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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
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
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