NIHSS is not enough for cognitive screening in acute stroke: A cross-sectional, retrospective study
Tamar Abzhandadze, Malin Reinholdsson, Katharina S. Sunnerhagen
Abstract
The aim of this study was to investigate whether the cognitive subscale of the National Institute of Health Stroke Scale (NIHSS), the Cog-4, can detect cognitive deficits in acute stroke. This was a cross-sectional, retrospective study. The study sample consisted of people with stroke enrolled in an acute stroke unit. The index test Cog-4 was calculated based on admission NIHSS score. The reference standard instrument, the Montreal Cognitive Assessment (MoCA), was performed within 36-48 h of admission. Non-parametric statistics were used for data analyses. The study included 531 participants with a mean age of 69 years. The Cog-4 failed to identify cognitive deficits in 65%, 58%, and 53% of patients when the MoCA thresholds for impaired cognition were set at ≤25 p, ≤23 p, and ≤19 p, respectively, were chosen for impaired cognition. The agreement between the Cog-4 and the MoCA was poor; Cohen's kappa was from -0.210 to -0.109, depending on the MoCA cut-offs. The sensitivity of the Cog-4 was 35%, 42% and 48% for the MoCA thresholds for impaired cognition ≤25, ≤23 and ≤19 points, respectively. The Cog-4 has a limited ability to identify cognitive deficits in acute stroke. More structured and comprehensive tests should be employed as diagnostic tools.