Table 3. Results of subgroups analyses of pooled RRs and 95% CIs.
| Subgroups | No. of studies | Heterogeneity | Effect model | Meta-analysis | ||
|---|---|---|---|---|---|---|
| I2(%) | ph | RR (95%CI) | p | |||
| Study design | ||||||
| Cohort | 3 | 0 | 0.39 | Fixed | 1.02 (0.71–1.46) | 0.91 |
| Case-control | 5 | 14.2 | 0.32 | Fixed | 1.48 (1.12–1.96) | <0.01 |
| Cross-sectional | 1 | NA | NA | NA | 1.45 (0.76–2.76) | 0.26 |
| Outcomes | ||||||
| ESCC | 7 | 1.2 | 0.42 | Fixed | 1.21 (0.95–1.53) | 0.13 |
| Mixed | 2 | 36.4 | 0.21 | Fixed | 1.66 (1.08–2.54) | 0.02 |
| Definition of reference group | ||||||
| None lost tooth | 2 | 0 | 0.64 | Fixed | 1.01 (0.70–1.46) | 0.94 |
| No. of lost tooth | 7 | 6.4 | 0.38 | Fixed | 1.46 (1.14–1.89) | <0.01 |
| Effect estimation | ||||||
| Relative risk | 1 | NA | NA | NA | 0.90 (0.48–1.68) | 0.74 |
| Hazard ratio | 2 | 40.3 | 0.20 | Fixed | 1.09 (0.70–1.68) | 0.71 |
| Odds ratio | 6 | 0 | 0.46 | Fixed | 1.47 (1.14–1.91) | <0.01 |
| Adjustment | ||||||
| Smoking | 8 | 0 | 0.46 | Fixed | 1.37 (1.10–1.70) | <0.01 |
| Smoking and alcohol | 7 | 10.4 | 0.35 | Fixed | 1.36 (1.08–1.71) | 0.01 |
No., number; ESCC, esophageal squamous cell carcinoma; RR, relative risk; CI, confidence interval.