Table 1.
General features of adult myositis patients with and without AMA
| AMA-positive (N=30) % (n/N) or mean (SD) | AMA-negative (N=450) % (n/N) or mean (SD) | Univariate p-value | Multivariate p-value | Total (N=480) | |
|---|---|---|---|---|---|
| Female sex | 80% (24) | 61% (276) | 0.04 | 62% (300) | |
| Race | |||||
| White | 67% (20) | 75% (337) | 0.3 | 0.2 | 74% (357) |
| Black | 17% (5) | 18% (82) | 0.8 | 0.9 | 18% (87) |
| Other racesa | 17% (5)b | 7% (31) | 0.06 | 0.05 | 8% (36) |
| Age of onset (years) | 49.4 (14.9) | 52.9 (15.4) | 0.2 | 0.6 | 52.7 (15.4) |
| Follow-up time (years) | 3.4 (2.8) | 3.5 (3.4) | 0.9 | 0.4 | 3.4 (3.3) |
| Myositis autoantibody groups | |||||
| Anti-TIF1γ | 23% (7) | 10% (47) | 0.06 | 11% (54) | |
| Anti-NXP2 | 17% (5) | 8% (38) | 0.2 | 9% (43) | |
| Anti-MDA5 | 10% (3) | 5% (22) | 0.2 | 5% (25) | |
| Anti-Mi-2 | 10% (3) | 7% (31) | 0.5 | 7% (34) | |
| Anti-SRP | 3% (1) | 6% (27) | 1.0 | 6% (28) | |
| Anti-HMGCR | 10% (3) | 13% (60) | 0.8 | 13% (63) | |
| Anti-PL-12 | 3% (1) | 2% (11) | 0.5 | 2% (12) | |
| Anti-PL-7 | 0% (0) | 2% (10) | 1.0 | 2% (10) | |
| Anti-Jo-1 | 7% (2) | 13% (58) | 0.6 | 12% (60) | |
| Anti-Ro52 | 47% (14) | 29% (131) | 0.04 | 0.01 | 30% (145) |
| Myositis clinical groups | |||||
| IBM | 17% (5) | 32% (146) | 0.07 | 31% (151) | |
Dichotomous variables were expressed as percentage (count) and continuous variables as mean (SD). Univariate comparisons of continuous variables were made using Student’s t-test, while dichotomous variables were compared either using chi-squared test or Fisher’s exact test, as appropriate. Multivariate comparisons were performed using linear regression for continuous variables and logistic regression for dichotomous variables. All multivariate comparisons were adjusted by gender and clinical group (inclusion body myositis or autoantibody group)
aNon-Caucasian, non-African American, or unknown; bunknown: 3, Asian: 2
AMA anti-mitochondrial autoantibodies, TIF1 transcription intermediary factor 1, NXP2 nuclear matrix protein-2, MDA5 melanoma differentiation associated protein-5, SRP signal recognition particle, HMGCR 3-hydroxy-3-methylglutaryl-CoA reductase, IBM inclusion body myositis