Minimum Clinically Important Difference of Montreal Cognitive Assessment in aneurysmal subarachnoid hemorrhage patients

Cognitive impairment is a major factor contributing to poor functional outcome after subarachnoid hemorrhage caused by a ruptured cerebral aneurysm (aSAH). Montreal Cognitive Assessment (MoCA) has been shown to be superior to the Mini-Mental State Examination in screening for cognitive domain deficit and correlating to functional outcome in aSAH patients. The aim of the current study was to determine the Montreal Cognitive Assessment (MoCA) score change that was associated with change of health in general in an aSAH patient cohort. We recruited aSAH patients from a regional neurosurgical center over a 3-year period. Patient assessments including MoCA and global rating of change (GRoC) were carried out at at 3 and 12 months after aSAH. Anchor-based and distribution-based approaches were adopted to calculate the Minimum Clinically Important Difference (MID). One hundred and seventy-five aSAH patients completed both 3-month and 1-year assessments and consented for participation. Employing the distribution-based approach for the 3-month and 1-year MoCA scores, the MID estimates equated to a change of 2.0 and 1.1 respectively. Employing the anchor-based approach (with GRoC), the MID estimate of MoCA (median, IQR) was 2, 1-4. In conclusion, we found that the MID of MoCA score associated with change of health in general in aSAH patients was 2. The MID provides guidance for future clinical trial design targeting on cognitive dysfunction after aSAH.