Abstract
Patients with Hereditary Spastic Paraplegia (HSP) report reduced quality of life (QoL) compared to the general population. Generic QoL measures do not address disease-specific aspects such as spasticity, access to specialty HSP clinics, and bladder symptoms. We designed and validated a HSP-specific QoL scale (HSPQoL), intended for use in standard clinical settings and clinical trials. HSP-specific items were added to the RAND 36-Item Short Form Health Survey (SF-36) to form HSPQoL. Following literature review/expert input, 23 items were presented to a panel of HSP clinicians, patients, and patient representatives ( n = 12) using a modified Delphi process. Items were ranked for clarity and relevance (inclusion criteria: 80% consensus). 21/23 items met the inclusion criteria. Interviews with patients ( n = 5) assessed suitability, comprehension, clarity, and response options to additional items. Based on cognitive interview results, items were modified ( n =4), removed ( n =7), or added ( n =3). Sixty-one patients completed the HSPQoL and EQ5D-5L for evaluation of construct validity and 19 patients repeated the HSPQoL for evaluation of test–retest reliability. 15/17 additional items moderately to strongly correlated with pre-existing SF-36 subscores (Spearman correlation 0.319–0.771, p < 0.05). Exploratory factor analyses showed high percentage of variance in the first component (> 45%). HSPQoL demonstrated good internal consistency (Cronbach alpha 0.94), test–retest reliability (ICC 0.957), and convergent validity with EQ5D-5L (r = 0.725). In conclusion, demonstrated validity and reliability of the HSPQoL confirms consideration of its use for assessing specific QoL in individuals with HSP.