Multivariate analysis of the extent of the different thigh MRI features (percentage of muscles involved) among different clinical subsets using fractional probit regression
| Oedema | Atrophy | Fatty replacement | Fascial oedema | |
|---|---|---|---|---|
| dy/dx (95% CI) | dy/dx (95% CI) | dy/dx (95% CI) | dy/dx (95% CI) | |
| Clinical subset (referenced to IMNM) | ||||
| IBM | −5.82 (−13.31 to 1.66) | 0.92 (−4.23 to 6.06) | 1.52 (−5.56 to 8.61) | 1.68 (−3.87 to 7.23) |
| PM | −23.72 (−30.63 to −16.80)*** | −10.92 (−16.38 to −5.46)*** | −10.77 (−17.69 to −3.86)** | 0.05 (−4.53 to 4.64) |
| DM | −22.14 (−29.36 to −14.93)*** | −18.24 (−24.00 to −12.47)*** | −17.39 (−24.21 to −10.57)*** | 8.82 (4.53 to 13.11)*** |
| CADM | −61.46 (−85.87 to −37.05)*** | −25.76 (−39.13 to −12.39)*** | −31.18 (−46.55 to −15.80)*** | 1.85 (−6.86 to 10.57) |
| Age at onset (10 years) | 0.73 (−1.10 to 2.56) | 2.41 (0.84 to 3.97)** | 2.05 (0.34 to 3.77)* | −0.88 (−1.76 to 0.00) |
| Time from onset to MRI (logarithm of months) | −8.83 (−14.34 to −3.33)** | 10.44 (6.13 to 14.74)*** | 13.90 (8.90 to 18.89)*** | −4.82 (−7.39 to −2.26)*** |
| Sex (female) | −9.60 (−14.58 to −4.61)*** | 3.24 (−0.45 to 6.92) | −8.61 (−13.11 to −4.11)*** | −2.92 (−5.72 to −0.11)* |
| Race (referenced to white patients) | ||||
| Black | 6.11 (−1.70 to 13.92) | 0.84 (−5.26 to 6.95) | 8.18 (1.59 to 14.77)* | −0.49 (−4.77 to 3.80) |
| Other races | 2.26 (−5.86 to 10.37) | 4.08 (−1.70 to 9.86) | −0.02 (−7.69 to 7.66) | −0.51 (−4.74 to 3.73) |
dy/dx, marginal effect (% change of the dependent variable for each one point of the predictor variables).
*<0.05; **<0.01; ***<0.001.
CADM, clinically amyopathic dermatomyositis; DM, dermatomyositis; IBM, inclusion body myositis; IMNM, immune-mediated necrotising myopathy; PM, polymyositis.