Table 3. Subgroup analyses of the relationship between CD8+ T lymphocyte subsets and OS.
| Outcome subgroup | Study number | Case number | HR (95% CI) | Model | P value | Heterogeneity | |
|---|---|---|---|---|---|---|---|
| I2 (%) | P value | ||||||
| Ethnicity | |||||||
| Asian | 12 | 2,035 | 0.72 (0.62–0.83) | Fixed | <0.00001 | 0 | 0.45 |
| Caucasian | 5 | 494 | 0.58 (0.44–0.76) | Fixed | <0.0001 | 9 | 0.36 |
| Histology | |||||||
| ESCC | 10 | 1,700 | 0.74 (0.63–0.87) | Fixed | 0.0005 | 14 | 0.32 |
| EAC | 4 | 424 | 0.67 (0.46–0.98) | Fixed | 0.04 | 8 | 0.35 |
| Both | 3 | 405 | 0.59 (0.47–0.74) | Fixed | <0.00001 | 0 | 0.57 |
| Sample size | |||||||
| <100 | 5 | 436 | 0.57 (0.33–0.98) | Random | 0.11 | 60 | 0.04 |
| >100 | 12 | 2,093 | 0.70 (0.61–0.81) | Fixed | <0.00001 | 0 | 0.85 |
| Cut-off values | |||||||
| Median | 9 | 1546 | 0.70 (0.58–0.83) | Fixed | 0.0002 | 12 | 0.34 |
| Others | 8 | 983 | 0.67 (0.57–0.80) | Fixed | <0.0001 | 14 | 0.32 |
| Publication year | |||||||
| Before 2010 | 4 | 427 | 0.58 (0.46–0.74) | Fixed | <0.00001 | 0 | 0.62 |
| After 2010 | 13 | 2,102 | 0.72 (0.63–0.84) | Fixed | 0.02 | 8 | 0.36 |
| Country | |||||||
| China | 7 | 1,400 | 0.76 (0.64–0.91) | Fixed | 0.002 | 0 | 0.49 |
| Japan | 5 | 635 | 0.67 (0.53–0.84) | Fixed | 0.0008 | 0 | 0.83 |
| Australia | 1 | 105 | 0.62 (0.28–1.37) | – | 0.24 | – | – |
| Germany | 2 | 180 | 0.57 (0.42–0.78) | Fixed | 0.0005 | 28 | 0.24 |
| Sweden | 1 | 98 | 0.10 (0.01–0.85) | – | 0.04 | – | – |
| Switzerland | 1 | 111 | 0.73 (0.35–1.49) | – | 0.38 | – | – |
ESCC, esophageal squamous cell carcinoma; EAC, esophageal adenocarcinoma; OS, overall survival; HR, hazard ratio; CI, confidence intervals.