The findings of previous studies that compared the predictive power of anthropometric measures to predict cardiometabolic conditions are contradicting. Our study demonstrated a higher ability for WHtR to predict diabetes and hypertension among Jordanian adult men and women compared to other measures. This finding is consistent with the findings of other studies that showed WHtR a better predictor compared to other measures among women (8-10) and men (11) of different populations including a meta-analysis (12) of ten studies and a systematic review of 13 studies which demonstrated superiority of WHtR over other measures (13). WHtR has been argued to be superior to a single measure of WC by taking into account intraindividual and ethnic differences in height (6). However, there was a lot of inconsistency regarding the different anthropometric measures in predicting diabetes and hypertension. WHR was reported to be a better predictor in a number of countries (14-17). Also, WC was reported to show superiority over other anthropometric measures in the prediction of type 2 diabetes in British women (18), U.S. men (19), German women (11), and Indian men and women (20).
Regarding BMI, systematic reviews (6, 21) encompassing Asian and Caucasian populations have consistently reported the inferior utility of BMI in identifying undiagnosed diabetes as compared with abdominal indices.
On the other hand, other studies demonstrated that BMI, WHR, WC, and WHtR had similar predictive powers for the risk of type 2 diabetes (24). WHR, WC, and WHTR performed similarly well in Bangladeshi women (23). A meta-analysis of 32 studies (24) showed that BMI, WHR, and WC had similar associations with incident diabetes.
Possible reasons for variation between studies might be due to ethnic and racial differences and differences in body composition and fat distribution between different ethnic groups, genders and age groups. Other reasons might include different study designs, different WC measurement protocols or different methods for defining cardiometabolic outcomes.
The appropriate cut-off points for predicting diabetes and hypertension among Jordanian women were 92 cm form WC, 104 cm for HC, 30 Kg/m2 for BMI, 0.85 for WHR, and 0.60 for WHtR. For men, the appropriate cut-off points were 100 cm for WC, 104 cm for HC, 27 Kg/m2 for BMI, 0.93 for WHR, and 0.57 for WHtR. Different cut-off values were reported for other populations. Ethnic and racial differences might explain the discrepancy in cut-off values between different studies.
The findings of ROC analysis in this study are supported by findings of the age-adjusted associations of dichotomized anthropometric measures with the outcome variables. WHtR and WC, using the established cut-off values, had strong association with previously and recently diagnosed diabetes and hypertension.
Our study had several strengths including a large national sample. In addition, the anthropometric measures were performed by the same team of field researchers. The main limitation of this study is the lower response rate (40%) in males. This is expected given that the employment rate in men in Jordan is much higher than that in women. An important limitation to consider when interpreting the findings is the possibility of measurement error (e.g. we measured the WC over light clothing). Another limitation is that the predictive ability of these anthropometric measures is correlated or associated with cardiovascular disease risk factors but not with cardiovascular disease events itself. So further studies are needed to correlate these measures with actual events.