1. The Minimal Important Difference for St
The Minimal Important Difference for St. George’s Respiratory Questionnaire in patients with severe COPD
Jorrit Welling, BSc
Department of Pulmonary Diseases
University Medical Centre Groningen

2. Contents: Introduction Research Question & Hypothesis
Materials & Methods
Results
Discussion
Conclusions

3. Introduction: Key Concepts
Chronic Obstructive Pulmonary Disease (COPD)
Bronchoscopic Lung Volume Reduction ( BLVR )
St.George’s Respiratory Questionnaire ( SGRQ )
Minimal Important Difference ( MID )

4. Introduction : COPD Major cause of morbidity and mortality worldwide
“COPD is a progressive lung disease characterized by airflow limitation resulting in premature closure of small airways, air trapping and hyperinflation leading to shortness of breath”
(1) Vestbo J, Hurd SS, Agusti AG, Jones PW, Vogelmeier C, Anzueto A, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Am J Respir Crit Care Med 2013 Feb 15;187(4): 4

5. Introduction: BLVR
Bronchoscopic approach to Lung Volume Reduction Surgery
Valves
Coils 5

6. Introduction: SGRQ & MID
St. George’s Respiratory Questionnaire
Minimal Important Difference
Currently Accepted MID: 4 Units
2. Jones PW, Quirk FH, Baveystock CM. The St George's Respiratory Questionnaire. Respir Med 1991; 85 Suppl B: 25-31; discussion 33-7.
3.Jones PW. St. George's Respiratory Questionnaire: MCID. COPD 2005; 2: 6

7. Research Question & Hypothesis
What is the minimal important difference for SGRQ in patients with severe COPD?
We hypothesize that the currently accepted MID for the SGRQ will not stand and will prove to be larger than 4 SGRQ units.

8. Methods: Study design
Design
Inclusion
Ethics

9. Methods: Measurements & MID Calculation
SGRQ
Spirometry
Body Plethysmography
Exercise Tests
MID calculation:
Anchor-based Methods (FEV1, RV, 6 MWT)
Distribution-based Methods
4. Revicki D, Hays RD, Cella D, Sloan J. Recommended methods for determining responsiveness and minimally important differences for patient-reported outcomes. J Clin Epidemiol 2008; 61:

10. Results: Inclusion
Figure 1: Patient flowchart. SGRQ: St. George’s Respiratory Questionnaire.

11. Results: ( Baseline Characteristics)
Baseline
(n=115)
Δ1 month
From baseline
(n=110)
Δ6 months from
baseline (n=86)
Females/Males
73/42 NA
Age (years)
60±8.8
6MWD (meters)
311±95
38.5±60.7
38.2±68.5
SGRQ Total score (units)
62±10.9
-9.8±13.8
-7.5±15.8
Packyears (years)
36±17
RV (liter)
4.9±1.1
-0.5±0.6
FEV1 (liter)
0.7±0.3
0.1±0.2
Table 1: Patient characteristics at baseline and change at 1 and 6 months follow-up. Data are presented as number or mean ± SD. Δ=change between baseline and follow-up. BMI: body mass index; FEV1: forced expiratory volume in 1 second; 6MWD: 6-minute walk distance; SGRQ: St George’s Respiratory Questionnaire; RV: residual volume; TLC: total lung capacity; NA: not applicable.

12. Results: MID Outcomes SGRQ MID at 1 month at 6 months Anchor: RV -8.7
SGRQ MID
at 1 month
at 6 months
Anchor: RV
-8.7
-6.4
FEV1
-9.2
-7.8
6MWD
-8.5
-6.3
Distribution Based:
-6.9
7.9
Combined:
-8.3
-7.1
Table 2: Minimal Important Differences for SGRQ. Data are presented as SGRQ units or percentage change compared to baseline. MID: Minimal Important Difference; SGRQ: St. George’s Respiratory Questionnaire; RV: residual volume; FEV1: Forced expiratory volume in 1 second; 6MWD: 6-minute walk distance.

13. Discussion: Findings Scope of applicability? Treatment Specific?
Strenghts & Limitations
- Generalisability
Future Prospective
- Evaluation Clinical Trials

14. Conclusions: Retrospective Analysis 7 BLVR Trials
Anchor & Distribution Methods
A SGRQ MID of -8.3/-7.1

15. Acknowledgements Nick H. Ten Hacken Karin Klooster Dirk-Jan Slebos
Jorine E. Hartman
Nick H. Ten Hacken
Karin Klooster
Dirk-Jan Slebos
Groningen Research Institute for Asthma & COPD