Determining The Minimal Important Difference For The St. George’s Respiratory Questionnaire In Patients With Severe COPD.

Welling, J.B.A. (2015) Determining The Minimal Important Difference For The St. George’s Respiratory Questionnaire In Patients With Severe COPD. thesis, Medicine.

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Abstract

Background: The St. George’s Respiratory Questionnaire (SGRQ) is a commonly used validated questionnaire for measuring impaired health and perceived quality of life in patients with chronic obstructive pulmonary disease (COPD). A decrease of 4 units on the SGRQquestionnaire is widely accepted to be a valid threshold value to determine the benefit of an intervention and thus a Minimal Important Difference (MID). However, for patients with severe COPD, the current established MID does not seem to reflect important clinical changes and we presume that the SGRQ MID in this patient-group should be re-evaluated. Objective: The objective of our study is to determine a new MID for the SGRQ in patients with severe COPD. Design: A retrospective analysis of all available 1 and 6 month follow-up data from 7 bronchoschopic lung volume reduction (BLVR) clinical trials in our institution was performed. Anchor-based methods were used to determine the MID for SGRQ. Forced expiratory volume in 1 second (FEV1) [MID: 0.1 liters], 6 minute walking distance (6MWT) [MID: 26 meter] and residual volume (RV) [MID: 0.4 liters] were used as anchors. Measurements: Participants completed the SGRQ at baseline, 1 and 6 months follow-up. In addition participants performed a six-minute walk test, body plethysmography and spirometry measurements. Participants: 117 patients with severe COPD (74 females, mean age 60 years (SD 8.6 years), with a mean FEV1 of 26% predicted (SD 9.3%), a mean RV of 241% predicted (SD: 46.7%), a mean 6MWT of 311 meters (SD 97 meter) and a mean SGRQ total score of 62 units (SD 10.9 units). Results: Pearson correlation coefficients of change in anchor score versus SGRQ change-score were all higher than 0.4. Anchor-based methods identified an average MID at 1 Month of - 8.8 units and an average MID at 6 months of -6.8. Conclusions: We suggest a new MID for the SGRQ in patients with severe COPD at 1 Month of -8.8 and at 6 months of -6.8 units. This new MID estimate could be useful for sample size determination of new studies aimed at treating severe COPD and for interpreting the results from clinical trials in patients with severe COPD.

Item Type:	Thesis (Thesis)
Supervisor name:	Slebos, Dr. Dirk-Jan
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 11:07
Last Modified:	25 Jun 2020 11:07
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/2707

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