Objective: To study the influence of clinical variables on improvement in muscle strength in patients with polymyositis and dermatomyositis.
Methods: We biomechanically examined muscle strength over the course of 2.54 years of 65 patients.
Results: Disease duration before therapy was predictive of outcome. Those treated within 6 months or one year of disease onset had better outcomes than those with later treatment. In addition, among those who gained strength, degree of elevation of creatine kinase was correlated with greater gains.
Conclusion: Early treatment after disease onset increases the chance of a favorable response.