Association Between Red Blood Cell Distribution Width and All-cause Mortality in Chronic Kidney Disease Patients: A Systematic Review and Meta-analysis.

BACKGROUND: Considering results among previous studies regarding the relationship of red blood cell distribution width (RDW) and all-cause mortality in chronic kidney disease (CKD) patients, we aimed to perform a comprehensive meta-analysis to evaluate the potential association between RDW and all-cause mortality in CKD patients.

METHODS: We conducted a systematic literature using electronic databases (PubMed, Ovid, Embase and Web of Science) to identify the studies reporting the association between RDW and all-cause mortality in CKD patients. We searched the literatures published December 2016 or earlier. We used both fix-effects and random-effects models to calculate the overall effect estimate. A sensitivity analysis and subgroup analysis were performed to find the origin of heterogeneity.

RESULTS: We retrieved 9 studies with a total of 117,047 patients. For every 1% increase in RDW, the risk of all-cause mortality increased by 47% (HR 1.47, 95% CI 1.35-1.61) with no statistical heterogeneity among the studies (I2  = 44.5%, p = 0.094). When RDW was entered as a categorical variable, mortality risk was significantly increased (HR 1.84, 95% CI 1.21-2.81). Heterogeneity among the studies was observed for all-cause mortality (I2  = 82.3%, p = 0.001). We also performed a predefined subgroup analyses according to study population. We found that for every 1% increase in RDW, the risk of all-cause mortality in hemodialysis (HD) patients increased by 36% (HR 1.36, 95% CI 1.20-1.53).

CONCLUSIONS: Our meta-analysis suggests that high levels of RDW probably increase the risk of all-cause mortality in CKD patients.