Using Spirometry to Appropriately Diagnose COPD

Article for Discussion

van Dijk W, Tan W, Li P, et al. Clinical relevance of fixed ratio vs lower limit of normal of FEV1/FVC in COPD: patient-reported outcomes from the CanCOLD cohort. Ann Fam Med. 2015;13(1):41–48.

Discussion Tips

This article analyzes data from the cross-sectional phase of a population-based cohort study in Canada to examine the clinical relevance of different combinations of spirometry criteria for diagnosing chronic obstructive pulmonary disease (COPD). The study considers the impact of misdiagnosis of COPD while exploring diagnostic criteria and the relationship to clinically relevant disease.

Discussion Questions

• What question is asked by this study and why does it matter?

• How does this study advance beyond previous research and clinical practice on this topic?

• How strong is the study design for answering the question?

• What other modifying factors may be important to consider?

• To what degree can the findings be accounted for by:

  1. How patients were selected, excluded, or lost to follow-up?

  2. How the main variables were measured—both the diagnostic criteria and the outcome variables?

  3. Confounding (false attribution of causality because 2 variables discovered to be associated actually are associated with a 3rd factor)?

  4. Chance?

  5. How the findings were interpreted?

• What are the main study findings?

• How comparable is the study sample to similar patients in your practice? What is your judgment about the transportability of the findings?

• What contextual factors are important for interpreting the findings?

• How might this study change your practice? Policy? Education? Research?

• Who the constituencies are for the findings, and how they might be engaged in interpreting or using the findings?

• What are the next steps in interpreting or applying the findings?

• What might be the financial impact of this study’s results?

• What researchable questions remain?