Table 2.
Population of the area of residence and the presence of CADM or anti-MDA-5 antibodies
| CADM | α-MDA-5-positive | |||||||
|---|---|---|---|---|---|---|---|---|
| Population of area of residence (×1,000) | Total number of DM patients (M:F) | Mean age at onset (range) | Number (%) of patients (M:F) | P value* | Mean age at onset (range) | Number (%) of patients (M:F) | P value** | Mean age at onset (range) |
| T1 (0.5 to 108) | 31 (4:27) | 49.0 (4 to 70) | 16 (51.6%) (1:15) | P for difference = 0.096 | 47.3 (4 to 69) | 14 (45.2%) (1:13) | P for difference = 0.012 | 48.8 (20 to 66) |
| T2 (130 to 826) | 26 (7:19) | 44.0 (9 to 80) | 10 (38.5%) (3:7) | P for trend = 0.031 | 40.0 (9 to 59) | 7 (26.9%) (3:4) | P for trend = 0.003 | 39.9 (11 to 59) |
| T3 (2,200) | 38 (17:21) | 47.3 (1 to 79) | 10 (26.3%) (4:6) | 45.9 (1 to 73) | 5 (13.2%) (1:4) | 51.0 (39 to 63) | ||
CADM, clinically amyopathic dermatomyositis; DM, dermatomyositis; M:F, male:female; MDA-5, melanoma differentiation-associated gene 5. *Prevalence of CADM in total DM. **Prevalence of anti-MDA-5 in total DM.