Stratified subgroup analyses for comparison between studies reporting associations between baseline cognitive impairment and risk of future stroke
| Subgroup | No. of studies | Relative risk (95% CI) | Heterogeneity within subgroups | Heterogeneity among subgroups |
|---|---|---|---|---|
| Cognitive scale score | p < 0.001, I2 = 95% | |||
| MMSE 25–29 or nearest equivalent | 6 | 1.16 (1.06–1.27) | p = 0.8, I2 = 0% | |
| MMSE < 25 or nearest equivalent | 8 | 1.64 (1.46–1.84) | p = 0.08, I2 = 41% | |
| Study design | p = 0.1, I2 = 62% | |||
| Ordinary cohorts | 14 | 1.46 (1.24–1.72) | p < 0.001, I2 = 86% | |
| Analysis of trials | 4 | 1.26 (1.17–1.35) | p = 0.6, I2 = 0% | |
| Sample size | p = 0.5, I2 = 0% | |||
| ≥ 5000 | 9 | 1.34 (1.16–1.55) | p < 0.001, I2 = 87% | |
| < 5000 | 9 | 1.47 (1.20–1.80) | p < 0.001, I2 = 72% | |
| Follow-up duration, yr | p = 0.3, I2 = 17% | |||
| ≥ 5 | 12 | 1.32 (1.11–1.57) | p < 0.001, I2 = 86% | |
| < 5 | 6 | 1.48 (1.31–1.68) | p = 0.002, I2 = 64% | |
| Assessment tool | p = 0.8, I2 = 0% | |||
| MMSE | 10 | 1.38 (1.23–1.55) | p < 0.001, I2 = 67% | |
| Other | 8 | 1.43 (1.13–1.82) | p < 0.001, I2 = 90% | |
| Study location | p = 0.8, I2 = 0% | |||
| North America | 7 | 1.38 (1.02–1.87) | p < 0.001, I2 = 91% | |
| Europe | 7 | 1.47 (1.19–1.81) | p < 0.001, I2 = 76% | |
| Multiple countries or Asian country | 4 | 1.34 (1.22–1.48) | p = 0.07, I2 = 47% | |
| People with prior stroke | p = 0.4, I2 = 0% | |||
| Excluded | 12 | 1.44 (1.18–1.76) | p < 0.001, I2 = 88% | |
| Not excluded | 6 | 1.30 (1.19–1.41) | p = 0.1, I2 = 38% | |
| Study quality | p = 0.4, I2 = 0% | |||
| High, score 5–7 | 10 | 1.29 (1.03–1.62) | p < 0.001, I2 = 88% | |
| Low, score < 5 | 8 | 1.45 (1.30–1.62) | p < 0.001, I2 = 65% |
Note: CI = confidence interval, MMSE = Mini-Mental State Examination.