Use of nailfold capillaroscopy for evaluation of disease activity in juvenile dermatomyositis: Results of a two-center retrospective study

Table 1 Modified disease activity score index

Parameters	Scored item	Options	Score
Muscle DAS (0-7)	Muscle strength	No muscle weakness (gMMT 68-70, MMT8 78-80)	0
		Minimal muscle weakness (gMMT 63-67, MMT8 72-77)	1
		Moderate muscle weakness (gMMT 56-62, MMT8 64-71)	2
		Severe muscle weakness (gMMT 0-55, MMT8 0-63)	3
	Functional status	No limitation on activity	0
		Activities limited at the extracurricular level	1
		Activities limited at the school/work level	2
		Activities limited at the self-care level	3
	Arthritis	Absent	0
		Present	1
Skin DAS (0-5)	Erythema	No erythema	0
		Local erythema (joints and face)	1
		Widespread erythema	2
	Heliotropic rash	Absent	0
		Present	1
	Gottron papules	Absent	0
		Present	1
	Vasculitis	Absent	0
		Present (nailfold abnormality)	1
Total score (0-12)

DAS: Disease activity score; gMMT: Global manual muscle test; MMT8: Manual muscle test 8.

Table 2 Clinical and laboratory characteristics of the studied groups (data from the day of capillaroscopy), n (%)

Parameters	Active JDM (n = 26)	Inactive JDM (n = 23)	P value
Age at onset, years, median (IQR)	6.0 (5.0, 8.0)	6.0 (4.5, 9.0)	0.755
Age at capillaroscopy, years, mean ± SD (95%CI)	9.69 ± 4.34 (7.94-11.45)	11.4 ± 3.9 (9.7-13.1)	0.156
Disease duration before diagnosis, months, median (IQR)	3.5 (2.0-5.8)	3.0 (2.0-5.5)	0.976
Disease duration before capillaroscopy, months, median (IQR)	36.0 (11.5-52.5)	56.0 (15.0-86.0)	0.161
DAS mod at diagnosis, mean ± SD (95%CI)	7.8 ± 1.9 (7.0-8.6)	7.7 ± 1.8 (6.9-8.4)	0.772
DAS mod at capillaroscopy, median (IQR)	5.0 (4.0, 7.0)	1.0 (1.0, 2.0)	< 0.001
Clinical features
Malaise	13 (50.0)	2 (8.7)	0.002
Headache	2 (7.7)	0 (0.0)	0.491
Fever	3 (11.5)	0 (0.0)	0.237
Erythema	21 (80.8)	8 (34.8)	0.001
Heliotrope rash	20 (76.9)	3 (13.0)	< 0.001
Gottron papules	25 (96.2)	7 (30.4)	< 0.001
Raynaud’s syndrome	8 (30.8)	2 (8.7)	0.080
Muscle weakness	17 (65.4)	5 (21.7)	0.002
Activities limited	11 (42.3)	3 (13.0)	0.030
Arthritis	3 (11.5)	4 (17.4)	0.612
Arthralgia	3 (11.5)	4 (17.4)	0.692
Calcinosis	3 (11.5)	4 (17.4)	0.692
Cardiovascular system disorders	3 (11.5)	1 (4.3)	1.000
Digestive system disorders,	1 (3.8)	0 (0.0)	1.000
Laboratory features
HGB g/L, mean ± SD	130.9 (13.8)	130.4 (12.7)	0.905
RBC (1012/L), mean ± SD	4.7 (0.4)	4.7 (0.5)	0.847
WBC (109/L), median (IQR)	6.2 (5.4, 8.8)	6.5 (5.8, 8.0)	0.667
PLT (109/L), mean ± SD	339.6 (67.7)	350.8 (72.7)	0.579
ESR (mm/hour), median (IQR)	8.5 (4.3, 17.0)	8.0 (5.0, 9.5)	0.393
Ferritine (ng/mL), median (IQR)	39.7 (32.0, 72.0)	40.0 (33.4, 58.1)	0.942
CRP (mg/L), median (IQR)	1.2 (0.2, 2.7)	1.4 (0.5, 1.8)	0.748
ALT (IU/L), median (IQR)	27.5 (13.5, 47.0)	16.0 (11.5, 21.5)	0.071
AST (IU/L), median (IQR)	34.5 (22.3, 43.8)	26.0 (23.5, 32.0)	0.061
Common protein (g/L), median (IQR)	70.0 (67.3, 73.0)	69.0 (66.5, 71.0)	0.622
Albumin (g/L), mean ± SD	40.6 (4.0)	43.3 (2.9)	0.036
Bilirubin (µmol/L), median (IQR)	7.0 (4.8, 10.3)	8.8 (5.5, 11.7)	0.312
CPK (IU/L), median (IQR)	107.0 (79.0, 198.0)	77.0 (54.5, 89.5)	0.022
LDH (IU/L), median (IQR)	260.0 (224.0, 341.0)	220.0 (198.5, 233.5)	0.006
Fibrinogen (g/L), median (IQR)	2.6 (2.4, 2.7)	2.8 (2.6, 3.2)	0.119
D-dimer (ng/mL), median (IQR)	254.5 (144.3, 421.8)	228.0 (174.0, 239.0)	0.903
RF (IU/mL), median (IQR)	4.6 (3.3, 6.3)	6.0 (4.8, 6.3)	0.284
Treatment at capillaroscopy
GC	22 (84.6)	12 (52.2)	0.028
Pulse-GC	8 (30.8)	0 (0.0)	0.005
GC dose at capillaroscopy, mg/kg/day in prednisolone eq, median (IQR)	0.4 (0.1, 1.0)	0.2 (0.0, 0.3)	0.019
MTX	16 (61.5)	12 (52.2)	0.623
MMF	2 (7.7)	1 (4.3)	0.623
IVIG	5 (19.2)	0 (0.0)	0.054

JDM: Juvenile dermatomyositis; IQR: Interquartile range; CI: Confidence interval; DAS: Disease activity score; HGB: Haemoglobin; RBC: Red blood cells; WBC: White blood cells; PLT: Platelets; ESR: Erythrocyte sedimentation rate; CRP: C-reactive protein; ALT: Alanine aminotransferase; ASTA; Aspartate aminotransferase; CPKA; Creatine phosphokinase; LDH: Lactate dehydrogenase; RFA; Rheumatoid factor; GC: Glucocorticoids; MTX: Methotrexate; MMF: Mycophenolate mofetil; IVIG: Intravenous immunoglobulin.

Table 3 Capillaroscopic features of the studied groups, n (%)

Parameters	Active JDM (n = 26)	Inactive JDM (n = 23)	P value
Age at capillaroscopy, mean ± SD	9.7 (4.3)	11.4 (3.9)	0.156
Duration of disease before capillaroscopy, months, median (IQR)	36.0 (11.5, 52.5)	56.0 (15.0, 86.0)	0.161
Density average, n/mm, mean ± SD	3.6 (1.5)	6.3 (1.3)	< 0.001
Low density	25 (96.2)	14 (60.9)	0.003
Maximal arterial dimension, μm, median (IQR)	43.0 (29.6, 54.5)	21.6 (18.2, 25.7)	< 0.001
Maximal apical dimension, μm, median (IQR)	65.1 (46.6, 96.0)	31.9 (24.9, 40.3)	< 0.001
Maximal venous dimension, μm, median (IQR)	56.4 (39.6, 75.5)	26.3 (21.8, 37.0)	< 0.001
Dilated capillaries	26 (100.0)	22 (95.7)	0.469
Giant capillaries	19 (73.1)	3 (13.0)	< 0.001
Abnormal morphology	25 (96.2)	19 (82.6)	0.173
Microhaemorrhages	17 (65.4)	10 (43.5)	0.124
Perivascular extravasates	10 (38.5)	3 (13.0)	0.057
Perivasular edema	19 (73.1)	4 (17.4)	< 0.001

JDM: Juvenile dermatomyositis; IQR: Interquartile range.

Table 4 Correlations between capillaroscopic and skin features

Parameters	Low density	Dilated capillaries	Giant capillaries	Abnormal morphology	Microhaemorrhages	Perivascular extravasates	Perivasular edema
Erythema	0.40a	0.17	0.25	0.13	0.25	0.22	0.37a
Heliotrope rash	0.37a	0.14	0.47	0.05	0.19	-0.01	0.34a
Gottron papules	0.48a	0.20	0.49	0.18	0.20	0.15	0.51a
Raynaud’s syndrome	0.13	-0.29a	-0.05	0.17	0.15	0.04	0.23

^aP < 0.05.