Article Text
Abstract
Introduction and Objectives Existing HRQoL scales have poor content validity for severe asthma as they fail to measure the qualitatively different burdens experienced by the severe asthma population compared to those with mild or moderate asthma, in particular, the side effects of oral corticosteroids (OCS). A new severe asthma quality of life questionnaire (SAQ) has been designed using extensive patient input in qualitative studies as per FDA guidelines. The questionnaire has 16 questions rated on a 1–7 Likert scale and a 100 point global quality of life scale (GQoL) similar to the EQ-5Ds 100 point visual analogue scale (VAS) (SAQ.org.uk).
Methods Consecutive consenting patients attending the severe asthma clinic in Plymouth with severe asthma were invited to participate in a cross sectional survey. Patients completed four questionnaires the SAQ, mini Asthma Quality of Life Questionnaire (miniAQLQ), Asthma Control Test (ACT) and the EQ-5D. Prednisolone dose and frequency of severe exacerbations were obtained from clinic records.
Results 102 participants (64 female, mean age=51 years range 18–79 years), of whom 38 were on maintenance OCS consented to take part, mean FEV1% of 69%. Correlations between the four questionnaires were all above 0.65. Correlations with frequency of severe exacerbations were SAQ 0.31, miniAQLQ 0.31, ACT 0.34. The SAQ’s GQoL correlated with the EQ-5D’s VAS at 0.73. The SAQ was significantly better than the miniAQLQ at predicting the quality of life of patients taking ≥10 mg OCS a day (p<0.05 vs p=0.88). These questionnaires had parallel Results for doses up to 10 mg but above that only SAQ provided differentiation between patients.
Conclusions Preliminary Results indicate that the SAQ may be a more valid measure of quality of life in severe asthma than existing questionnaires. The SAQ maps onto a pre-existing health economic measure, the EQ-5D. Furthermore the SAQ has greater sensitivity to differences in OCS dose compared to the AQLQ. The SAQ will be assessed further in a larger validation study.