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Twiss J, Ben-L’amri M, McKenna SP
February 2012
Galen Research Ltd.
Comparison of the CAMPHOR
and SF-36 for Pulmonary
Hype...
Introduction
• CAMPHOR and SF-36 both widely used measures in PH
• CAMPHOR is the only disease-specific measure for PH
• C...
Methodology
• Sample: 65 Australian PH patients
• CAMPHOR and SF-36 data available at two
time points
• Measures were asse...
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...
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
Floor and Ceiling effects – CAMPHOR Time 1
0%
5%
10%
15%
20%
25%
30%
Symptoms Activity Limitations QoL
Floor effect Ceilin...
Interpretation of findings
• Three of the eight SF-36 domains had high
ceiling effects
• This indicates that domains lack ...
Internal consistency – interpretation of
findings
• All domains and scales showed adequate
internal consistency
• This ind...
Test-retest reliability
Measure Item Test-retest % explained
variance (r2)
SF-36 Physical Functioning .93 86
General Healt...
Interpreting test-retest data: confidence
intervals for the SF-36 and CAMPHOR
Test-retest Time 1 mean SEM* Corresponding C...
Interpreting test-retest data– SF-36
• Six of eight domains below 0.85
• Large confidence intervals observed
• This indica...
Interpreting test-retest data–CAMPHOR
• The CAMPHOR scales had excellent test-retest
reliability
• Narrow confidence inter...
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)
M...
Known-Groups validity – CAMPHOR
Symptoms Activity Limitations QoL
TIME 1
WHO Classification
1 & 2 10.4 (5.3) 7.2 (5.7) 7.3...
Interpreting known-groups validity
findings – SF-36
• Bodily Pain, Role-Emotional and Mental
Health domains did not distin...
Interpreting known-groups validity data –
CAMPHOR
• All scales were able to distinguish between
WHO classes
• The CAMPHOR ...
Previous research showing MID values
Measure Scale Score range MID value
SF-36 Physical functioning 0-100 13
Role-physical...
Conclusions – SF-36
• The SF-36 performed poorly overall
• Only Physical Functioning and General Health
Perception scales ...
Conclusions - CAMPHOR
• CAMPHOR scales exhibited excellent psychometric properties
• As it is a disease-specific measure t...
References
McKenna SP, Doughty N, Meads DM, Doward LC & Pepke-Zaba J. The
Cambridge Pulmonary Hypertension Outcome Review ...
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Comparison of the CAMPHOR and SF-36 for Pulmonary Hypertension (PH) patients

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

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Comparison of the CAMPHOR and SF-36 for Pulmonary Hypertension (PH) patients

  1. 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. 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. 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. 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. 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. 6. Floor and Ceiling effects – CAMPHOR Time 1 0% 5% 10% 15% 20% 25% 30% Symptoms Activity Limitations QoL Floor effect Ceiling effect
  7. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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.

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