The CAMPHOR and SF-36 patient reported outcome measures are compared with regards to their psychometric quality for Pulmonary Hypertension (PH) patients.

1. Twiss J, Ben-L’amri M, McKenna SP
February 2012
Galen Research Ltd.
Comparison of the CAMPHOR
and SF-36 for Pulmonary
Hypertension (PH) patients

2. Introduction
• CAMPHOR and SF-36 both widely used measures in PH
• CAMPHOR is the only disease-specific measure for PH
• CAMPHOR has been shown to be unidimensional,
reliable, valid and responsive in this patient group
(McKenna, 2006; Meads, 2008)
Aims of study
To compare psychometric quality of the CAMPHOR and
SF-36

3. Methodology
• Sample: 65 Australian PH patients
• CAMPHOR and SF-36 data available at two
time points
• Measures were assessed for:
– Floor (% min) and Ceiling (% max) effects
[High % = lack of sensitivity]
– Internal consistency (required minimum=0.70)
– Test-retest reliability (required minimum=0.85)
– Construct validity by WHO classification

4. Results – Demographics (n=65)
Gender
Male (%) 14 (21.5)
Female (%) 51 (78.5)
Age
Mean (SD) 57.2 (14.5)
Range 20.1-87.5
WHO Classification
1 (%) 3 (4.6)
2 (%) 18 (27.7)
3 (%) 40 (61.5)
4 (%) 4 (6.2)

5. Floor and Ceiling effects – SF-36 Time 1
0%
5%
10%
15%
20%
25%
30%
PF RP BP GH VT SF RE MH
Floor effect Ceiling effect

6. Floor and Ceiling effects – CAMPHOR Time 1
0%
5%
10%
15%
20%
25%
30%
Symptoms Activity Limitations QoL
Floor effect Ceiling effect

7. Interpretation of findings
• Three of the eight SF-36 domains had high
ceiling effects
• This indicates that domains lack sensitivity in
this patient group
• Low levels of floor and ceiling effects found for
the CAMPHOR
• CAMPHOR scales were well matched to
severity level of the patients

8. Internal consistency – interpretation of
findings
• All domains and scales showed adequate
internal consistency
• This indicates that the items were sufficiently
inter-related
• However, this is not a sufficient test of
reproducibility – crucial for a measure
intended to detect change

9. Test-retest reliability
Measure Item Test-retest % explained
variance (r2)
SF-36 Physical Functioning .93 86
General Health Perceptions .94 88
Role-Physical .81 66
Bodily Pain .72 52
Vitality .78 61
Social Functioning .76 58
Role-emotional .70 49
Mental Health .75 56
CAMPHOR Symptoms .86 74
Activity Limitations .87 76
Quality of Life .94 88
Unacceptable
level of
reliability

10. Interpreting test-retest data: confidence
intervals for the SF-36 and CAMPHOR
Test-retest Time 1 mean SEM* Corresponding CI**
SF-36 Physical Functioning .93 35.3 5.79 29.5 - 41.1
Role-Physical .81 41.9 12.16 29.7 - 54.1
Bodily Pain .72 53.4 13.28 40.1 - 66.7
General Health .94 30.3 4.85 25.5 - 35.1
Vitality .78 38.2 11.16 27.0 - 49.4
Social Functioning .76 62.1 15.24 46.9 - 77.3
Role-emotional .70 67.9 17.09 50.8 - 85.0
Mental Health .75 67.4 8.95 58.5 - 76.4
CAMPHOR Symptoms .86 13.0 2.24 10.8 - 15.2
Activities .87 9.9 2.13 7.8 - 12.0
QoL .94 10.4 1.59 8.8 - 12.0
*SEM = Standard error of measurement; ** Corresponding confidence interval

11. Interpreting test-retest data– SF-36
• Six of eight domains below 0.85
• Large confidence intervals observed
• This indicates the domains have high levels of
random measurement error
• Such high levels of random measurement
error make the measure unsuitable for clinical
trials

12. Interpreting test-retest data–CAMPHOR
• The CAMPHOR scales had excellent test-retest
reliability
• Narrow confidence intervals
• Low levels of random measurement error
• Changes on CAMPHOR scales are more likely
to be accurate
• CAMPHOR more likely to detect real changes
associated with effective interventions

13. Known-Groups validity – SF-36
PF
Mean
(SD)
RP
Mean
(SD)
BP
Mean
(SD)
GH
Mean
(SD)
VT
Mean
(SD)
SF
Mean
(SD)
RE
Mean
(SD)
MH
Mean
(SD)
TIME 1
WHO
Classification
1 & 2 49.5
(21.6)
61.3
(26.9)
60.1
(25.9)
38.9
(18.5)
48.2
(20.5)
75.0
(27.4)
82.9
(19.3)
72.1
(17.1)
3 & 4 27.9
(18.4)
31.4
(22.5)
49.9
(24.3)
25.7
(19.1)
33.0
(24.0)
55.3
(31.1)
59.8
(33.5)
64.9
(18.0)
p .000 .000 .360 .009 .015 .014 .010 .165
TIME 2
WHO
Classification
1 & 2 48.5
(23.8)
59.4
(20.7)
61.7
(25.8)
38.3
(20.7)
47.9
(20.9)
72.6
(24.2)
76.2
(23.3)
73.8
(16.7)
3 & 4 28.3
(17.2)
34.2
(27.6)
50.6
(26.4)
26.4
(20.8)
31.4
(19.4)
54.5
(30.3)
63.8
(30.0)
68.0
(19.1)
p .001 .001 .158 .034 .005 .027 .123 .167

14. Known-Groups validity – CAMPHOR
Symptoms Activity Limitations QoL
TIME 1
WHO Classification
1 & 2 10.4 (5.3) 7.2 (5.7) 7.3 (6.1)
3 & 4 14.3 (5.9) 11.2 (5.7) 11.9 (6.2)
p 0.012 0.011 0.007
TIME 2
WHO Classification
1 & 2 10.1 (5.3) 7.7 (6.2) 7.8 (5.8)
3 & 4 13.6 (6.0) 12.3 (5.5) 12.2 (6.1)
p 0.031 0.003 0.006

15. Interpreting known-groups validity
findings – SF-36
• Bodily Pain, Role-Emotional and Mental
Health domains did not distinguish between
severity groups
• A measure used for PH patients should be able
to distinguish between the relatively large
differences between WHO classes
• Raises doubts about ability of SF-36 to
distinguish between interventions

16. Interpreting known-groups validity data –
CAMPHOR
• All scales were able to distinguish between
WHO classes
• The CAMPHOR is sensitive to clinically
relevant information

17. Previous research showing MID values
Measure Scale Score range MID value
SF-36 Physical functioning 0-100 13
Role-physical 0-100 25
Social functioning 0-100 21
Vitality 0-100 15
CAMPHOR Symptoms 0-25 2
Activity limitations 0-30 2
QoL 0-25 2
Utility 0-1 0.09
Previous research has provided the following MID values
for PH patients:
High MID
values

18. Conclusions – SF-36
• The SF-36 performed poorly overall
• Only Physical Functioning and General Health
Perception scales had adequate psychometric
properties
• It lacks sensitivity and has high levels of
measurement error
• Many of scales appear non-relevant to PH patients
• Supports other evidence showing SF-36 domains
have large minimal important differences (Gilbert et
al, 2009)

19. Conclusions - CAMPHOR
• CAMPHOR scales exhibited excellent psychometric properties
• As it is a disease-specific measure the content is highly relevant
to PH patients
• Low levels of floor and ceiling effects and high test-retest
reliability show the measure is sensitive and has low levels of
random measurement error
• Previous research has shown the CAMPHOR is responsive to
treatment-related change (Meads et al., 2008)
• The Activity Limitations scale of the CAMPHOR provides a PH-
specific measure of physical functioning and offers a better
alternative to the SF-36 Physical Functioning domain and 6
minute walk test

20. References
McKenna SP, Doughty N, Meads DM, Doward LC & Pepke-Zaba J. The
Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR): A
measure of health-related quality of life and quality of life for patients
with pulmonary hypertension. Quality of Life Research (2006) 15: 103–
15.
Meads DM, McKenna SP, Doughty N, Das C, Gin-Sing W, Langley J and
Pepke-Zaba J. The responsiveness and validity of the CAMPHOR Utility
Index. The European Respiratory Journal (2008) 32: 1513–9.
Gilbert C, Brown MC, Cappelleri JC, Carlsson M, McKenna SP.
Estimating a minimally important difference in pulmonary arterial
hypertension following treatment with Sildenafil. Chest (2009) 135:
137-42.