Table 1.

Risk of Bias (ROB) Items. (b) Adapted from Newcastle-Ottawa Scale (NOS)s for Case-Control Study

Risk of bias items
SELECTION
1. Is the Case Definition Adequate?
(a) yes, low risk of bias (e.g., eligibility criteria/ operational definition)
(b) yes, high risk of bias (e.g., not stated in part (a))
(c) no description, unclear risk of bias
2. Representativeness of the Cases
(a) yes, low risk of bias (e.g., consecutive representative series of cases)
(b) yes, high risk of bias (e.g., not satisfying requirements in part (a), or not stated)
(c) no description, unclear risk of bias
3. Selection of Controls
a) yes, low risk of bias (e.g., community controls)
b) yes, high risk of bias (e.g., hospital controls)
c) no description, unclear risk of bias
4. Definition of Controls
a) yes, low risk of bias (e.g., no history of CCA)
b) yes, high risk of bias (e.g., no mention of history of CCA)
c) no description of source, unclear risk of bias
COMPARABILITY
1. Comparability of cases and controls on the basis of the design or analysis
a) yes, low risk of bias (e.g., matching consideration by age, multiple analysis with age adjusted)
b) yes, high risk of bias (e.g., not stated in part (a))
c) no description of source, unclear risk of bias
EXPOSURE
1. Ascertainment of exposure
a) yes, low risk of bias (secure record e.g., surgical records; structured interview where blind to case/control status)
b) yes, high risk of bias (e.g., interviewer not blinded to case/control status; written self report or medical record only)
c) no description of source, unclear risk of bias
2. Same method of ascertainment for cases and controls
a) yes, low risk of bias (e.g., use of a structured questionnaire)
b) yes, high risk of bias (e.g., not stated in part (a))
c) no description of source, unclear risk of bias
3. Non-Response rate
a) yes, low risk of bias (e.g., same rate for both groups)
b) yes, high risk of bias (e.g., non-respondents described; rate different and no designation)
c) no description of source, unclear risk of bias