OBJECTIVES

Adolescent idiopathic scoliosis (AIS) has significant influence on patients' health-related quality of life (HRQoL). Three-level and five-level EQ-5D-Y (hereafter named Y-3L and Y-5L) are validated utility instruments to assess HRQoL but psychometric properties of the proxy versions remain unknown. This study aims to assess the performance of the proxy-reported Y-5L compared with Y-3L for assessing AIS patients.

METHODS

129 AIS patient-proxy dyads were recruited from a hospital in Hong Kong, China. Patients' caregivers were asked to complete proxy-reported Y-3L and Y-5L. All participants' sociodemographic and patients' clinical characteristics were collected. We assessed redistribution property and ceiling effects from Y-3L to Y-5L. Subgroup analysis was also conducted, where chi-squared test was used to detect differences in proportion of reporting problems. Ability of 'full health' defined by Y-3L and Y-5L to predict clinical outcomes was examined using area under curve (AUC).

RESULTS

Mean age of patients was 13.3±1.4 years, 90.7% were female. Proxies were mostly mothers (71.1%) and only 28.6% received tertiary education or above. Consistencies between Y-3L and Y-5L responses were high for all dimensions (93.8-99.2%). All dimensions showed high ceiling effect (Y-3L:77.5-97.7%; Y-5L:77.5-96.9%) while largest reduction was observed in 'Doing usual activities' (absolute reduction: 2.3%; relative reduction: 2.5%) and 'Feeling worried/sad/unhappy' (absolute reduction: 2.3%; relative reduction: 2.9%). In 'Doing usual activities' dimension, less patients treated with bracing reported full-health status compared to those under observation in Y-3L (P-value: 0.08) and Y-5L (P-value: 0.034), proxies with secondary school or below education and those as mothers (P-value: 0.04 and 0.036 respectively) were more likely to report problems. In AUS analysis, 'full health' defined by Y-3L and Y-5L was not found to predict clinical outcomes.

CONCLUSIONS

The overall performance of proxy-reported Y-3L and Y-5L in AIS patients was appeared to be similar. However, Y-5L is potentially more discriminative among mothers and proxies with lower education levels.