Study | Selectiona | Comparabilityb | Outcomec | Total (quality) scored | Quality | Ref |
|---|
CLCGP | 4 | 2 | 2 | 8 | High | [26] |
Molina-Vila | 4 | 1 | 2 | 7 | High | [27] |
Bria E | 3 | 2 | 3 | 8 | High | [42] |
Canale M | 2 | 2 | 3 | 7 | High | [44] |
Labbé C | 3 | 2 | 3 | 8 | High | [33] |
VanderLaan | 3 | 1 | 2 | 6 | Medium | [28] |
Aisner | 3 | 2 | 3 | 8 | High | [25] |
Tsui DWY | 3 | 2 | 2 | 7 | High | [40] |
Helena A.Yu | 3 | 2 | 3 | 8 | High | [48] |
Kim Y | 4 | 2 | 3 | 9 | High | [43] |
Rachiglio AM | 4 | 2 | 2 | 8 | High | [34] |
Kron A | 4 | 2 | 1 | 7 | High | [45] |
Yu Y | 3 | 2 | 3 | 8 | High | [46] |
Christopoulos P | 3 | 2 | 3 | 8 | High | [41] |
Song P | 4 | 2 | 3 | 9 | High | [47] |
- Selectiona, graded based on 4 items as follows: firstly, representativeness of the exposed cohort (0 points, selected group of users, or no description of the derivation of the cohort;1 point, truly or somewhat representative of the average level in the community); secondly, selection of the non-exposed cohort (0 point, drawn from a different source or no description of the derivation of the non-exposed cohort; 1 point, drawn from the same community as the exposed cohort); thirdly, ascertainment of exposure (0 point, written self-report or no description; 1 point, secure record or structured interview); fourthly, demonstration that outcome of interest was not present at the start of the study (0 point, no;1 point, yes). Comparabilityb, graded as 0–2 points (0 point, study controls without the most important factor or any additional factor; 1 point, study controls for the most important factor or any additional factor; 0 points, study controls for the most important factor and any additional factor). Outcomec, graded based on 3 items: firstly, assessment of outcome (1point, independent blind assessment or record linkage; 0 point, self-report or no description); secondly, was follow-up long enough for outcomes to occur? (1 point, yes; 0 point, no); thirdly, adequacy of follow-up of cohorts (1point, complete follow-up or subjects lost to follow-up unlikely to introduce bias; 0 point, follow-up rate < 80% and no description of those lost, or no statement)
