NICE quality appraisal checklist29 adapted from Griffiths et al3
| Criteria | Weak | Moderate | Strong | |||
| Section 1: Population | ||||||
| 1.1 Is the source population or source area well described? | 15% | (8) | 42% | (22) | 42% | (22) |
| 1.2 Is the eligible population or area representative of the source population or area? | 19% | (10) | 44% | (23) | 37% | (19) |
| 1.3 Do the selected participants or areas represent the eligible population or area? | 8% | (4) | 50% | (26) | 42% | (22) |
| Section 2: Confounding factors | ||||||
| 2.1 How well were likely confounding factors identified and controlled? | 38% | (20) | 19% | (10) | 42% | (22) |
| Section 3: Measures | ||||||
| 3.1 Were the main measures and procedures reliable? | 2% | (1) | 85% | (44) | 13% | (7) |
| 3.2 Were the outcome measurements complete? | 0% | (0) | 50% | (26) | 50% | (26) |
| Section 4: Analyses | ||||||
| 4.0 Study design and analyses | 92% | (48) | 8% | (4) | 0% | (0) |
| 4.1 Was the study sufficiently powered to detect an effect (if one exists)? | 8% | (4) | 23% | (12) | 69% | (36) |
| 4.2 Were the analytical methods appropriate? | 37% | (19) | 46% | (24) | 17% | (9) |
| 4.3 Was the precision of association given or calculable? Is association meaningful? | 8% | (4) | 19% | (10) | 73% | (38) |
| Section 5: Summary | ||||||
| 5.1 Are the study results internally valid (ie, unbiased)? | 27% | (14) | 40% | (21) | 33% | (17) |
| 5.2 Are the findings generalisable to the source population (ie, externally valid)? | 15% | (8) | 37% | (19) | 48% | (25) |
NICE, National Institute for Health and Care Excellence.