OBJECTIVES: Fibrodysplasia ossificans progressiva (FOP) describes an ultra-rare, severely disabling, progressive, chronic connective tissue disease. Caused by a mutation in repair mechanisms, which induces soft tissue to be ossified spontaneously or when damaged. Currently, only palliative measures exist. FOP could be detected with birth, but diagnosis is often delayed.

Only few epidemiological data exist in Germany. FOP has a specific ICD-Code. Here inpatient stays of 44 FOP-patients (German advocacy group members) with confirmed diagnosis had been examined over 10 years and compared to all FOP coded hospital cases in Germany, to improve judgement of the epidemiologic situation.

METHODS: Reports from German DRG-Institute (InEK) and Statistical Office (DESTATIS) for 2010-2021 were analyzed and compared with confirmed patients. Analysis with Microsoft-Access® 2019.

RESULTS: 1,030 hospital cases with main diagnosis FOP were registered in 10 years (2011-2020). Thereof 403 (38.8%) from the defined 44 patients’-group, alive in 2022. Averaging 0.97 hospitalizations per live-year, peaking between 12y-16y with more than two annual stays. 217 (21.1%) further cases could be attributed to 50 estimated further patients, with defined age, gender, and home-state. The reminder was ruled out as misdiagnoses or other reasons.

Mean-age in the defined group 28.6y (SD 14.6y, median 28y), female 61.4%, 59% living in wealthier states. The joint group mean-age was (SD 16.3y, median 32y), female 52.0%, 51% wealthier states.

The defined group was first hospitalized with 2.8y (SD 2.2y). Thus, the estimation will miss few, estimated six, infants. Thus, confirmed, and estimated patients and infants add up to 100, translating into a prevalence of 0.12/100,000 inhabitants and an annual incidence of 0.002/100,000.

CONCLUSIONS: The FOP in Germany is an ultra-rare disorder. The comparison of hospitalization patterns of a group of diagnosed patients allowed an estimation of epidemiologic parameters. Improved data could be provided by systematic registry-participation.