Do clinical practice guidelines consider evidence about diagnostic test consequences on patient-relevant outcomes? A critical document analysis

Rationale, aims and objectives: Supporting evidence for diagnostic test recommendations in clinical practice guidelines (CPGs) should not only include diagnostic accuracy, but also downstream consequences of the test result on patient-relevant outcomes. The aim of this study is to assess the extent to which evidence-based CPGs about diagnostic tests cover all relevant test-treatment pathway components. Methods: We performed a systematic document analysis and quality assessment of publicly accessible CPGs about three common diagnostic tests: C-reactive protein, colonoscopy and fractional exhaled nitric oxide. Evaluation of the impact of the full test-treatment pathway (diagnostic accuracy, burden of the test, natural course of target condition, treatment effectiveness, and link between test result and administration of treatment) on patient relevant outcomes was considered best practice for developing medical test recommendations. Results: We retrieved 15 recommendations in 15 CPGs. The methodological quality of the CPGs varied from poor to excellent. Ten recommendations considered diagnostic accuracy. Four of these were funded on a systematic review and rating of the certainty in the evidence. None of the CPGs evaluated all steps of the test-treatment pathway. Burden of the test was considered in three CPGs, but without systematically reviewing the evidence. Natural course was considered in two CPGs, without a systematic review of the evidence. In three recommendations, treatment effectiveness was considered, supported with a systematic review and rating of the certainty in the evidence in one CPG. The link between test result and treatment administration was not considered in any CPG. Conclusions: The included CPGs hardly seem to consider evidence about test consequences on patient-relevant outcomes. This might be explained by reporting issues and challenging methodology. Future research is needed to investigate how to facilitate guideline developers in explicit reliable consideration of all steps of a test-treatment pathway when developing diagnostic test recommendations.