ASBMR 2020: Misdiagnosis common in fibrodysplasia ossificans progressiva

[Author: Laura Cowen]

Patients with fibrodysplasia ossificans progressiva (FOP) wait an average of 1.5 years to receive a correct diagnosis, with more than half initially misdiagnosed, show data from the international FOP registry.

Presenting a poster at the ASBMR 2020 Annual Meeting Virtual Event, Adam Sherman, from the International FOP Association (IFOPA), said the findings show that “greater disease awareness is essential to increase clinicians’ index of suspicion for FOP.”

He explains in the poster that although great toe malformation and heterotopic ossification are early signposts for a definitive clinical FOP diagnosis, the rarity of the condition – affecting less than a thousand people worldwide – means that diagnosis is often missed at birth and delayed for many years.

Sherman reported data from the FOP registry, which was established by IFOPA in 2015 to collect clinical information from patients with FOP and their physicians. It currently includes 415 participants from 67 countries worldwide.

The registry shows that people with FOP develop symptoms at a mean 6.2 years of age, but this can range from 0 to 45 years. The mean age at correct diagnosis is 8.3 years, with a range of 0 to 48 years.

However, Sherman and co-authors note that patients who have the classical FOP R206H mutation are diagnosed at a younger age than those who have an FOP variant mutation, at a mean of 7.0 versus 18.6 years.

The registry data also revealed that the diagnostic journey for FOP has shortened in recent years. Prior to 2016, it took an average of 2.2 years to receive a correct diagnosis for FOP, but since 2016 this has fallen to 1.5 years.

The researchers suggest that this reduction “is likely to due to increased overall awareness of FOP due to media coverage, research and drug development activity.”

In spite of the reduction in time to diagnosis, the average number of physician specialties that patients see prior to receiving a correct diagnosis has remained stable, at 3.3, over time.

Just over half (52.5%) of registry participants have reported initially receiving a misdiagnosis, most commonly cancer (29%), juvenile fibromatosis (13%), myositis ossificans (10%), and Klippel-Feil Syndrome (4%).

Definitive diagnoses were most likely to come from orthopedists (25.5%), geneticists (25.1%), or pediatricians (13.7%), overall, with rheumatologists playing a larger role (19.0% of diagnoses) when first symptom onset occurs after 12 years of age.

The registry data also showed that misdiagnosis rates vary among physician specialties. Specifically, general physicians are 8.9 times more likely to make an incorrect diagnosis for every correct diagnosis given, while the ratio is 5.5 for pediatricians, 2.5 for orthopedists, 1.9 for rheumatologists, and 0.9 for geneticists.

Sherman and co-researchers say that “[t]hese rates provide a roadmap for further disease awareness education within these medical specialties.”

And they conclude: “Patient registries can help medical communities better understand the diagnostic journey taken to make the correct diagnosis, which is critical to ensuring that patients receive the proper clinical care and support services.”

FOP clinical diagnosis quiz image references

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