Background
Methods
Study population
Questionnaires
VascuQoL
SF-36
Additional measurements
Psychometric and statistical methods
Content validity
Construct validity
Reliability
Sensitivity and responsiveness
Ethical considerations
Results
Study population and missing data
Demographics and risk factors | |
---|---|
Age (mean + SD) | 70 + 9 y |
Gender (male/female; %) | 57/43 |
Regulary smoking (current or in the last five years), % | 49 |
Previous TIA or stroke, % | 10 |
Diabetes, % | 29 |
Hyperlipidemia, % | 11 |
Angina pectoris/previous myocardial infarction, % | 43 |
Chronic pulmonary disease, % | 13 |
Kidney disease (s-creatinine >150 mmol/l), % | 10 |
Ankle-brachial -index (mean + SD) | 0.70 + 0.18 |
Validity
Content validity
Construct validity
VascuQoL | ||||||
---|---|---|---|---|---|---|
SF-36
|
Total score
|
Pain
|
Activities
|
Symptoms
|
Emotional
|
Social
|
PF | 0.65** | 0.52** | 0.69** | 0.54** | 0.49** | 0.61** |
n = 198 | n = 200 | n = 199 | n = 200 | n = 199 | n = 199 | |
0.83**
|
0.74**
|
0.86**
|
0.72**
|
0.73**
|
0.73**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
RP | 0.53** | 0.47** | 0.51** | 0.48** | 0.42** | 0.48** |
n = 195 | n = 197 | n = 196 | n = 197 | n = 196 | n = 196 | |
0.70**
|
0.62**
|
0.66**
|
0.62**
|
0.65**
|
0.69**
| |
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
| |
BP | 0.67** | 0.62** | 0.62** | 0.57** | 0.58** | 0.49** |
n = 196 | n = 198 | n = 197 | n = 197 | n = 197 | n = 197 | |
0.73**
|
0.78**
|
0.67**
|
0.69**
|
0.66**
|
0.57**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
GH | 0.49** | 0.36** | 0.43** | 0.38** | 0.50** | 0.44** |
n = 196 | n = 198 | n = 197 | n = 198 | n = 197 | n = 197 | |
0.50**
|
0.41**
|
0.47**
|
0.45**
|
0.54**
|
0.40**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
VT | 0.61** | 0.49** | 0.51** | 0.55** | 0.56** | 0.49** |
n = 197 | n = 199 | n = 198 | n = 199 | n = 198 | n = 198 | |
0.65**
|
0.57**
|
0.59**
|
0.60**
|
0.67**
|
0.53**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
SF | 0.34** | 0.21** | 0.19** | 0.29** | 0.41** | 0.43** |
n = 197 | n = 199 | n = 198 | n = 199 | n = 198 | n = 198 | |
0.65**
|
0.51**
|
0.60**
|
0.60*
|
0.66**
|
0.66**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
RE | 0.47** | 0.37** | 0.38** | 0.41** | 0.46** | 0.41** |
n = 196 | n = 198 | n = 197 | n = 198 | n = 197 | n = 197 | |
0.69**
|
0.60**
|
0.63**
|
0.60**
|
0.69**
|
0.72**
| |
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
| |
MH | 0.58** | 0.40** | 0.41** | 0.49** | 0.68** | 0.49** |
n = 197 | n = 199 | n = 198 | n = 199 | n = 198 | n = 198 | |
0.62**
|
0.52**
|
0.52**
|
0.54**
|
0.70**
|
0.58**
| |
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
|
n = 127
| |
PCS | 0.59 | 0.53** | 0.64** | 0.50** | 0.40** | 0.52** |
n = 192 | n = 194 | n = 193 | n = 194 | n = 193 | n = 193 | |
0.79** |
0.74**
|
0.80**
|
0.71**
|
0.68**
|
0.66**
| |
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
| |
MCS | 0.49** | 0.31** | 0.28** | 0.42** | 0.60** | 0.45** |
n = 192 | n = 194 | n = 193 | n = 194 | n = 193 | n = 193 | |
0.57**
|
0.45**
|
0.46**
|
0.49**
|
0.65**
|
0.58**
| |
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
|
n = 126
| |
ABI
| 0.27** | 0.15 | 0.22** | 0.29** | 0.24** | 0.26** |
n = 143 | n = 145 | n = 144 | n = 145 | n = 144 | n = 144 | |
0.09
|
0.17
|
0.10
|
0.12
|
0.01
|
0.11
| |
n = 112
|
n = 112
|
n = 112
|
n = 112
|
n = 112
|
n = 112
|
Multitrait/multi-item scaling tests | |||||
---|---|---|---|---|---|
Item-scale convergent validity
|
Item-scale discriminant validity
|
Scaling fulfillment
| |||
Range of r
|
Criterion 1
|
Range of r
|
Criterion 2
| ||
Scale
|
Item-scale correlations
a
|
% of item scale correlations ≥ 0.40
b
|
Correlation with other scales
c
|
Number of items higher
|
Number of items that meet both criteria 1 and 2
e
|
Activity
| 0.25–0.71 | 88 | 0.04–0.70 | 7/8 | 7/8 |
Pain
| 0.51–0.66 | 100 | 0.38–0.66 | 2/4 | 2/4 |
Emotional
| 0.59–0.76 | 100 | 0.42–0.64 | 5/7 | 5/7 |
Social
| 0.55–0.55 | 100 | 0.48–0.70 | 0/2 | 0/2 |
Symptom
| 0.3–0.55 | 50 | 0.29–0.63 | 0/4 | 0/4 |
Reliability
Scale | Total | Intermittent claudication | Critical limb ischemia | Six months after vascular intervention |
---|---|---|---|---|
Activity
| 0.87 (n = 189) | 0.86 (n = 126) | 0.78 (n = 63) | 0.94 (n = 124) |
Pain
| 0.77 (n = 195) | 0.74 (n = 126) | 0.78 (n = 69) | 0.89 (n = 127) |
Emotional
| 0.88 (n = 192) | 0.85 (n = 127) | 0.89 (n = 65) | 0.94 (n = 127) |
Social
| 0.70 (n = 196) | 0.67 (n = 127) | 0.68 (n = 69) | 0.84 (n = 127) |
Symptom
| 0.64 (n = 194) | 0.56 (n = 127) | 0.61 (n = 60) | 0.73 (n = 126) |
Total
| 0.94 (n = 183) | 0.93 (n = 123) | 0.92 (n = 60) | 0.97 (n = 123) |
Floor- and ceiling effects
Scale | Intermittent claudication (IC), mean ± SD n = 127 | Critical limb ischemia (CLI), mean ± SD n = 71 | p-value | Floor* (IC), % | Ceiling (IC), % | Floor* (CLI), % | Ceiling (CLI), % |
---|---|---|---|---|---|---|---|
Activity
| 3.50 ± 1.12 | 2.44 ± 0.88 | p < 0.001 | 0 | 0 | 4.2 | 0 |
Pain
| 3.69 ± 1.18 | 2.61 ± 1,10 | p < 0.001 | 0.8 | 0 | 8.5 | 0 |
Emotional
| 4.57 ± 1,29 | 3.35 ± 1,48 | p < 0.001 | 0 | 0.8 | 2.8 | 1.4 |
Social
| 4.34 ± 1.60 | 3.17 ± 1,63 | p < 0.001 | 0 | 7.1 | 5.6 | 5.6 |
Symptom
| 4.46 ± 1.09 | 2.97 ± 1,23 | p < 0.001 | 0 | 0 | 5.6 | 0 |
Total
| 4.05 ± 1.03 | 2.87 ± 1.00 | p < 0.001 | 0 | 0 | 1.4 | 0 |