Abstract
INTRODUCTION: X-linked retinitis pigmentosa (XLRP) is one of the most severe forms of retinitis pigmentosa, representing 5-15% of all cases. There is a notable gap in understanding the health-related quality of life (HRQoL) impact on carers of people with XLRP, essential for holistic health economic evaluations. The objective of the study is to estimate health state utilities of informal carers for a person with XLRP which can be used in economic modelling. METHOD: Four carer descriptions or "vignettes" were developed for mild, moderate, severe, and completely blind XLRP patient care. The vignettes were based on studies identified in a targeted literature review and validated through qualitative interviews with informal carers and an ophthalmologist. The vignettes were valued using the time trade-off (TTO) method by the general population of Great Britain. Descriptive statistics of the data were analysed. RESULTS: A total of 220 respondents completed the survey. The mean utility value for providing care to someone with mild XLRP was 0.85, decreasing to 0.76 when caring for someone with moderate XLRP and further decreasing to 0.54 when caring for someone with severe XLRP. The mean carer utility declined to 0.42 for complete blindness. CONCLUSION: Mean carer utility declined with increased severity of patient XLRP with the most substantial decline calculated when moving from moderate to severe XLRP. This is the first study to generate utility values reflecting HRQoL of carers of patients with XLRP, by different levels of disease severity, and finds that carer utility decreases with increased XLRP severity in patients.