Elevated white blood cell counts and risk of metabolic syndrome: a dose-response meta-analysis

Elevated white blood cell count has been a known risk factor for cardiovascular diseases. Cardiometabolic diseases have some risk factors in common. Therefore, we assessed the association between elevated white blood cell counts and risk of metabolic syndrome using dose-response meta-analysis method.
Materials & We searched for observational studies including white blood cell counts as exposure and metabolic syndrome as outcome through international databases (PubMed, Embase, and Scopus) up to October 2017. Multi-adjusted odds ratio (OR) and corresponding 95% confidence intervals (CIs) were extracted from eligible articles. Random-effects model was used to estimate the relationship between elevated white blood cell counts and risk of metabolic syndrome. After independent screening, 17 studies were selected and included in this meta-analysis. Compared with lowest quartile of white blood cell, OR for highest quartile was 2.35 (CI 1.81 to 3.05). Ten studies were included in dose-response meta-analysis and the result showed OR 1.21 (CI 1.10 to 1.34) per unit increase (1000 ml) in white blood cell counts. We did not find any evidence of publication bias using Egger’s regression (P=0.11). This meta-analysis suggested that there might be a dose response association between higher white blood cell count as an inflammatory factor and increased risk of metabolic syndrome. Also risk of metabolic syndrome is higher in the women and individuals of older age. In order to draw causal inference propective studies using genetic factors will be necessary.