Table 1 Scale for quality assessment
From: Current evidences on XPC polymorphisms and gastric cancer susceptibility: a meta-analysis
Criteria | Score |
|---|---|
Representativeness of cases | Â |
 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 | Â |
 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 | Â |
 Histologically or pathologically confirmed | 2 |
 Diagnosis of gastric cancer by patient medical record | 1 |
 Not described | 0 |
Sample size | Â |
 >1000 | 2 |
 200-1000 | 1 |
 <200 | 0 |
Quality control of genotyping methods | Â |
 Clearly described a different genotyping assay to confirm the data | 1 |
 Not described | 0 |
Hardy-Weinberg equilibrium | Â |
 Hardy-Weinberg equilibrium in controls | 1 |
 Hardy-Weinberg disequilibrium in controls | 0.5 |
 No checking for Hardy-Weinberg disequilibrium | 0 |