Myositis
Abstract Number 1242 - Adult Clinical Amyopathic Dermatomyositis with Rapid Progressive Interstitial Lung Disease: A Retrospective Study
AUTHORS: shuang ye, wenqun Huang, meifang wu, yun deng, chengde Yang, yueying Gu, chunde Bao, shunle Chen. Renji Hospital, Shanghai, China
PURPOSE: To investigate the characteristics of adult clinical amyopathic dermatomyositis (CADM) with rapid progressive interstitial lung disease (ILD), a fatal subtype of dermatomyositis (DM).
METHODS: Retrospectively studied DM and polymyositis (PM) patients between 1998 and 2005 in Shanghai Renji hospital. Two hundred and two adult patients with idiopathic inflammatory myopathy were studied and classified into CADM according to a modified Sontheimer’s definition, in addition to classic DM and PM group. They were further stratified based on the presence or absence of clinical ILD (Table 1).
Table 1. 202 patients with adult idiopathic DM/PM |
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| CADM | CADM | DM | DM | PM | PM | |
| ILD + | ILD - | ILD + | ILD - | ILD + | ILD - | |
| No. of patients ( female) | 26(16) | 11(8) | 36(20) | 46(32) | 24(19) | 59(40) |
| Age of onset of disease-year | 51±9 | 45±13 | 47±12 | 52±15 | 50±21 | 44±15 |
| Muscle strength0-5 grade | 4.9±0.2 | 5±0 | 4.1±0.7 | 3.6±1.0 | 4.3±0.9 | 3.9±0.9 |
| creatine kinase normal<190u/L |
96 ±118 |
105 ±82 |
1218 ±2208 |
2787 ±5024 |
2628 ±2455 |
2986 ±2702 |
| ANA(Jo-1) positive /detected No. | 6/24 | 2/9 | 11/32 | 11/37 | 13(5)/22 | 17/50 |
| No. of deceased | 12 | 0 | 12 | 5 | 6 | 1 |
| No. of drop out in follow-up | 5 | 4 | 8 | 18 | 3 | 19 |
Kaplan-Meier survival analysis and COX regression were performed. Predictive factors for ILD were also studied by Logistic regression. Clinical properties of CADM-ILD were explored.
RESULTS: The presence of clinical ILD was a significant risk factor for poor outcome of DM/PM (OR=4.237,CI 95%: 1.239 to 14.49, p=0.021). Presence of rash (OR=2.905, CI95%: 1.498 to 5.632, p=0.002) and elevated BUN (OR=1.067, CI95%: 1.020 to 1.116, p=0.004) are other independent risk factors of DM/PM survival. CADM, DM, and PM complicated by ILD had different clinical courses. CADM-ILD showed a rapid progressive pattern. The six-month cumulative survival rate for CADM-ILD was only 40.8%, while DM-ILD manifested a sub-rapid progressive pattern, with a 5-year survival rate of 54%. PM-ILD was a chronic process with a 5- and 10-year survival rate of 72.4% and 60.3%, respectively (Figure 1).
Muscle strength and ESR were positively correlated, while serum albumin negatively correlated with ILD in DM/PM. Those with CADM-ILD who died were refractory to conventional treatment and tended to have lower PO2. The presence of ANA was protective.
CONCLUSION: ILD is a common complication and a prominent prognostic indicator of DM/PM. Not uncommonly seen in Asian populations, CADM-ILD is a special phenotype, often rapid progressive and fatal.
COMMENT: This study reiterates the importance of recognizing ILD- related to clinically amyopathic dermatomyositis. Initially, malignancy and interstitial lung disease were under-recognized in this population – thought to represent a less severe disease subset. This study demonstrates the difference in survival curves in various myositis populations and highlights the increased mortality in the CADM-ILD subset. Perhaps, surrogate markers such as elevated ESR or a negative ANA may be helpful in predicting which patients with DM (with or without clinical or biochemical evidence of myositis) or PM have or will develop ILD. These findings have implications for clinicians caring for these patients, and serves to increase awareness of the disease severity in this patient population.
