Psychometric evaluation of the hypoparathyroidism symptom diary

Abstract

Purpose

To conduct an initial psychometric evaluation of the reliability and validity of the Hypoparathyroidism Symptom Diary (HPT-SD).

Patients and methods

Data were collected during a cross-sectional, observational study. Participants with self-reported hypoparathyroidism (HPT) completed the HPT-SD, the Functional Assessment in Cancer Therapy–Cognitive Function (FACT-Cog), the Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-Fatigue), and the Hospital Anxiety and Depression Scale (HADS) measures. Item- and scale-level internal consistency reliability, known-groups validity, and construct validity were evaluated. Subscales were identified and preliminary scoring algorithms were developed.

Results

The study included 52 participants (mean age, 51 years). Overall, the measurement properties of the HPT-SD were very good. Item-level response frequency distributions showed evidence of possible floor effects for four muscle-related symptom items. Inter-item correlations revealed a pattern of relationships among symptom items (r=0.3–0.8) and among impact items (r=0.5–0.7) and provided evidence for two HPT-SD subscales: Symptoms and Impacts. Construct validity correlations supported a priori convergent validity hypotheses (|r|≥0.4) between HPT-SD subscales and the FACT-Cog, FACIT-Fatigue, and HADS. Mean HPT-SD Symptom and Impact scores were in the expected direction and significantly different between subgroups of patients with high and low HPT disease severity.

Conclusion

Results indicate that the HPT-SD is an appropriate measure of HPT-related symptoms and impacts. Floor effects may be attributed to the observational study design: participants manage symptoms with calcium and active vitamin D supplements prior to an escalation in severity. Future studies should assess the HPT-SD measurement properties using longitudinal study designs.

Keywords:

• hypoparathyroidism
• symptom
• psychometric
• validation
• impacts
• patient-reported outcome

Supplementary materials

Table S1 Treatment characteristics (N=52)

Table S2 Known-groups results

Acknowledgments

Under the direction of the authors and funded by Shire Int GmbH (Zug, Switzerland), editorial support and writing assistance was provided by Kate Lothman, Lindsey Norcross, and John Forbes of RTI Health Solutions (Research Triangle Park, North Carolina).

This research was performed under a research contract between RTI Health Solutions and Shire Human Genetic Therapies and was funded by Shire Human Genetic Therapies.

This research was presented at the 19th European Congress of Endocrinology (May 20−23, 2017; Lisbon, Portugal) as a poster presentation with interim findings. The poster’s abstract was published in Endocrine Abstracts (2017) 49 EP1263: DOI 10.1530/endoabs.49.EP1263.

Dr Alan Krasner current affiliation is Crinetics Pharmaceuticals, Inc., San Diego, California, United States.

Disclosure

This study was performed under a research contract between RTI Health Solutions and Shire Human Genetic Therapies and was funded by Shire Human Genetic Therapies. Theresa Coles, Lauren Nelson, Nimanee Harris, and Susan Martin are employees of RTI Health Solutions, a unit of RTI International, a not-for-profit research organization that provides consulting and research services to governmental organizations, businesses, and pharmaceutical companies. Kristina Chen and Montserrat Vera-Llonch are employees of Shire Human Genetic Therapies. Alan Krasner was an employee of Shire Human Genetic Therapies when this research was conducted. The authors report no other conflicts of interests in this work.