Abstract
BACKGROUND: Leber hereditary optic neuropathy (LHON) is a rare, maternally inherited, mitochondrial disease resulting in sudden, progressive central vision loss. The condition affects numerous aspects of daily life, functioning and overall health-related quality of life (HRQL), which may spillover to carers. METHODS: Two studies were designed to estimate patient utilities associated with varying visual acuity in LHON (study 1) and to explore carer burden (study 2). In study 1, eight LHON health state vignettes (mild vision loss [LogMAR < 0.3] through to light perception [LogMAR ≥ 4]) were valued by the UK and Republic of Ireland (ROI) general pubic using the Health Utilities Index- 3 (HUI-3) and EQ-5D in an online survey (N = 360) and in time trade-off interviews (TTO; n = 120). In study 2, nine carers completed in-depth interviews exploring carer burden, the Care-related Quality of Life instrument (CarerQol), EQ-5D-5L and the Work Productivity and Activity Impairment Questionnaire (WPAI). RESULTS: Study 1 demonstrated lower utilities for people with worse visual function. Mild vision loss (LogMAR < 0.3) was rated as 0.84 (HUI-3), 0.79 (EQ-5D) and 0.88 (TTO). Light perception (LogMAR ≥ 4), the most severe health state, was rated as 0.18 (HUI-3), 0.34 (EQ-5D), and 0.36 (TTO). In study 2, qualitative findings revealed substantial burden for many carers and family members. The most prominent impacts were emotional (e.g., guilt, devastation), especially related to the maternal inheritance of LHON. Impacts to carers' daily life, social life and relationships, work, and finances were also described. Standardised measures identified little impact on HRQL (EQ-5D-5L = 0.89), but some carer related burden (CarerQol-7D = 78.4). The WPAI revealed an overall work impairment of 15% and activity impairment of 37%. CONCLUSIONS: Findings suggest the HUI-3 may be more sensitive to the HRQL impact of vision loss compared to the EQ-5D and TTO method. The data indicate the potential value of an effective treatment for LHON. Qualitative findings describe the impact of LHON on carers. However, the burden described in the qualitative data was incongruent with quantitative measures, particularly the EQ-5D-5L. This demonstrates the value of conducting mixed-methods research and the importance of selecting measures which capture population-relevant concepts.