OBJECTIVES: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare genetic disorder characterized by progressive, cumulative, and irreversible heterotopic ossification in soft and connective tissues. This study sought to identify, describe, and substantiate important and relevant signs, symptoms, and impacts of FOP and FOP flare-ups experienced by adolescents and adults with the condition.

METHODS: With institutional review board approval, qualitative interviews were conducted with members of the International FOP Association who consented to participate and met inclusion criteria. Interviews were conducted by telephone using a semi-structured interview guide. Audio-recordings of interviews were transcribed and anonymized; transcripts were analyzed to evaluate saturation and generate frequency counts and descriptions of FOP signs, symptoms, and impacts.

RESULTS: Participants (N=12, 9 female) ranged from 12 to 60 years of age (mean=34.7, standard deviation=14.7). Saturation analysis provided evidence of the adequacy of sample size. Participants reported 18 FOP signs and symptoms, most frequently pain (reported by n=12 participants), swelling (n=11), malformed great toes (n=6), redness (n=6), and stiffness (n=6). During flare-ups, pain and swelling were frequently reported as being more severe. Participants reported 24 FOP and FOP flare-up impacts across nine impact domains affecting all aspects of life. Most frequently reported impacts were impaired mobility (reported by n=11 participants), impacted self-care (n=9), sadness (n=6), difficulty dressing (n=5), interference with activities of daily living (n=5), and difficulty with eating and social activities (n=4 each).

CONCLUSIONS: Individuals with FOP experience a variety of signs and symptoms that become more severe during flare-ups. FOP progression is disabling, emotionally challenging, and severely impacts physical function, self-care, daily activities, and social activities. Results from this study will be of immediate use to clinical researchers developing patient-centered outcome assessments for clinical trials and practice.