Domains	Signalling items	Risk of bias ratings
1. Study participation	(a) Adequate participation in study by eligible individuals	Relationship between PF and outcome ‐
	(b) Description of target population	High: very likely to be different for participants and eligible non‐participants
	(c) Description of baseline study sample	Moderate: may be different for participants and eligible non‐participants
	(d) Adequate description of recruitment process	Low: unlikely to be different for participants and eligible non‐participants
	(e) Adequate description of period and place of recruitment
	(f) Adequate description of inclusion/exclusion criteria
2. Study attrition	(a) Adequate response rate for study participants	Relationship between PF and outcome ‐
	(b) Description of process for collecting information on participants who dropped out	High: very likely to be different for completing and non‐completing participants
	(c) Reasons for loss to follow‐up provided	Moderate: may be different for completing and non‐completing participants
	(d) Adequate description of participants lost to follow‐up	Low: unlikely be different for completing and non‐completing participants
	(e) No important differences between participants who completed the study and those who dropped out
3. Prognostic factor (PF) measurement	(a) Clear definition of PF provided	Measurement of PF ‐
	(b) Method of PF measurement is adequately valid and reliable	High: very likely to be different for different levels of outcome of interest
	(c) Continuous variables are reported	Moderate: may be different for different levels of outcome of interest
	(d) Method and setting of measurement of PF is identical for all participants	Low: unlikely to be different for different levels of outcome of interest
	(e) Adequate proportion of study sample has complete data for PF
	(f) Appropriate methods of imputation used for missing PF data
4. Outcome measurement	(a) Clear definition of outcome provided	High: outcome measurement very likely to be different related to baseline level of PF
	(b) Method of outcome measurement is adequately valid and reliable	Moderate: outcome measurement may be different related to baseline level of PF
	(c) Method and setting of outcome measurement is identical for all participants	Low: outcome measurement unlikely to be different related to baseline level of PF
5. Adjustment for other prognostic factors	(a) All other important PFs measured	Observed effect of PF on outcome ‐
	(b) Clear definitions of important PFs measured provided	High: very likely to be distorted by another factor related to PF and outcome
	(c) Measurement of all important PFs adequately valid and reliable	Moderate: may be distorted by another factor related to PF and outcome
	(d) Measurement and setting of PF measurement identical for all participants	Low: unlikely to be distorted by another factor related to PF and outcome
	(e) Appropriate methods are used to deal with missing values of PFs
	(f) Important PFs accounted for in study design
	(g) Important PFs accounted for in analysis
6. Statistical analysis and reporting	(a) Sufficient presentation of data to assess adequacy of analytic strategy	Reported results ‐
	(b) Strategy for model building appropriate and based on a conceptual framework or model	High: very likely to be spurious or biased related to analysis or reporting
	(c) Selected statistical model adequate for design of study	Moderate: may be spurious or biased related to analysis or reporting
	(d) No selective reporting of results	Low: unlikely to be spurious or biased related to analysis or reporting