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Table 2 Quality assessment of the DOK study design (QUADAS-2)

From: Challenges in diagnostic accuracy studies in primary care: the fecal calprotectin example

Signaling questions

Answer

Risk of bias/applicability

Planned adjustment

Domain 1: Patient selection

   

Risk of bias

 

Low risk

 

Is a consecutive sample of patients enrolled?

Yes

  

Is a case-control design avoided?

Yes

  

Does the study avoid inappropriate exclusions?

Yes

  

Applicability

 

High concern

- Magnitude will be evaluated

Are there concerns that the included patients and setting do not match the topic of our study (patients had symptoms suggestive of inflammatory bowel disease in primary care)?

   

Domain 2: Index test

   

Risk of bias

 

Low Risk

 

Are the index test results interpreted without knowledge of the results of the reference standard?

Yes

  

If a threshold was used, is it pre-specified?

Yes

  

Applicability

 

Low Concern

 

Are there concerns that the index test, its conduct, or interpretation differ from the topic of our study (fecal calprotectin was measured with ELISA)?

   

Domain 3: Reference standard

   

Risk of bias

 

High risk

 

Is the reference standard likely to correctly classify the target condition?

No

 

- Probably not clinically relevant

- Adjustment in analysis [30, 31]

Are the reference standard results interpreted without knowledge of the results of the index test?

Yes

  

Domain 4: Flow and timing

   

Risk of bias

 

High risk

 

Is there an appropriate interval between index test and reference standard?

No

 

- Represents care as usual

- Repeated measurement index test before endoscopy

Do all patients receive a reference standard?

Yes

  

Do all patients receive the same reference standard?

No

 

- Adjustment in analysis [30, 31]