Burden of Disease in Adult Patients with Hypophosphatasia: Results from Two Patient-Reported Surveys

• Published in: Metabolism, clinical and experimental Vol. 65; no. 10; pp. 1522 - 1530
• Main Authors: Weber, Thomas J, Sawyer, Eileen K, Moseley, Scott, Odrljin, Tatjana, Kishnani, Priya S
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2016
• Subjects: Activities of Daily Living; Adolescent; Adult; Age of Onset; Aged; Ambulatory Care - statistics & numerical data; Burden of illness; Cost of Illness; Endocrinology & Metabolism; Female; Fractures, Bone - epidemiology; Fractures, Bone - etiology; Gait Disorders, Neurologic - epidemiology; Gait Disorders, Neurologic - etiology; Humans; Hypophosphatasia; Hypophosphatasia - physiopathology; Male; Metabolic bone disease; Middle Aged; Mobility Limitation; Muscle Weakness - epidemiology; Muscle Weakness - etiology; Pain - epidemiology; Pain - etiology; Patient reported outcomes; Quality of Life; Surveys and Questionnaires; Treatment Outcome; Young Adult; CPAP; TNSALP; HIPS; Hypophosphatasia Outcomes Study Telephone Interview; inorganic pyrophosphate; PPi; HOST; HPP; Hypophosphatasia; patient reported outcomes; continuous positive airway pressure; burden of illness; QoL; SF-36; Hypophosphatasia Impact Patient Survey; PLP; 12-item Short Form Health Survey Questionnaire version 2; metabolic bone disease; tissue-nonspecific alkaline phosphatase; 36-item Short Form Health Survey Questionnaire; quality of life; SF-12v2; pyridoxal-5’-phosphate; Burden of illness; Patient reported outcomes; Metabolic bone disease
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/j.metabol.2016.07.006

Abstract Background Hypophosphatasia (HPP) is a rare metabolic bone disease caused by loss-of-function mutation(s) in the tissue-nonspecific alkaline (TNSALP) phosphatase gene, which manifests as rickets and/or osteomalacia with systemic complications and affects patients of all ages. The burden of disease is poorly characterized in adult patients. Aims We assessed patient-reported burden of disease using two surveys reasonably specific for HPP symptomatology, the Hypophosphatasia Impact Patient Survey (HIPS) and the Hypophosphatasia Outcomes Study Telephone interview (HOST). Methods Patients with HPP were invited to participate via patient advocacy groups or their medical provider. Survey questions captured demography, HPP-related medical history, mobility, and health-related quality of life (using Short Form 12 [version 2] Health Survey [SF-12v2]) via internet report (HIPS) or telephone interview (HOST). Results One hundred and twenty-five adults responded (mean [standard deviation, SD] age: 45 [14.3] years). Eighty-four patients (67%) reported pediatric-onset of their symptoms. Common clinical features in the study population included pain (95% of patients), fractures (86% of patients) muscle weakness (62%) and unusual gait (52%). Use of assistive devices for mobility (60%) was also prevalent. Twenty-six percent of patients reported more than 10 fractures. Seventy-four percent of patients had undergone orthopedic/dental surgical procedures. The health profile of patients responding on the SF-12 showed a broad and substantial impact of HPP on health-related quality of life, with domains related to physical ability showing the greatest decrement compared to normative data. Conclusions In aggregate, these data indicate that HPP can confer a high burden of illness in adulthood.