X-linked retinitis pigmentosa: Unravelling the burdens of the inherited retinal disease

Recent literature review reveals dearth of data, highlights need for more research.

Reviewed by Dr Nan Li.

X-linked retinitis pigmentosa (XLRP) is a rare inherited retinal disease for which there is not only a major unmet treatment need but also a need for greater understanding and awareness of its personal and societal burdens, according to authors of a recent article.

Published online in June 2021, the 8-page article presents the findings from a literature search and review conducted to identify and describe the clinical, humanistic, and economic burdens of XLRP or RP in the United States, Japan, France, Germany, Italy, Spain, and the United Kingdom.1 Although the search found a paucity of relevant literature, it is reasonable to conclude from the available evidence that XLRP clearly carries a significant humanistic and economic burden, according to Nan Li, PhD, MHS, MD. Dr Li is the director of access at Janssen Retina DAS in Raritan, New Jersey, and a coauthor of the paper.

“XLRP causes progressive vision loss, with many affected patients becoming legally blind by age 40,” Dr Li said. “Currently there are no approved treatments for XLRP, and unfortunately, we continue to see very limited data on this condition.”

Dr Li also noted that additional research on inherited retinal diseases (IRDs) is crucial to underscore the need for therapies and to highlight their potential to dramatically improve lives of patients and caregivers. “Our identification of the information gaps is an important first step in assessing how best to support people with these conditions,” she said. “Therapies are currently being developed, and that is crucial.”

However, if researchers, regulators, payors, and advocacy groups do not understand the needs of patients with diseases like XLRP, they may not truly realize the potential groundbreaking nature of future treatments and the myriad ways they can improve the lives of patients and their families, Dr Li said.

Key findings

Dr Li said her group’s analysis of the published literature essentially shows the lack of knowledge about the many challenges patients face with early-onset and progressive vision loss due to XLRP.

“We could not identify any studies assessing the humanistic or economic burden of the XLRP form of RP specifically,” Dr Li said. “Given the scarcity of studies focusing on patients with XLRP, we looked to the evidence from studies of the wider RP population to infer conclusions about the burden of XLRP, and we did find articles relating to RP in general.”

From the latter publications, it was learned that with progression of RP, affected individuals experienced a range of psychosocial, functional, physical, and economic burdens. For example, the published reports showed that patients developed feelings of loss, isolation, and fear. They also suffered other negative effects on quality of life resulting from the loss of enjoyment from vision-related hobbies and pastimes. Inability to work because of their impaired vision bore psychosocial consequences for people with RP because of loss of social support as well as economic consequences arising from lost productivity.

“Extrapolating from the findings from the RP-related research and considering first that the onset of disease is earlier for XLRP than RP, and second that XLRP is associated with more rapid progression of vision loss, it is reasonable to expect XLRP may create a greater burden for patients and their caregivers than does RP,” Dr Li said.

Moving forward

The identification of the gap in research to characterize the burdens of XLRP is an important first step in assessing how best to support people affected by the condition. “Our hope is to more fully understand the myriad ways the therapies currently in development for XLRP can potentially improve the lives of patients and families,” Dr Li said. “There is so much more to uncover and know about XLRP and other IRDs and the people living with them.”

Dr Li and colleagues are working with patient advocacy groups to generate more evidence about the cost of these illnesses. In addition, they are looking closely at patient and caregiver well-being, including the emotional burden of disease.

“Last year we partnered with Retina International on a study to estimate the societal disease burden and economic impact of IRDs in the United States and Canada,” Dr Li said. “The study found that individuals living with an IRD incur significant economic costs and reductions in their quality of life.”2

Dr Li also explained that families, friends, government, employers, and society end up taking on significant economic costs as well.

“As we look ahead, our Janssen team anticipates initiating more research on these topics, working hand-in-hand with our stakeholders and partners,” Dr Li said.

Nan Li, PhD, MHS, MD
E: nli47@ITS.JNJ.com
Li has no financial disclosures related to this content.

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References
1. Chivers M, Li N, Pan F, Wieffer H, Slowik R, Leartsakulpanitch J. The burden of X-linked retinitis pigmentosa on patients and society: a narrative literature review. Clinicoecon Outcomes Res. 2021;13:565-572. doi:10.2147/CEOR.S297287
2. Gong J, Cheung S, Fasso-Opie A, et al. The impact of inherited retinal diseases in the United States of America (US) and Canada from a cost-of-illness perspective. Clin Ophthalmol. 2021;15:2855-2866. doi:10.2147/OPTH.S313719