Gender differences in the impact of metabolic syndrome components on mortality in older people: A systematic review and meta-analysis

Background and aims: The influence of metabolic syndrome (MetS) on mortality may be influenced by age- and gender-related changes affecting the impact of individual MetS components. We investigated gender differences in the association between MetS components and mortality in community-dwelling older adults. Methods and results: Prospective studies were identified through a systematic literature review up to June 2019. Random-effect meta-analyses were run to estimate the pooled relative risk (RR) and 95% confidence intervals (95% CI) of all-cause and cardiovascular (CV) mortality associated with the presence of MetS components (abdominal obesity, high triglycerides, low HDL cholesterol, high fasting glycemia, and high blood pressure) in older men and women. Meta-analyses considering all-cause (103,859 individuals, 48,830 men, 55,029 women; 10 studies) and CV mortality (94,965 individuals, 44,699 men, 50,266 women; 8 studies) did not reveal any significant association for abdominal obesity and high triglycerides in either gender. Low HDL was associated with increased all-cause (RR = 1.16, 95% CI: 1.02–1.32) and CV mortality (RR = 1.34, 95% CI: 1.03–1.74) among women, while weaker results were found for men. High fasting glycemia was associated with higher all-cause mortality in older women (RR = 1.35, 95% CI: 1.22–1.50) more than in older men (RR = 1.21, 95% CI: 1.13–1.30), and CV mortality only in the former (RR = 1.36, 95% CI: 1.04–1.78). Elevated blood pressure was associated with increased all-cause mortality (RR = 1.16, 95% CI: 1.03–1.32) and showed marginal significant results for CV death only among women. Conclusions: The impact of MetS components on mortality in older people present some gender differences, with low HDL cholesterol, hyperglycemia, and elevated blood pressure being more strongly associated to all-cause and CV mortality in women.