An international study carried out in eight expert centres (including one in France) for fibrodysplasia ossificans progressiva (FOP) has clarified the natural history of the disease and its outbreaks of heterotopic ossifications.
- Of the 114 initial participants (nearly 15% of known cases), aged 4 to 56 years, 33 completed the study with a mean follow-up time of 26.8 months; 66 discontinued participation because they entered a clinical trial.
- During the study, 82 participants reported 229 flare-ups, of which 17.9% involved the upper back, 14.8% the hips and 10.9% the shoulders.
- The initial mean volume of heterotopic ossifications was smallest between the ages of two and eight years and increased with age between 25 and 65 years.
- The mean annualised volume of new heterotopic ossifications was 5 to 10 times greater between 8 and 25 years than after 25 years.
- A restrictive syndrome was present in 32.5% of the participants at the beginning of the study. It was more pronounced in people over 25 years of age with a decreased vital capacity of more than 50% but stable.
While the total volume of heterotopic ossifications and the number of technical aids and environmental adaptations increased substantially over 3 years, POF appears to be more progressive before the age of 25.
