S I G N	Methodology Checklist 3: Cohort studies	
Study identification  (Include author, title, year of publication, journal title, pages)
	
Guideline topic:  	Key Question No:	Reviewer:	
Before completing this checklist, consider:
1.	Is the paper really a cohort study? If in doubt, check the study design algorithm available from SIGN and make sure you have the correct checklist.
2.	Is the paper relevant to key question? Analyse using PICO (Patient or Population Intervention Comparison Outcome). IF NO REJECT (give reason below). IF YES complete the checklist..	
Reason for rejection: 1. Paper not relevant to key question □   2. Other reason □  (please specify):
Please note that a retrospective study (ie a database or chart study) cannot be rated higher than +.	
Section 1:  Internal validity	
In a well conducted cohort study:	Does this study do it?	
1.1	The study addresses an appropriate and clearly focused question.	Yes  □
Can’t say □	No □
	
Selection of subjects	
1.2	The two groups being studied are selected from source populations that are comparable in all respects other than the factor under investigation.	Yes  □
Can’t say □	No □
Does not apply □	
1.3	The study indicates how many of the people asked to take part did so, in each of the groups being studied.
	Yes  □
	No □
Does not apply □	
1.4	The likelihood that some eligible subjects might have the outcome at the time of enrolment is assessed and taken into account in the analysis.	Yes  □
Can’t say □	No □
Does not apply □	
1.5	What percentage of individuals or clusters recruited into each arm of the study dropped out before the study was completed.		
1.6	Comparison is made between full participants and those lost to follow up, by exposure status.	Yes  □
Can’t say □	No □
Does not apply □	

ASSESSMENT	
1.7	The outcomes are clearly defined.	Yes  □
Can’t say □	No □
	
1.8	The assessment of outcome is made blind to exposure status. If the study is retrospective this may not be applicable.	Yes  □
Can’t say □	No □
Does not apply □	
1.9	Where blinding was not possible, there is some recognition that knowledge of exposure status could have influenced the assessment of outcome.	Yes  □
Can’t say □	No □
□	
1.10	The method of assessment of exposure is reliable.	Yes  □
Can’t say □	No □
	
1.11	Evidence from other sources is used to demonstrate that the method of outcome assessment is valid and reliable.	Yes  □
Can’t say □	No □
Does not apply□	
1.12	Exposure level or prognostic factor is assessed more than once.	Yes  □
Can’t say □	No □
Does not apply □	
CONFOUNDING	
1.13	The main potential confounders are identified and taken into account in the design and analysis.	Yes  □
Can’t say □	No □
	
STATISTICAL ANALYSIS	
1.14	Have confidence intervals been provided?	Yes  □	No □	
Section 2:  OVERALL ASSESSMENT OF THE STUDY	
2.1	How well was the study done to minimise the risk of bias or confounding?
	High quality (++) □
Acceptable (+) □
Unacceptable – reject 0 	
2.2	Taking into account clinical considerations, your evaluation of the methodology used, and the statistical power of the study, do you think there is clear evidence of an association between exposure and outcome?	Yes  
Can’t say 	No 
	
2.3	Are the results of this study directly applicable to the patient group targeted in this guideline?	Yes  □	No □	
2.4	Notes. Summarise the authors conclusions. Add any comments on your own assessment of the study, and the extent to which it answers your question and mention any areas of uncertainty raised above.