Mendelian randomization estimates for the association of higher genetically predicted cerebrospinal fluid (CSF) haptoglobin with catastrophic aneurysmal subarachnoid haemorrhage (aSAH) in multi-ancestry and White British only UK Biobank participants.

Mendelian randomization (MR) estimates are expressed as odds ratio per one standard deviation higher genetically predicted CSF haptoglobin. Higher genetically predicted CSF haptoglobin was associated with lower risk of catastrophic aSAH using inverse variance weighted and weighted median MR methods. There was no evidence of pleiotropy or heterogeneity, as indicated by the non-significant Egger intercept and Q-statistic.