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Content Validity of Two Generic Preference-Based Measures in Retinitis Pigmentosa, Including X-Linked Retinitis
Louis S Matza1, Timothy A Howell2, Qiaoyi Zhang3
1PPD Evidera Patient-Centered Research, Thermo Fisher Scientific, 168 3rd Ave, Waltham, MA, 02451, USA. louis.matza@thermofisher.com.
Pharmacoeconomics - Open
|January 23, 2026
Summary
Generic health measures like EQ-5D-5L and HUI have limited content validity for X-linked retinitis pigmentosa (XLRP) patients. Key concepts impacting quality of life, such as visual symptoms and driving, were missing from these instruments.
Area of Science:
- Ophthalmology
- Health Economics
- Patient-Reported Outcomes
Background:
- Retinitis pigmentosa (RP) encompasses a group of retinal diseases causing night blindness and visual field/acuity impairment.
- X-linked RP (XLRP) represents the most severe form of RP.
- The utility of generic preference-based measures (GPBMs) for conditions like XLRP is often debated.
Purpose of the Study:
- To evaluate the content validity of the EQ-5D-5L and Health Utilities Index (HUI) in patients diagnosed with XLRP or other forms of RP.
- To identify specific concepts relevant to the quality of life of (XL)RP patients that may be missed by current instruments.
Main Methods:
- Qualitative interviews were conducted with 23 US-based patients diagnosed with (XL)RP.
- Interviews involved concept elicitation to understand the impact of (XL)RP on quality of life.
- Participants completed the EQ-5D-5L and HUI, followed by feedback on instrument clarity, relevance, and comprehensiveness.
Main Results:
- Participants reported impacts of (XL)RP, with some overlap with EQ-5D-5L and HUI domains (e.g., emotional state, daily activities).
- Both EQ-5D-5L and HUI were generally found to be clear and understandable.
- A significant number of participants identified crucial missing concepts in both instruments, including visual symptoms, driving ability, light sensitivity, and engagement in enjoyable activities.
Conclusions:
- The EQ-5D-5L and HUI capture some relevant aspects for (XL)RP patients but lack specific concepts crucial to this population.
- The identified content gaps may limit the instruments' ability to accurately reflect disease severity and impact on quality of life.
- Alternative methods for assessing health utilities in (XL)RP patients should be considered.
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