Background A rare disease (RD) is a disease affecting less than one in 2,000 people. In Hong Kong, one in 67 people is living with one or more RDs. RD patients live with different degrees of life-long physical or intellectual disability and often require special care. Approximately 80% of the RDs are genetic in origin, in which some are with childhood onset. The paediatric RD patients constitute 35% of the whole RD population in Hong Kong.

Objectives To investigate the health-related quality of life (HRQoL) of patients and care-givers in the RD population in Hong Kong.

Methods This was a cross-sectional study between 25 April and 16 October 2020. The EuroQol 5-Dimension 3-Level (EQ-5D-3L), a generic preference-based patient-reported outcome measure instrument, was distributed to the RD patients and care-givers through RD patient groups to describe HRQoL. The five dimensions assessed were mobility, self-care, usual activity, anxiety/depression and pain/discomfort. The three levels represent severity in each dimension, with Level 1 indicating absence of problem and Level 3 indicating extreme problems. The EQ-5D-3L was available in self-complete version, and proxy version for care-givers of patients mentally or physically incapable of reporting. In the proxy version, care-givers reported the HRQoL for both patients and themselves. A reverse crosswalk algorithm was used to generate five-level (EQ-5D-5L) utility scores from EQ-5D-3L profiles with reference to the Hong Kong value set, to allow comparison with the general population. The utility score ranges from 0 (death) to 1 (perfect health), with negative values indicating worse-than-death health states.

Results During the study period, 284 valid and independent responses were collected, including 165 patients from self-complete version and 119 patients and their care-givers from proxy version. The median age of patients and care-givers participated were 32.1 and 42.9, respectively. The mean utility score of patients and care-givers were 0.5207 and 0.7992, both significantly lower than that of the normal population, 0.9186 (p<0.0001). 77 (65%) of the 119 patients from the proxy version were below 18 years old, with a mean utility score of 0.4504. Among all 284 patients, patients able to self-report had a higher mean utility score, 0.5753, than patients requiring a care-giver for reporting, 0.4449. Patients requiring a proxy reported more severe problems in self-care and usual activities dimensions, while their care-givers reported more problems in anxiety/depression dimension. Overall, only 16% of patients and 29% of care-givers had Level 1 in all five dimensions. In contrast, five (3%) patients in self-complete version and 25 (21%) patients in proxy version were reported with negative utility scores, in which two had Level 3 in all five dimensions. Out of the 30 patients with negative utility scores, 93% had no self-care ability, 87% were unable to perform usual activities and 67% were confined to bed.

Conclusions This is the first study in Asia to demonstrate that RD as a group has a negative impact on the HRQoL of both patients and care-givers. It illustrated the impact of RDs on different aspects of quality of life, which warrants exceptional care from policy makers and the society.