Table 1 Scale for quality assessment
From: Current evidences on XPC polymorphisms and gastric cancer susceptibility: a meta-analysis
| Criteria | Score |
|---|---|
| Representativeness of cases | |
| Selected from cancer registry or multiple cancer center sites | 2 |
| Selected from oncology department or cancer institute | 1 |
| Selected without clearly defined sampling frame or with extensive inclusion/exclusion criteria | 0 |
| Source of controls | |
| Population or community based | 2 |
| Both population-based and hospital-based/healthy volunteers/blood donors | 1.5 |
| Hospital-based controls without gastric cancer | 1 |
| Cancer-free controls without total description | 0.5 |
| Not described | 0 |
| Ascertainment of gastric cancer | |
| Histologically or pathologically confirmed | 2 |
| Diagnosis of gastric cancer by patient medical record | 1 |
| Not described | 0 |
| Sample size | |
| >1000 | 2 |
| 200-1000 | 1 |
| <200 | 0 |
| Quality control of genotyping methods | |
| Clearly described a different genotyping assay to confirm the data | 1 |
| Not described | 0 |
| Hardy-Weinberg equilibrium | |
| Hardy-Weinberg equilibrium in controls | 1 |
| Hardy-Weinberg disequilibrium in controls | 0.5 |
| No checking for Hardy-Weinberg disequilibrium | 0 |