Methodology Checklist 4: Case-control 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 case-control 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: Reason for rejection: 1. Paper not relevant to key question □   2. Other reason □ (please specify):	
Section 1:  Internal validity	
In an well conducted case control 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 cases and controls are taken from comparable populations.	Yes  
Can’t say 	No 
	
1.3	The same exclusion criteria are used for both cases and controls.	Yes  
Can’t say 	No 
	
1.4	What percentage of each group (cases and controls) participated in the study?	Cases:
Controls:	
1.5	Comparison is made between participants and non-participants to establish their similarities or differences.	Yes  
Can’t say 	No 
	
1.6	Cases are clearly defined and differentiated from controls.	Yes  
Can’t say 	No 
	
1.7	It is clearly established that controls are non-cases.	Yes  
Can’t say 	No 
	
ASSESSMENT	
1.8	Measures will have been taken to prevent knowledge of primary exposure influencing case ascertainment.
	Yes  
Can’t say 	No 
Does not apply 	
1.9	Exposure status is measured in a standard, valid and reliable way.	Yes  
Can’t say 	No 
	
CONFOUNDING	
1.10	The main potential confounders are identified and taken into account in the design and analysis.	Yes  
Can’t say 	No 
	
STATISTICAL ANALYSIS	
1.11	Confidence intervals are 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 by 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..