Table 4.
Comparison of GFAP concentrations in plasma vs. serum in outcome subgroups.
| Good outcome | Poor outcome | |||
|---|---|---|---|---|
| (n = 31) | (n = 76) | |||
| Plasma | Serum | Plasma | Serum | |
| Descriptive statistics (pg/mL) | ||||
| Mean | 369.8 | 283.1 | 665.6 | 551.6 |
| Median | 253.9 | 210.6 | 337.3 | 300.5 |
| Standard deviation | 441.9 | 397.5 | 887.0 | 761.6 |
| Interquartile range | 117.1–417.9 | 119.2–314.5 | 221.9–621.1 | 192.4–551.1 |
| Range | 63.4–2318.7 | 48.7–2331.8 | 52.2–4420.0 | 32.6–4813.8 |
| Difference score (plasma – serum) | ||||
| Mean | 86.7 | 113.9 | ||
| Median | 25.5 | 38.5 | ||
| Standard deviation | 205.4 | 408.7 | ||
| Interquartile range | −13.2 to 125.8 | −26.0 to 168.2 | ||
| Range | −94.4 to 1,064.8 | −1,612.0 to 2,083.5 | ||
| Percentage with plasma > serum | 61.3% | 67.1% | ||
| Group comparisons | ||||
| Wilcoxson signed ranks test (z) | 2.63 (p = 0.009) | 3.50 (p < 0.001) | ||
| Effect sizes (r) | 0.47 | 0.40 | ||
| Effect sizes (Cohen's d) | 0.21 | 0.14 | ||
| Spearman correlations | ||||
| Age and GFAP level | 0.559** | 0.756** | 0.435** | 0.406** |
| Time to blood sampling | 0.095 | 0.196 | 0.222 | 0.128 |
| Values from two assays | 0.846** | 0.865** | ||
**
p < 0.01; outcome was defined based on the Glasgow Outcome Scale-Extended (GOS-E), which ranges from 1 to 8, with higher scores indicating better functional outcome. Good outcome was defined as a GOS-E score of 7 (lower good recovery) or 8 (upper good recovery). Poor outcome was defined as a GOS-E score of 6 or lower.