Association of white blood cell parameters with metabolic syndrome: A systematic review and meta-analysis of 168,000 patients.

BACKGROUND:Leukocyte parameters are predicted to be affected in patients with metabolic syndrome (MetS). We conducted a systematic review and meta-analysis to study the association between white blood cell parameters (WBC) in people with and without MetS. METHODS:PubMed, EMBASE, Scopus and Cochrane Library databases were searched according to the study protocol. The standardized mean difference (SMD) and 95% confidence intervals (CI) of leukocyte markers between individuals with and without MetS were pooled using an inverse variance model. Additionally, a subgroup analysis by sex was performed where possible. Methodological quality assessment was conducted using the Newcastle-Ottawa scale (NOS) for observational studies and the Cochrane Risk of Bias tool 2.0 for Randomized Controlled Trials (RCTs). RESULTS:Of 6068 articles identified, 63 were eligible for the study. Compared to controls, individuals with MetS showed significantly higher concentrations of total leukocyte count (SMD [95% CI]: 0.60 [0.55-0.65]; P < .00001; I2 = 100%), neutrophil counts (0.32 [0.28-0.37]; P < .00001; I2 = 99%), lymphocyte counts (0.15 [0.07-0.23]; P = .0004; I2 = 100%), basophil counts (0.01 [0.00-0.02]; P = .02; I2 = 98%), monocyte counts (0.05 [0.02-0.09]; P = .003; I2 = 99%), and neutrophil-to-lymphocyte ratio (0.24 [0.15-0.33]; P < .00001; I2 = 98%). There were no significant differences in the eosinophil count (0.02 [-0.01 to 0.05]; P = .19; I2 = 96%) and monocyte-to-lymphocyte ratio (0.06 [-0.05 to 0.17]; P = .27; I2 = 100%) between patients with and without MetS, however, the lymphocyte-to-monocyte ratio (0.52 [-0.81 to -0.23]; P = .0005; I2 = 52%) tended to be significantly lower in patients with MetS. CONCLUSION:Biomarkers such as total leukocyte count, neutrophil count, lymphocyte count, basophil count, monocyte count and neutrophil-to-lymphocyte ratio are associated with higher levels in patients in MetS and thus can potentially be used for early detection of MetS.