Dose-response analysis between weight-adjusted waist index and all-cause and cardiovascular mortality: a systematic...

The weight-adjusted waist index (WWI), calculated as waist circumference divided by the square root of body weight (cm/ $\surd$ kg), has been proposed as an anthropometric index reflecting central adiposity relative to body weight. However, its association with all-cause and cardiovascular (CV) mortality remains incompletely characterized.

We systematically searched PubMed, Embase, Web of Science, Scopus, and Medline from inception to April, 2026, for cohort studies evaluating WWI and all-cause or CV mortality. Hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled using random-effects models. To avoid pseudo-replication from overlapping public database-derived cohorts, particularly NHANES, the primary analysis was based on non-overlapping cohorts. Risk of bias was assessed using the Newcastle-Ottawa Scale, and certainty of evidence was evaluated using the GRADE framework.

A total of 47 studies were included. In the primary non-overlapping analyses, each 1 cm/ $\surd$ kg increment in WWI was associated with a higher risk of all-cause mortality (HR = 1.21, 95% CI: 1.14-1.28; I ² = 83.5%) and CV mortality (HR = 1.27, 95% CI: 1.18-1.35; I ² = 60.8%). Comparing the highest with the lowest WWI categories yielded pooled HRs of 1.40 (95% CI: 1.22-1.61) for all-cause mortality and 1.54 (95% CI: 1.22-1.94) for CV mortality. Dose-response meta-analyses suggested a positive association compatible with a linear pattern. Although most included studies were of moderate to high methodological quality based on the NOS, the overall GRADE certainty of evidence was rated low for all-cause mortality and moderate for CV mortality, due to substantial between-study heterogeneity and potential publication bias.

Higher WWI is positively associated with an increased risk of all-cause and CV mortality. WWI may serve as a useful epidemiological marker of adiposity-related mortality risk. However, given the observational nature of the evidence and substantial heterogeneity, further research with formal predictive performance evaluations is required to determine whether WWI improves individual-level risk prediction beyond traditional anthropometric indices.