Table 1 Risk of bias tools included
From: Inter-rater reliability of risk of bias tools for non-randomized studies
Tool (study design) | Tool content and judgment criteria | Reporting of results |
|---|---|---|
Frequency studies | ||
Gyorkos et al. (cohort) [7] | Checklist, 4 categories • Selection of participants • Intervention/exposure • Outcome • Follow-up | Overall assessment into low risk of bias (few minor flaws and no major flaws), intermediate risk of bias (some minor flaws and no major flaws), high risk of bias (≥ 1 major flaw). No explicit guidance on the weight of individual items |
Gyorkos et al. (cross-sectional) [7] | Checklist, 3 categories • Selection of participants • Intervention/exposure • Outcome | |
Loney et al. (cohort & cross-sectional) [6] | Scale, 8 questions • Selection of participants • Statistical analyses • Validity of study methods • Applicability of results | Overall assessment into low risk of bias (6–8 points), intermediate risk of bias (3–5 points), high risk of bias (0–2 points). No explicit guidance on the weight of individual items |
AAN ROB tool (population screening scheme) [5] | AAN tool, 4 classes • Selection of participants • Assessment of outcomes | Overall assessment into low risk of bias (class 1), intermediate risk of bias (class 2), high risk of bias (class 3) depending on criteria for each class. No weighting necessary. Class 4 articles (highest risk of bias) not considered in our study, as not used for published AAN guidelines |
Exposure studies | ||
SIGN50 (cohort) [9] | Checklist, 14 questions • Research question • Selection of participants • Assessment of outcomes • Confounding • Statistical analyses | Overall assessment into low risk of bias (+ +), intermediate risk of bias ( +), high risk of bias ( −). No explicit guidance on the weight of individual items |
SIGN50 (case–control) [9] | Checklist, 11 questions • Research question • Selection of participants • Assessment of outcomes • Confounding • Statistical analyses | |
Newcastle–Ottawa scale (cohort) [8] | Scale, 8 questions • Selection of participants • Comparability of groups • Exposure | Each selected response may or may not be associated with a star. Overall assessment into low risk of bias (≥ 7 stars), intermediate risk of bias (4–6 stars), high risk of bias (≤ 3 stars). No explicit guidance on the weight of individual items |
Newcastle–Ottawa scale (case–control) [8] | Scale, 8 questions • Selection of participants • Comparability of groups • Exposure | |
AAN ROB (prognostic accuracy scheme) [5] | AAN scheme, 4 classes • Confounding • Assessment of outcomes | Overall assessment into low risk of bias (class 1), intermediate risk of bias (class 2), high risk of bias (class 3) depending on criteria for each class. No weighting necessary |