A Delphi panel to build consensus on assessing disease severity and disease progression in adult patients with hypophosphatasia in the United States

Background Hypophosphatasia (HPP) is an inborn error of metabolism with a variable presentation. We conducted a modified Delphi panel to obtain expert consensus on knowledge gaps regarding disease severity and progression in adult patients with HPP. Methods Healthcare professionals (HCPs) with experience managing adult patients with HPP were recruited to participate in a 3-round Delphi panel (round 1: paper survey and 1:1 interview; rounds 2–3: email survey). Panelists rated the extent of their agreement with statements about disease severity and progression in adult patients with HPP. Consensus was defined as ≥ 80% agreement. Results Ten HCPs completed round 1; nine completed rounds 2 and 3. Consensus was reached on 46/120 statements derived from steering committee input. Disease severity markers in adult patients with HPP can be bone-related (recurrent/poorly healing fractures, pseudo-fractures, metatarsal fractures, osteomalacia) or involve dentition or physiologic/functional manifestations (use of mobility devices/home modifications, abnormal gait, pain). Disease progression markers can include recurrent/poorly healing low-trauma fractures, development of ectopic calcifications, and/or impairment of functional activity. Panelists supported the development of a tool to help assess disease severity in the clinic and track changes in severity over time. Panelists also highlighted the role of a multidisciplinary team, centers with expertise, and the need to refer patients when disease severity is not clear. Conclusions These statements regarding disease severity, progression, and assessment methods address some knowledge gaps in adult patients with HPP and may be helpful for treating HCPs, although the small sample size affects the ability to generalize the healthcare provider experience.