Reference: Front Public Health. 2023 Oct 6:11:1210669
Practice Point: Screening for hypertension is important and we should keep doing it. The value of a new potential predictor of hypertension is less clear.
EBM Pearl: A cross-sectional study cannot predict future risks due to its snapshot-like nature, capturing data at a single point in time without following participants over time. In theory, it should be followed by a prospective cohort study if more information is needed or desired.
Now that we have fully entered pie season, we’d like to introduce the weight-adjusted waist index (WWI), a measure calculated by dividing waist circumference (cm) by the square root of body weight (kg). WWI is hypothesized to be a more precise predictor of cardiovascular and metabolic risk than BMI because it supposedly accounts for age-related changes in body composition.
A recent cross-sectional study published in Frontiers in Public Health evaluated the correlation between WWI and hypertension in adults over age 60 using NHANES data from 2011 to 2018. Hypertension was defined as a mean blood pressure of ≥ 130/80mmHg or self-reported hypertension or use of antihypertensive medications. Three models were used in the analysis with varying degrees of adjustments for covariates including age, gender, race, education level, income to poverty ratio, alcohol use, smoking status, and sedentary behavior.
According to data from 9,329 participants, higher WWI was associated with a higher prevalence of hypertension (p < 0.001) in both the unadjusted and adjusted models. All 3 models demonstrated a stronger association with hypertension for those in the highest WWI quartile. However, a subgroup analysis showed that while there was an association between high WWI and hypertension in adults 60-69 years old, this association didn’t hold up in adults over 70.
Based on the absence of a significant association between WWI and hypertension in older adults (≥70) , these data do not necessarily support the hypothesis that WWI would be a more precise predictor of hypertension than BMI. (To be clear, a direct comparison was not made between WWI and BMI.) There are many study limitations, but let’s put those aside for a moment and just ask, what if WWI were a better predictor of hypertension than BMI? What would that change clinically? We are already checking blood pressures at every visit and counseling patients on healthy diet, exercise, and lifestyle choices. Measuring waist circumference and plugging that into a calculator would require more time when the current pace of medical visits is already harried. When reviewing this study, a nonclinician asked “is there a pill to prevent hypertension?” If only. We might suggest that further research into that quest may be more clinically valuable than a prospective follow-up study of WWI. BMI may not be a perfect predictor of hypertension and other cardiometabolic conditions, but it isn't the predictor that’s broken - it’s the factors that contribute to obesity that need fixing.
For more information, see the topic Risk Factors for Hypertension in DynaMed.
DynaMed EBM Focus Editorial Team
This EBM Focus was written by Elham Razmpoosh, PhD, Postdoctoral fellow at McMaster University, and Katharine DeGeorge, MD, MS, Senior Deputy Editor at DynaMed and Associate Professor of Family Medicine at the University of Virginia. Edited by Alan Ehrlich, MD, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School; Dan Randall, MD, Deputy Editor at DynaMed; Nicole Jensen, MD, Family Physician at WholeHealth Medical; Vincent Lemaitre, PhD, Medical Editor at DynaMed; Hannah Ekeh, MA, Senior Associate Editor at DynaMed; and Jennifer Wallace, BA, Associate Editor at DynaMed.