Table 1 Baseline demographic and clinical characteristics of FOP patients

Sex: boys/girls, n (%)

7 (54) / 6 (46)

Onset age, Me (25%; 75%), years

1.0 (0.5; 2)

‒ Mean (min; max), years

1.5 (0.1; 6.0)

Age of tofacitinib administration, Me (25%; 75%), years

10.4 (4.4;16.5)

‒ Mean (min; max), years

10.2 (2.2;19.6)

The time between disease onset and tofacitinib administration, Me (25%; 75%), years

4.2 (3.4;11.5)

‒ Mean (min; max), years

7.3 (0.75;18.3)

Diagnostics delay, Me (25%; 75%), months

15 (3;73)

‒ Mean (min; max), months

44 (1;165)

Features of FOP, n = 13

Malformed great toes^*, n (%)

13 (100)

Short malformed thumbs^*, n (%)

9 (69)

Сervical spine abnormalities^*, n (%)

13 (100)

Multiple heterotopic ossifications^*, n (%)

13 (100)

Peripheral osteochondromas^*, n (%)

9 (69)

CAJIS Me (25%; 75%), score

7 (6; 14)

‒ Mean (min; max), score

9.4 (3;17)

ACVR1 gene variants:

‒ typical: c.617 G > A p.Arg206His, n (%)

12 (92)

‒ ultra-rare variant: с.983 G > A (p.Gly328Glu), n (%)

1 (8)

Imaging

Bilateral sacroiliitis

6/7 (86%)

Bilateral hip joints effusion:

Ultrasound investigation

13/13

Magnetic resonance imaging

7/7

Previous treatment experience n (%)

Nonsteroid anti-inflammatory drugs

13 (100)

Corticosteroids, oral

13 (100)

Corticosteroids, intravenous

8 (62)

Bisphosphonates

8 (62)

Baseline treatment experience, n (%)

Nonsteroid anti-inflammatory drugs

13 (100)

Corticosteroids, oral

8 (62)

Corticosteroids, intravenous

2 (15)