Table 4.

Risk of bias assessment of the observational studies^a

Cohort study	Representativeness of exposed cohort	Selection of unexposed cohort	Ascertainment of exposure	Demonstration that outcome not present at study start	Comparability of cohorts on age	Comparability of cohorts on other factors	Assessment of outcome	Adequate length of follow-up	Adequacy of follow-up cohorts	Overall scoreb
Herbert et al. [21]	✓ Truly representative	✓ Same community	✓ Secure record	✓ Yes	✓ Yes	No	✓ Record linkage	✓ Yes (3 years)	✓ All subjects followed	8
Rebolj et al. [22]	✗
Case control study	Adequate case definition	Representative cases	Selection of controls	Definition of controls	Comparability of controls on age	Comparability of controls on other factors	Ascertainment of exposure	Method of ascertainment	Non-response rate	Overall scoreb
Andrae et al. [24]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	✓ No history of disease	✓ Yes	No	✓ Secure record	✓ Same for both groups	✓ Same for both groups	8
Aristizabal et al.[15]	✓ Independently validated	✓ Representative cases	✓ Community and hospital controls	Not stated	✓ Yes	✓ Neighborhood	✓ Secure record and non-blinded interview	✓ Same for both groups	Not stated	7
Berrino et al.[16]	✓ Independently validated	✓ Consecutive cases	Hospital controls	✓ No history of disease	✓ Yes	No	✓ Secure record	✓ Same for both groups	✓ Same for both groups	7
Clarke and Anderson [17]	✓ Independently validated	✓ Representative cases	✓ Community controls	Not stated	✓ Yes	✓ Neighborhood and type of dwelling	✓ Secure record and non-blinded interview	✓ Same for both groups	Non-respondents described	7
Decker et al.[25]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	✓ No history of disease	✓	✓ Area of residence	✓ Secure record	✓ Same for both groups	✓ Same for both groups	9
Hernández-Avila et al.[26]	✓ Independently validated	✓ Representative cases	✓ Community controls	Not stated	✓Yes	✓ Age of sexual debut, # normal births, # sex partners, SES	Non-blinded interview	✓ Same for both groups	Rate different/no designation	6
Herrero et al.[18]	✓ Independently validated	Not stated	Hospital controls	✓ No history of disease	No	No	Non-blinded interview	✓ Same for both groups	✓ Same for both groups	4
Hoffman et al.[27]	✓ Independently validated	Not stated	Hospital controls	✓ No history of disease	✓ Yes	✓ Race, area of residence, hospital	Interview	✓ Same for both groups	✓ Same for both groups	6
Jiménez-Pérez and Thomas [28]	✓ Independently validated	✓ Consecutive cases	Hospital controls	✓ No history of disease	✓ Yes	✓ Area of residence	Non-blinded interview	✓ Same for both groups	✓ Same for both groups	7
Kasinpila et al.[38]	✓ Independently validated	✓ Consecutive cases	Hospital controls	✓ No history of disease	✓ Yes	✓ Significant risk factors	Non-blinded interview	✓ Same for both groups	✓ Same for both groups	7
La Vecchia et al.[19]	✓ Independently validated	✓ Representative cases	Hospital controls	✓ No history of disease	✓ Yes	No	Interview	✓ Same for both groups	✓ Same for both groups	6
Makino et al.[29]	✓ Independently validated	Potential for selection bias	✓ Community controls	✓ No history of disease	✓ Yes	✓ Area of residence	Self-report	✓ Same for both groups	✓ Same for both groups	7
Miller et al.[31]	✓ Independently validated	Potential for selection bias	Hospital controls	✓ No history of disease	✓ Yes	✓ Length of membership in health program, race/ethnicity	✓ Secure record	✓ Same for both groups	✓ Same for both groups	7
Nieminen et al.[23]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	Not stated	✓ Yes	✓ Socio-demographics, parity, smoking	Self-report	✓ Same for both groups	Rate different/no designation	6
Sasieni et al.[32-35]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	Not stated	✓ Yes	✓ Area of residence	✓ Secure record	✓ Same for both groups	✓ Same for both groups	8
Talbott et al.[30]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	Not stated	✓ Yes	✓ Sex, race, street or neighborhood	Non-blinded interview	✓ Same for both groups	✓ Same for both groups	7
Yang et al.[36]	Record linkage	Not stated	Hospital controls	✓ No history of disease	✓ Yes	No	✓ Secure record	✓ Same for both groups	✓ Same for both groups	5
Zappa et al.[37]	✓ Independently validated	✓ Consecutive cases	✓ Community controls	Not stated	✓ Yes	No	✓ Secure record	✓ Same for both groups	✓ Same for both groups	7

^aRisk of bias was assessed using the Newcastle-Ottawa Scale [39]; ^b A higher overall score (maximum = 9) corresponds to a lower risk of bias.

✓ The study met this assessment criterion. ✗ This study could not be assessed with this scale. There was no unexposed cohort; both cohorts received screening. The two groups differed in terms of their age at exposure.