Obesity paradox, weight-free anthropometric measures, and major adverse cardiovascular events in the elderly: Insight from the Northern Shanghai Study

Abstract Aims Many studies have investigated the obesity paradox in the elderly. However, besides body mass index (BMI), many other anthropometric measures, such as the waist-to-hip ratio (WHR), provide a better indication of body fat distribution and may be more useful in a geriatric population. Methods 3285 participants aged over 65 years old from the Northern Shanghai Study were included in this analysis. Eight anthropometric measures, including weight-related measures (BMI, weight-adjusted-waist index, body shape index and body surface area) and weight-free measures (WHR, waist-to-height ratio, body roundness index, relative fat mass) were measured and calculated with standard methods. Major adverse cardiovascular events (MACEs) included the non-fatal myocardial infarction, non-fatal stroke or cardiovascular death. Results Participants had an average age of 71.4 years and 1428 (43.47%) were men. The median follow-up was 5.4 years (IQR, 4.4-7.3 years) and 218 events occurred. Participants with obesity (BMI ≥ 28 kg/m2) were associated with a higher risk of MACEs compared with the normal (adjusted Hazard ratio = 1.54, 95% confidence interval (CI): 1.07-2.22, P=0.020). Restricted cubic splines also highlighted the robust correlation between high BMI and high MACEs risk (Pfor overall=0.025, Pfor nonlinear=0.339). Similarly, the aHR for the incidence of MACEs in WHR quartile 4 versus quartile 1 was 1.96 (95% CI: 1.26-3.05, P=0.003). When WHR was examined as a continuous variable, the result remained unaltered (Pfor overall=0.020, Pfor nonlinear=0.353). In adjusted model, all four weight-free measures were significantly associated with increased risk of MACEs (all P<0.05), while only two weight-related measures were related to the risk of MACEs. Conclusion In the elderly, BMI and alternative anthropometric measures showed no evidence of an "obesity paradox". Weight-free measures were more relevant to a risk of MACEs.Take home message