Psychometric validation of the Hypoparathyroidism Patient Experience Scales (HPES).

Background: Hypoparathyroidism (HP) is a rare endocrine disorder characterized by absent or inappropriately low levels of circulating parathyroid hormone with associated significant physical and cognitive symptoms. This study evaluated the psychometric properties of the Hypoparathyroidism Patient Experience Scales (HPES), which were developed as disease-specific, patient-reported outcome (PRO) measures to assess the symptoms and impacts associated with HP in adults.

Methods: Data from a non-interventional, observational study (N = 300) and a Phase 2 clinical trial (N = 59) were used in the psychometric evaluation. Observational and trial assessments included: an online validation battery (baseline or screening) and retest (approximately 2 weeks after baseline or screening). In the trial, the primary efficacy endpoint was assessed at week 4 through re-administration of the HPES and validation battery subset. The observational study's larger sample size allowed for evaluation of the HPES descriptive properties, scoring algorithm, test-retest reliability, and construct validity. The trial data examined responsiveness, meaningful within-patient change estimates, and treatment impact on HPES scores.

Results: Demographic and self-reported medical characteristics results were similar across the 2 studies. Factor analysis confirmed domains in the HPES-Symptom (n = 2) and HPES-Impact (n = 4). For both measures, total and domain scores demonstrated acceptable reliability and validity for both the observational and trial samples. Internal consistency evidence was strong. Test-retest reliability estimates generally approached the recommended 0.70 threshold. The construct validity correlations with other PRO measures were mainly as hypothesized, thus supporting the HPES scores and constructs. Mean scores for both measures also differed as anticipated and significantly across known-groups, thus providing evidence for the scores discriminating between meaningful groups. Trial results supported both HPES total and domain scores' ability to detect change. The difference in mean total and domain scores for both measures demonstrated statistically significant improvements for TransCon PTH compared to placebo treated subjects despite the small sample and a short 4-week duration on fixed, non-optimized doses.

Conclusions: The HPES were found to be conceptually sound with adequate evidence supporting their reliability and validity. Incorporation of the HPES into clinical and research settings will help to further elucidate and assess the patient experience of living with HP and identify treatment differences.