Clinically relevant differences in COPD health status: systematic review and triangulation

Area of Science:

• Pulmonary Medicine
• Clinical Epidemiology
• Health Outcomes Research

Background:

• The minimal clinically important difference (MCID) is crucial for interpreting changes in patient-reported outcomes.
• Chronic obstructive pulmonary disease (COPD) management relies on validated health status tools, but their MCIDs require clear definition.
• Existing MCID values may not accurately reflect clinically meaningful changes in COPD patients.

Purpose of the Study:

• To systematically review and triangulate the MCIDs for various health status measurement tools used in chronic obstructive pulmonary disease (COPD).
• To compare triangulated MCIDs with commonly used values in clinical practice.
• To identify gaps in research regarding MCIDs for COPD deterioration.

Main Methods:

• Systematic literature search across PubMed, EMBASE, and Cochrane Library (PROSPERO #CRD42015023221).
• Extraction and assessment of study details, patient characteristics, and MCID methodologies.
• Triangulation of MCIDs using a weighted mean (2/3 anchor-based, 1/3 distribution-based), adjusted for study size and quality.

Main Results:

• Twenty-one studies were included, presenting MCIDs for 12 COPD health status tools.
• Triangulated MCIDs for improvement were: COPD Assessment Test (CAT) -2.54, Clinical COPD Questionnaire (CCQ) -0.43, and St. George's Respiratory Questionnaire (SGRQ) -7.43.
• Evidence for CAT and CCQ MCIDs was strong; SGRQ MCIDs differed significantly from current clinical values, suggesting potential overestimation of treatment effects.

Conclusions:

• The triangulated MCIDs for CAT and CCQ provide robust estimates for clinically meaningful improvement in COPD.
• Current clinical practice MCIDs for SGRQ and Chronic Respiratory Questionnaire may be underestimated, necessitating updated guidance.
• Further research is needed to establish reliable MCIDs for symptom deterioration in COPD.