Psychometric performance of the CAMPHOR and SF-36 in pulmonary hypertension

Abstract

Objectives
The Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) and the Medical Outcomes Study Short Form 36 (SF-36) are widely used to assess outcome in pulmonary hypertension (PH) patients. The CAMPHOR is a PH-specific measure consisting of three scales; symptoms, activity limitations and needs-based QoL. The SF-36 is a generic health status questionnaire consisting of 36 items and eight domains. The aim of this study was to compare the psychometric properties of these two measures in a population with PH.

Methods
Participants were recruited from six specialist PH centres in Australia and New Zealand. They completed the CAMPHOR and SF-36 at two time points, two weeks apart. The questionnaires were assessed for distributional properties (% scoring minimum and % scoring maximum), internal consistency (Cronbach's alpha), test-retest reliability (minimum required correlation coefficient = 0.85) and construct validity (CAMPHOR scores by WHO functional classification).

Results
The sample comprised 65 participants (mean (SD): age = 57.2 (14.5) years; male n (%): 14 (21.5)). Most of the participants were in WHO functional class II (27.7%) or III (61.5%). A high proportion of participants recorded the maximum score for the SF-36 social functioning (21.3%) and role emotional (25.0%) domains, signifying insensitivity. Test-retest reliability was below the required level for six of the eight SF-36 domains, indicating high levels of random measurement error. Three of the SF-36 domains did not distinguish between WHO functional classes. Only two of the SF-36 domains (role physical and general health perceptions) met the full psychometric criteria of the study. In contrast, all CAMPHOR scales exhibited good test retest reliability and distinguished significantly between WHO functional classes.

Conclusions
The CAMPHOR has superior psychometric properties, compared to the SF-36, in the assessment of QoL in individuals with PH.