Association of white blood cell count-to-mean platelet volume ratio with the risk of fatal stroke occurrence in older Chinese

White blood cell (WBC) and mean platelet volume (MPV) counts are related to stroke events, but relationship between their combined indicator (WBC count-to-MPV count ratio (WMR)) and the risk of fatal stroke occurrence is unclear so far. In this prospective analysis, we enrolled 27,163 participants aged 50 years or older without a stroke history in the Guangzhou Biobank Cohort Study. After a mean follow-up time of 15.0 (SD = 2.2) years with 389,242 person-years, 816 stroke (401 ischaemic, 259 haemorrhagic and 156 unclassified) deaths were recorded. Cox’s proportional hazards regression was used to estimate the hazard ratios (HRs) and the 95% confidence intervals (CIs). Compared with those in the lowest quartile, participants with the highest WMR had different risks for fatal all stroke and fatal ischaemic stroke, respectively, although an increased risk for fatal ischaemic stroke was observed among participants in the fourth WMR quartile and further hs-CRP adjustment; those in the WMR change with 10% increase had a 36% increased risk of fatal all stroke and a 79% increased risk of fatal haemorrhagic stroke, compared to those in a stable (the WMR change between −10% and 10%). Our findings suggest that higher WMR and its longitudinal change were associated with an increased risk of fatal stroke occurrence in middle-aged to older Chinese; it may be a potential indicator for the future fatal stroke occurrence in relatively healthy elderly populations.