The presence of an underlying malignancy was associated with a higher mortality rate.
Unfavorable prognostic factors found to be independent:
(1) older age (> 60 years)
(2) fever (> 38°C)
(3) leukocytosis (> 10,000 per µL) at diagnosis
(4) failure to achieve a clinical remission
Unfavorable prognostic factors of borderline significance:
(5) shorter disease history (< 7 months between onset and diagnosis)
(6) dysphagia
Most common causes of death in patients:
(1) malignancy
(2) pulmonary complications
(3) ischemic heart disease
(4) uremia
Factors found not to have prognostic significance:
(1) history and physical examination: arthritis, Raynaud's phenomenon, blood pressure, splenomegaly, gender
(2) electrophysiologic measures: EMG abnormalities, ECG abnormalities
(3) laboratory findings: ESR, ANA, abnormal muscle histopathology, hemoglobin, level of muscle enzymes
