The change of 3 isometric strengths and creatine kinase in serum in patients with stable polymyositis

Purpose: The aim of this study was to examine the usefulness of 3 isometric strengths (sum) in patients with polymyositis (PM) not only in the acute phase but also in the stable stage. Subjects: Our subjects were five females (average age 36.2) with PM. Methods: We traced the change in three isometric strengths (head up, HU; shoulder abduction; straight leg raising) measured by a hand-held dynamometer, creatine kinase level in serum (CK) and prednisone (PSL) dosage for more than 30 weeks. Results: The change of the sum of 3 isometric strengths was correlated to CK in four patients, however, the correlation coefficient value was low. The individual strength of HU was also correlated to CK in four patients. Furthermore, HU was negatively correlated to PSL dosage in four patients though the sum strength was correlated in only three of five patients. Conclusion: These results suggest that sequential measurement of the sum of isometric strengths would be effective for predicting the disease progress in the stable stage, though, not as much as in the acute phase. Sequential measurement of HU might be more effective for identifying the CK level or drug effect in stable stage.