Objective: The purpose of this study was to evaluate the psychometric properties of a novel, patient-reported outcome (PRO) measure, the Hypoparathyroidism (HPT) Symptom Diary (HPT-SD), using data collected during a cross-sectional, noninterventional, observational study. The HPT-SD, developed according to the US Food and Drug Administration PRO guidance, addresses the severity of key symptoms (muscle cramping, tingling and muscle spasms/twitching, fatigue, cognition, emotions) and impacts on sleep, ability to exercise, ability to work, and family relationships.
Methods: Individuals who self-reported HPT were recruited to participate in a paper-based survey collecting demographic and HPT-related clinical and treatment information, patient global impression of severity (PGIS), the HPT-SD, and three supporting measures: Functional Assessment in Cancer TherapyCognitive Function (FACT-Cog), Functional Assessment of Chronic Illness TherapyFatigue Scale (FACIT-Fatigue), and the Hospital Anxiety and Depression Scale (HADS). Item- and scale-level internal consistency reliability, discriminating and construct validity were evaluated. A scoring algorithm was developed based on psychometric and qualitative results.
Results: Participants rated their HPT as moderate (34.6%) or severe (32.7%). Participants did not endorse the most severe response choices (e.g., Very severe) for 4 muscle-related symptom items. Inter-item correlations revealed a pattern of moderate to strong relationships among symptom (r=0.30.8) and impact items (r=0.50.7), providing evidence for two HPT-SD subscales: symptoms and impacts. Construct validity correlations supported a priori convergent validity hypotheses (|r| >0.5) between HPT-SD subscales and the FACT-Cog, FACIT-Fatigue, and HADS. The HPT-SD demonstrated discriminating ability between patients who reported mild versus severe HPT on the PGIS (P<0.05 for 12 out of 13 items).
Conclusions: The HPT-SD is an appropriate measure of HPT-related symptoms and impacts. Severe muscle-related symptoms were reported during qualitative development; all HPT-SD response choices were retained to capture severe symptoms. Future studies should assess the HPT-SD measurement properties using longitudinal study designs.
20 - 23 May 2017
European Society of Endocrinology