Recurrence of Chronic Subdural Hematoma Is Independent of ABO Blood Type: A Retrospective Cohort Study

OBJECTIVE: A previous study with a limited number of patients has shown that blood type A was a risk factor in the recurrence of CSDH. The primary objective of this study was to investigate the association between the recurrence of CSDH and ABO blood type based on a larger sample size. METHODS: The authors reviewed in-patients with symptomatic CSDH from August 2011 to August 2021. Hospitalization information and data on long-term outcomes and recurrence among these patients were gathered. For all clinical variables, numbers (percentages) and mean ± standard deviations were used for categorical and continuous variables, respectively. For intergroup comparisons, the χ2 test or one-way ANOVA was carried out. Multivariable logistic regression analyses were performed to identify the association between CSDH recurrence and blood types. RESULTS: We included 1,556 inpatients in this study. The recurrence rate of CSDH showed no differences among different blood types. In the multivariable logistic regression analyses, ABO blood type (A: OR, 1.064; 95% CI, 0.467–2.851, p = 0.793; B: OR, 0.682, 95% CI, 0.315–1.269, p = 0.164; AB: OR, 0.537, 95% CI, 0.426–1.861, p = 0.357) was not a significantly independent predictor of CSDH recurrence. CONCLUSIONS: Our study demonstrated that ABO blood type was not a risk factor in the recurrence of CSDH. Thus, we should not pay too much attention to ABO blood type in terms of CSDH recurrence.