Postoperative recurrence of chronic subdural hematoma is more frequent in patients with blood type A

Because of an aging society, the incidence of chronic subdural hematoma (CSDH) is increasing. This lesion is treated with simple burr hole irrigation, but one of the major issues is that CSDH frequently recurs. ABO blood type may be associated with a bleeding tendency and inflammation. However, its association with the recurrence of CSDH remains unknown. Therefore, the authors of the present study aimed to retrospectively investigate the association between ABO blood type and CSDH recurrence.

The authors retrospectively analyzed symptomatic CSDHs in 425 cerebral hemispheres of 376 patients who had undergone surgical treatment with irrigation of the hematoma via burr holes at their institution from January 2011 to September 2019. Among these were 366 CSDHs in 320 patients whose ABO blood type had been determined and who were included in this study.

In the study, 307 patients with CSDHs in 350 hemispheres were followed up postoperatively until the disappearance of the CDSH or for at least 3 months. Recurrence of CSDH was observed in 37 patients (10.6%) after surgical treatment. Blood type A was found to be significantly associated with CSDH recurrence compared to non-A blood types: 24 of 153 CDSHs (15.7%) versus 13 of 197 CDSHs (6.6%) (p = 0.008). In the multivariable regression analysis, blood type A, in addition to thrombocytopenia, was a significant independent predictor of the recurrence of CSDH.

The study results showed that blood type A is an independent risk factor for the postoperative recurrence of CSDH and that careful follow-up in these patients may be needed.