emPHasis-10: development of a health-related quality of life measure in pulmonary hypertension

Abstract

The aim of this study was to develop a measure of the impact of pulmonary hypertension (PH) on health-related quality of life (HRQoL) as there is a need for a short, validated instrument that can be used in routine clinical practice. Interviews were conducted with 30 PH patients to derive 32 statements, which were presented as a semantic differential six-point scale (0-5), with contrasting adjectives at each end. This item list was completed by patients attending PH clinics across the UK and Ireland. Rasch analysis was applied to identify items fitting a uni-dimensional model. 226 patients (mean age 55.6±14 years; 70% female) with PH (82% had pulmonary arterial hypertension) completed the study questionnaires. 10 of the 32 items demonstrated fit to the Rasch model (Chi-squared 16; p>0.05) and generated the emPHasis-10 questionnaire. Test-retest (intraclass correlation coefficient 0.95, n=33) and internal consistency (Chronbach's α=0.9) were strong. emPHasis-10 scores correlated consistently with other relevant measures and discriminated subgroups of patients stratified by World Health Organization functional class (ANOVA F=1.73; p<0.001). The emPHasis-10 is a short questionnaire for assessing HRQoL in pulmonary arterial hypertension. It has excellent measurement properties and is sensitive to differences in relevant clinical parameters. It is freely available for clinical and academic use.

Figure 1–

Distribution of a) patients and b) items based on Rasch logit locations showing the distributions of patient health-related quality of life severity and item severity (locations) along the same linear scale measured in logits. Most items are located between -2 and +2 logits. Total n=226, mean±sd 0.200±1.334.

Figure 2–

The final emPHasis-10 questionnaire. The Pulmonary Hypertension Association UK (Rotherham, UK) intends to make this questionnaire free to use by both the clinical and academic communities. It can be downloaded free of charge from the Pulmonary Hypertension Association UK website (www.phassociation.uk.com) and reproduced without cost for clinical and academic use. Different language versions will be made available in due course. Reproduced with permission from the Pulmonary Hypertension Association UK.

Figure 3–

Mean emPHasis-10 scores for each World Health Organization (WHO) functional class. Error bars represent 95% confidence intervals.