Introduction
Methods
Study populations and data collection
Measurement tools
The WHOQOL-BREF
The SGRQ
Statistical analysis
Known-groups validity
Reliability
Floor and ceiling effects
Item convergent validity and item discriminant validity
Correlation analysis
Items related to lung function impairment
Results
Characteristics of subjects
Variable | |
---|---|
Age, mean years (SD) | 70.4 (8.1) |
Lung function, mean % (SD) | |
FEV1
a % predicted | 56.2 (22.0) |
FEV1/FVCb ratio | 56.0 (12.4) |
Education, n (%) | |
Elementary school and below | 142 (67.6) |
Junior and senior high school | 58 (27.6) |
Junior college and above | 10 (4.8) |
Married and lives with spouse, n (%) | 183 (87.1) |
Current smokers, n (%) | 58 (27.6) |
Disease severityc, n (%) | |
Stage 0: at risk | 23 (10.9) |
Stage I: mild | 13 (6.2) |
Stage II: moderate | 74 (35.1) |
Stage III: severe | 84 (39.8) |
Stage IV: very severe | 17 (8.0) |
Scaling properties of the WHOQOL-BREF and the SGRQ
Stage (known groups validity) | (%) at floor | (%) at ceiling | Item convergent validity | Item discriminant validity | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
At risk | I | II | III | IV |
P
a
|
P
b
| α | Success itemsc/total items (%) | Success itemsd/total items (%) | |||||
WHOQOL-BREF | ||||||||||||||
Physical | 15.2 | 13.8 | 12.9 | 12.3 | 9.8 | ** | ** | 0.80 | 1.0 | 0.5 | 6/7 | (85.7) | 25/28 | (89.3) |
Psychological | 15.4 | 11.9 | 12.3 | 12.5 | 10.7 | ** | ** | 0.85 | 1.0 | 1.0 | 6/6 | (100) | 24/24 | (100) |
Social | 15.9 | 11.8 | 13.0 | 12.7 | 11.4 | ** | ** | 0.85 | 2.8 | 5.2 | 4/4 | (100) | 16/16 | (100) |
Environmental | 16.4 | 13.7 | 14.6 | 14.3 | 13.5 | ** | ** | 0.85 | 0 | 1.0 | 9/9 | (100) | 35/36 | (97) |
SGRQ | ||||||||||||||
Symptoms | 40.2 | 47.8 | 51.4 | 53.5 | 61.9 | * | ** | 0.66 | 0 | 1.4 | 6/8 | (75.0) | 23/24 | (95.8) |
Activity | 29.5 | 35.6 | 48.2 | 57.9 | 68.5 | ** | ** | 0.90 | 2.4 | 6.2 | 15/16 | (93.8) | 45/48 | (93.8) |
Impacts | 17.1 | 20.1 | 27.1 | 35.7 | 41.4 | ** | ** | 0.90 | 0 | 5.2 | 19/26 | (73.1) | 71/78 | (91.0) |
Total | 24.6 | 29.4 | 37.4 | 45.4 | 53.0 | ** | ** | 0.94 | 0 | 0 | – | – |
Correlation analysis among HRQL domains and lung functions
WHOQOL-BREF | SGRQ | |||||||
---|---|---|---|---|---|---|---|---|
Physical | Psycho. | Social | Environ. | Symptoms | Activity | Impacts | Total | |
WHOQOL-BREF | ||||||||
Physical | 1 | |||||||
Psychological | 0.71** | 1 | ||||||
Social | 0.53** | 0.73** | 1 | |||||
Environmental | 0.57** | 0.72** | 0.65** | 1 | ||||
SGRQ | ||||||||
Symptoms | −0.39** | −0.40** | −0.42** | −0.29** | 1 | |||
Activity | −0.59** | −0.40** | −0.35** | −0.31** | 0.46** | 1 | ||
Impacts | −0.69** | −0.56** | −0.43** | −0.40** | 0.54** | 0.63** | 1 | |
Total | −0.71** | −0.56** | −0.46** | −0.41** | 0.68** | 0.85** | 0.93** | 1 |
Lung functions | ||||||||
FEV1% predicted | 0.32** | 0.17** | 0.13 | 0.12 | −0.19** | −0.39** | −0.29** | −0.36** |
FEV1/FVC | 0.27** | 0.20** | 0.15* | 0.16* | −0.23** | −0.30** | −0.25** | −0.30** |
Selection of potential predicting items of lung function impairment
Item | Model I FEV1% predicted | Model II FEV1/FVC |
---|---|---|
P
a
|
P
a
| |
WHOQOL-BREF
| ||
Physical | ||
Do you feel that physical pain prevents you from doing what you need to do | 0.0006 | 0.003 |
How is your ability to get aroundb
| <0.0001 | <0.0001 |
Are you satisfied with your ability to perform routine daily activitiesc
| 0.0003 | 0.0001 |
SGRQ
| ||
Symptoms (frequency of respiratory symptom) | ||
Shortness of breath | 0.0075 | 0.0076 |
Activity (activities that cause or are limited by breathlessness) | ||
Walking around the homeb
| <0.0001 | 0.0033 |
Walking outside on the levelb
| <0.0001 | 0.0024 |
Walking up a flight of stairsb
| 0.0009 | 0.0071 |
Walking up hillsb
| 0.0056 | 0.0004 |
I walk more slowly than other people, or I stop for restsb
| <0.0001 | 0.0032 |
Getting washed or dressedc
| <0.0001 | 0.0019 |
Jobs such as housework take a long time, or I have to stop for restsc
| <0.0001 | 0.0001 |
Impacts (aspects concerned with daily life, social functioning and psychological disturbances resulting from airways disease) | ||
How would you describe your chest condition cause you problems | <0.0001 | 0.0053 |
I get breathless when I talk | 0.0014 | 0.0007 |
I have become frail or an invalid because of my chest | <0.0001 | 0.0055 |
I cannot play sports or games | 0.0002 | 0.0045 |
I cannot go out for entertainment or recreation | <0.0001 | 0.0014 |
I cannot go out of the house to do the shopping | 0.0002 | 0.0014 |
The extent to which your chest affects you doing things | <0.0001 | 0.0018 |