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Table 1 Judging whether a change in patient management is likely to improve patient health outcomes

From: Using patient management as a surrogate for patient health outcomes in diagnostic test evaluation

Test claim

Improved health outcomes

Conclusion

Example

 

Assumption 1

Assumption 2

  
 

Test accuracy

Supportive evidence

Impact of changed management on health outcomes

Supportive evidence

  

Adds effective treatment by detecting more cases

(where new test pos, existing tests neg)

New test is more sensitive than existing tests

(more TP cases)

Comparative accuracy study

Benefits for TP

Absolute treatment benefits outweigh harms:

i) risk of disease events is clinically important, and

i) study measuring prognosis in test-stratified population

Judgement

Evidence supports potential benefits of treatment for TP, and these benefits outweigh harms for FP

Or

Require RCT

Breast MRI added to conventional imaging

   

ii) relative treatment effects for TP detected by existing tests also apply to additional TP detected by new test

ii) RCT measuring treatment effectiveness for disease subgroups

  
   

Harms for FP

iii) harms of unnecessary treatment are acceptable

iii) study measuring risk of treatment adverse events

  

Avoids unnecessary treatment or further tests by excluding more non-cases

(where new test neg, existing tests pos)

New test is more specific than existing tests

(fewer FP cases)

Comparative accuracy study

Benefits for TN

i) treatment or further tests carry a risk of adverse events

i) study measuring risk of treatment adverse events

Judgement

Evidence supports benefits of avoiding treatment or further tests for TN outweigh potential harms for FN cases

Or

Require RCT

POC prothrombin time versus clinical judgement

   

Harms for FN

ii) harms of omitting/delaying treatment in FN cases are acceptable

ii) study measuring prognosis in test negative patients not receiving treatment

  
  1. Abbreviations: pos = positive, neg = negative, TP = true positive, FP = false positive, TN = true negative, FN = false negative, RCT = randomised controlled trial, MRI = magnetic resonance imaging, POC = Point-of-care