Short-term Trajectories of Poststroke Cognitive Function: A STROKOG Collaboration Study
Résumé
Background and Objectives Past studies on post-stroke cognitive function have focused on the average performance or change over time, but few have investigated patterns of cognitive trajectories after stroke. This project used latent class growth analysis (LCGA) to identify clusters of patients with similar patterns of cognition scores over the first-year post-stroke and the extent to which long-term cognitive outcome is predicted by the clusters (“trajectory groups”). Methods Data were sought from the Stroke and Cognition consortium (STROKOG). LCGA was used to identify clusters of trajectories based on standardized global cognition scores at baseline (T 1 ) and at the 1-year follow-up (T 2 ). One-step IPD meta-analysis was used to examine risk factors for trajectory groups and association of trajectory groups with cognition at the long-term follow-up (T 3 ). Results Nine hospital-based stroke cohorts with 1149 patients (63% male; mean age 66.4 years (SD=11.0)) were included. The median time assessed at T 1 was 3.6 months post-stroke, 1.0 year at T 2 and 3.2 years at T 3 . LCGA identified 3 trajectory groups, which were characterized by different mean levels of cognition scores at T 1 (low-, -3.27SD (0.94), 17%; medium-, -1.23SD (0.68), 48%; and high-performance, 0.71SD (0.77), 35%). There was significant improvement in cognition for the high-performance group (0.22 SD/year, 95% CI 0.07, 0.36), but changes for the low and medium performance groups were not significant (-0.10 SD/year, 95% CI -0.33, 0.13; 0.11 SD/year, 95% CI -0.08, 0.24 respectively). Factors associated with the low- (versus high-) performance group include age (relative risk ratio [RRR] 1.18, 95% CI 1.14, 1.23), years of education (RRR 0.61, 95% CI 0.56, 0.67), diabetes (RRR 3.78, 95% CI 2.08, 6.88), large artery versus small vessel strokes (RRR 2.77, 95% CI 1.32, 5.83), and moderate/severe strokes (RRR 3.17, 95% 1.42, 7.08). Trajectory groups were predictive of global cognition at T 3 , but its predictive power was comparable to scores at T 1 . Conclusion The trajectory of cognitive function over the first-year post-stroke is heterogenous. Baseline cognitive function ∼3.6 months post-stroke is a good predictor of long-term cognitive outcome. Older age, lower levels of education, diabetes, large artery strokes, and greater stroke severity are risk factors for lower cognitive performance over the first year.