Table 2.

Quality Assessment of Cohort and Case-Control Studies Using the Newcastle-Ottawa Scale

Study, Year (Reference)	Selection*				Comparability**	Outcome***
	Representativenessy of Exposed Cohort	Selection of Nonexposed Cohort	Ascertainment of Exposure	Demonstration Outcome Not Present at Study Start	Comparability of Cohorts	Assessment of Outcome	Follow-up Enough for Outcomes to Occur	Adequacy of Follow- up
Phillips et al, 2010 (67)	•	•	•	•	⭘	•	⭘	⭘
Mercer et al, 2012 (65)	•	•	•	⭘	••	•	⭘	⭘
Dreyer et al, 2013 (64)	•	•	•	•	••	•	⭘	⭘
Raaschou et al, 2013**** (66)	•	•	•	•	••	•	•	•
Strangfeld et al, 2013 (41)	•	•	•	•	⭘	•	•	⭘
Raaschou et al, 2014 (68)	•	•	•	•	••	•	•	⭘
Silva-Fernandez et al, 2014 (70)	•	•	•	•	••	•	•	⭘
Axelrad et al, 2015 (63)	•	•	•	•	••	•	•	⭘
Scott et al, 2015 (69)	•	•	⭘	•	••	⭘	⭘	•
Scott et al, 2015 (69)	•	•	⭘	•	••	⭘	⭘	•

• = study fulfilled the listed criteria. ⭘ = study did not fulfill the listed criteria.

^*Representativeness of the exposed cohort: • given if representative of the average patient with cancer and an inflammatory condition in the community. ⭘ given if selected from a group of volunteers or derivation of the cohort is not described.

^*Selection of the non-exposed cohort: • given if drawn from the same community as the exposed cohort. ⭘ given if selected from a group of volunteers or derivation of the cohort is not described.

^*Ascertainment of exposure: • given if obtained by a secure record or structured interview. ⭘ given if no description is given or self-report.

^*Demonstration that outcome was not present at start of study: • given if demonstrated. ⭘ given if not demonstrated.

^**Comparability of cohorts on the basis of design or analysis: • given if study controlled for factor related to the risk of cancer recurrence. •• given if study controlled for an additional factor.

^***Assessment of outcome: • given if obtained by independent blind assessment or record linkage. ⭘ given if obtained from self-report or not described.

^***Was follow-up long enough for outcomes to occur: • given if follow-up was long enough for outcome to occur (36 months of anti-TNF exposure). ⭘ given if follow-up was not long enough.

^***Adequacy of follow-up of cohorts: • given if complete follow-up is provided or ≥ 90% of follow-up is provided. ⭘ given if follow-up rate was < 90% or no description is provided.

^****For case-control study:

Selection: • given as the cancer diagnosis was obtained from record linkage, cases were obtained from a record (series of cases), controlled were obtained from the same record linkage and controls were not exposed to anti-TNF therapy.

Comparability: •• given as cases and controls matched based on age at cancer diagnosis, sex, year of cancer diagnosis, county of residence and cancer stage.

Exposure: • given as the ascertainment was from a secure record and the same for cases and controls. Follow-up was described for both groups.