Influence of age on characteristics of polymyositis and dermatomyositis in adults

In a retrospective study of 79 consecutive patients, we evaluated characteristics of polymyositis (PM) and dermatomyositis (DM) and compared clinical presentation, biochemical findings, histologic changes, evolution, complications, and mortality rate of elderly patients (aged ≥65 yr) and younger patients (aged ≤64 yr) at the onset of PM/DM. We found a high prevalence of PM/DM in elderly patients: 23 patients (29%) were aged 65 years or over. We also found that esophageal involvement (34.8% versus 16.1%, respectively) and bacterial pneumonia related to both ventilatory insufficiency and esophageal impairment (21.7% versus 5.4%, respectively) were more common in elderly patients compared with younger patients, resulting in increased morbidity and mortality rates. Moreover, malignancy frequency was higher in elderly patients compared with younger patients (47.8% versus 9.1%, respectively, p = 0.0001), particularly patients with DM (10/11). Fifty percent of malignancies were colon malignancies in elderly patients. Erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and ferritin levels were also higher in the elderly patient group compared with the younger group, and the presence of serum hypoprotidemia, hypoalbuminemia, and anemia was more frequent. Finally, PM/DM complete remission was less frequent (13.6% versus 41.1%) and the mortality rate (47.8% versus 7.3%) was higher in elderly patients than in younger patients. The main causes of death in elderly patients were bacterial pneumonia, due to ventilatory insufficiency and esophageal impairment, and malignancies. Our findings therefore indicate that PM/DM-related esophageal and lung involvement should be systematically searched for in elderly patients. Esophageal manometry and pulmonary function tests should become an integral part of initial evaluation in elderly patients for early detection of impairment. Moreover, as we observed a marked overrepresentation of colon cancer in elderly patients with DM, we suggest that the search for malignancies in elderly patients with DM should include lower gastrointestinal tract investigations.