Waist-to-height ratio as an indicator of early health risk: Simpler and more predictive than using a matrix based on BMI and waist circumference

Abstract

Objectives: There is now good evidence that central obesity carries more health risks compared with total obesity assessed by body mass index (BMI). It has therefore been suggested that waist circumference (WC), a proxy for central obesity, should be included with BMI in a ematrixf to categorise health risk. We wanted to compare how the adult UK population is classified using such a ematrixf with that using another proxy for central obesity, waist-to-height ratio (WHtR), using a boundary value of 0.5. Further, we wished to compare cardiometabolic risk factors in adults with ehealthyf BMI divided according to whether they have WHtR below or above 0.5. Setting, participants and outcome measures: Recent data from 4 years (2008.2012) of the UK National Diet and Nutrition Survey (NDNS) (n=1453 adults) were used to cross-classify respondents on anthropometric indices. Regression was used to examine differences in levels of risk factors (triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), TC: HDL, glycated haemoglobin (HbA1c), fasting glucose, systolic (SBP) and diastolic blood pressure (DBP)) according to WHtR below and above 0.5, with adjustment for confounders (age, sex and BMI). Results: 35% of the group who were judged to be at eno increased riskf using the ematrixf had WHtR .0.5. The ematrixf did not assign eincreased riskf to those with a ehealthyf BMI and ehighf waist circumference. However, our analysis showed that the group with ehealthyf BMI, and WHtR .0.5, had some significantly higher cardiometabolic risk factors compared to the group with ehealthyf BMI but WHtR below 0.5. Conclusions: Use of a simple boundary value for WHtR (0.5) identifies more people at eearly health riskf than does a more complex ematrixf using traditional boundary values for BMI and WC. WHtR may be a simpler and more predictive indicator of the eearly heath risksf associated with central obesity.