Optimal cut-off values and population means of waist circumference in different populations

Abstract

Abdominal obesity is a risk factor for cardiometabolic disease, and has become a major public health problem in the world. Waist circumference is generally used as a simple surrogate marker to define abdominal obesity for population screening. An increasing number of publications solely rely on the method that maximises sensitivity and specificity to define 'optimal' cut-off values. It is well documented that the optimal cut-off values of waist circumference vary across different ethnicities. However, it is not clear if the variation in cut-off values is a true biological phenomenon or an artifact of the method for identifying optimal cut-off points. The objective of the present review was to assess the relationship between optimal cut-offs and population waist circumference levels. Among sixty-one research papers, optimal cut-off values ranged from 65·5 to 101·2 cm for women and 72·5 to 103·0 cm for men. Reported optimal cut-off values were highly correlated with population means (correlation coefficient: 0·91 for men and 0·93 for women). Such a strong association was independent of waist circumference measurement techniques or the health outcomes (dyslipidaemia, hypertension or hyperglycaemia), and existed in some homogeneous populations such as the Chinese and Japanese. Our findings raised some concerns about applying the sensitivity and specificity approach to determine cut-off values. Further research is needed to understand whether the differences among populations in waist circumference were genetically or environmentally determined, and to understand whether using region-specific cut-off points can identify individuals with the same absolute risk levels of metabolic and cardiovascular outcomes among different populations.

Waist circumference and risk of cardiovascular disease, type 2 diabetes and mortality among Aboriginal adults in an Australian community

“…The WC values for overweight and central obesity from BMI determined in this study will contribute to evidence required for WC cut-off if the risk is considered high enough to take actions (13).…”

“…WC cut-points in several populations worldwide (13,228). Wang et al conducted a literature review of 75 relevant articles defining WC cut-off points in different populations worldwide using the ROC approach (13).…”

“…Wang et al conducted a literature review of 75 relevant articles defining WC cut-off points in different populations worldwide using the ROC approach (13). They found the derived WC cut-off points from ROC do not take into account variations in WC levels.…”

“…This approach has its limitations in the differences in cut-off points based on differences in population characteristics such as average body size or disease prevalence (138). As noted by Wang et al (13,229), this method will not give a consensus on WC cut-off values for Aboriginal people in Australia due to the variations in WC mean values in different communities (12) which also changes over time in the same community.…”

“…However, this method may over-simplify the complexity for defining WC cut-off values, as optimal cut-offs vary substantially across populations, with variations mainly driven by the population WC mean levels (13). Therefore, in relation to the substantial differences in WC mean values in diverse Aboriginal communities (subpopulations), a consensus might not be reached with the application of the currently used optimising method as optimal WC cut-off values will vary across different communities.…”