnaires through face-to-face interview. The 10-year CVDs risk was calculated by the laboratory-based Framingham 10-year risk score (FRS). Multiple linear regression model was adopted to explore the relationships between anthropometric variables and 10-year CVD risks. Two-piecewise linear regression model was further used to exam the threshold effect, with breakpoint automatically calculated by recursive algorithm.

Result:
The average age of the participants was 55.8±8.8 years and most of them were middle-aged (75.4%). The percentage of overweight and obesity was 20.2% and 25.4%, respectively. The mean waist and hip circumference was 78.89±9.40 cm and 94.7±6.7 cm. The median score of FRS was 0.05 (IQR: 0.03 to 0.08), and 14.9% of the participants had a high level of CVD risk (FRS ≥ 10%). After adjustment of BMI, education level, employment status, physical activity and alcohol use, 1-cm increase in WC was associated with 0.13 (95% CI: 0.10 to 0.16) units increase in FRS; while 1-cm increase in HC and TC predicted -0.23 (95% CI: -0.27 to -0.20) and -0.25 (95% CI: -0.28 to -0.21) units changes of FRS, respectively. The WHR showed positive association with FRS (β= 19.5, 95% CI: 17.27 to 21.72). Threshold effects existed in all the four anthropometric parameters. After adjustment of corresponding covariates, the regression coefficient was 13.1 (95% CI: 7.93 to 18.28) when the WHR was less than 0.81 and became stronger when the WHR was larger than 0.81 (β=23.23, 95% CI: 18.88 to 27.59), which leads to an increasement of 77.19%. Similar findings were observed for other anthropometric parameters, with a breakpoint of 88cm, 102.3cm and 53.5cm for WC, HC and TC, respectively (Table 1).

Conclusion:
Larger WC but smaller HC and TC predicted the higher 10-year CVD risk in Hong Kong Chinese women. When the WC and WHR excess a threshold value (i.e., 88 cm and 0.81), the 10-year CVD risk was aggravated.