Table 14.
Characteristics of recently defined autoantibody phenotypes in juvenile myositis
| Characteristics | Anti-p155/140 | Anti-MJ | MSA/MAA Negative |
|---|---|---|---|
| Demographics | |||
| Median age at diagnosis (y) | Average (7.2 years) | Younger (6.2 years) | Average (7.9 years) |
| Race | Larger proportion white (80%) | Larger proportion white (72%) | No racial predilection |
| Severity of onset | Mild or moderate severity (76%) | Mild or moderate severity (68%) | Mild or moderate severity (72.9%) |
| Delay in diagnosis (mo) | Average delay (4.6 months) | Short delay (3.0 months) | Average delay (4.1 months) |
| Clinical group | JDM (JDM or JDM overlap) | Predominantly JDM (JDM or JDM overlap) | Predominantly JDM |
| Clinical Features | Gottron’s papules | Muscle cramps | Arthralgia |
| Malar rash | Dysphonia | Linear extensor erythema | |
| “Shawl-sign” rash | Contractures | Fever | |
| Photosensitivity | Gastrointestinal bleeding or ulcer | Gottron’s papules | |
| Cuticular overgrowth | Gottron’s papules | Arthritis | |
| Periungual capillary abnormalities | Malar rash | Gastrointestinal bleeding or ulcer | |
| Linear extensor erythema | Periungual capillary abnormalities | ||
| “V-sign” rash | Heliotrope rash | ||
| Cuticular overgrowth | Abnormal EKG or ECHO | ||
| Dysphagia | |||
| Heliotrope rash | |||
| Lipodystrophy | |||
| Erythroderma | |||
| Outcome | Muscle atrophy | Low mortality (1.3%) | |
| Low mortality (2.4%) | Monocyclic course (28%) | Monocyclic course (39%) | |
| Chronic disease course (65%) | Calcinosis (37%) | Calcinosis (37%) | |
| Hospitalized (63%) | |||
|
Intermediate frequency of wheelchair use
(24%) |
|||
| Laboratory Features |
Relatively lowest CK level (median 455
units/L) |
Intermediate CK level median (1563
units/L) |
Relatively lower CK levels (median 544 units/L) |
| High percentage ANA positive (84%) | High percentage ANA positive (64%) | ||
| Intermediate ANA titers (median 1:320) | Low positive ANA titer | Low positive ANA titer |
Abbreviations: MSA/MAA = myositis-specific and myositis-associated autoantibody; JDM = juvenile dermatomyositis; EKG = electrocardiogram; ECHO = echocardiogram; CK = creatine kinase; ANA = anti-nuclear antibody.
Bold = significant in logistic regression or universally present in the group; Italicized indicates top variables from random forest models. Other variables included in this table were significant in univariable analysis.