Comparative Effectiveness of Azathioprine Versus Cyclosporine as an Initial Treatment for Idiopathic Inflammatory Myopathies: A Population-Based Observational Study.

OBJECTIVE: To compare the effectiveness of azathioprine (AZA) and cyclosporine (CsA) as initial treatments for patients with idiopathic inflammatory myopathies (IIM). METHODS: A retrospective cohort study was conducted using information from the National Health Insurance Service database of Republic of Korea. Patients with IIM who had started AZA or CsA as initial treatment between January 2007 and December 2011 were selected for the study. They were followed from the day of treatment initiation to the occurrence of study outcomes or the end of the study until December 2016. Effectiveness outcomes, defined as switching the drug or adding immunosuppressants, and discontinuation of corticosteroids, were compared between the two groups. The Cox proportional-hazards model was used to calculate the adjusted relative risk (aRR) with 95% confidence interval (CI) between the AZA and CsA groups. RESULTS: A total of 376 patients with incident IIM who used AZA (n = 288) or CsA (n = 88) were identified. The aRR of switching the drug or adding immunosuppressants (1.45 [95% CI 0.99-2.11]) was not significantly different between the CsA and AZA groups. Among patients who were treated with corticosteroids at baseline, the rate of discontinuation of corticosteroids was not different between the two groups (1.69 [95% CI 0.82-3.47]). CONCLUSIONS: The effectiveness of AZA and CsA as initial treatments for the management of IIM was comparable.

Temporal relationship between idiopathic inflammatory myopathies and malignancies and its mortality: a nationwide population-based study.

OBJECTIVES: To examine the temporal relationship between malignancies and idiopathic inflammatory myopathies (IIMs) and its impact on mortality. METHODS: A retrospective cohort for IIM patients was conducted using the Korean National Health Insurance Service databases. We observed more than 5 years before and after the diagnosis of IIM (2002~2016) to identify IIM patients who developed any malignancy and classified these patients into two groups: the cancer-associated myositis (CAM) group, who developed malignancy within 3 years before or after the diagnosis of IIM and the cancer-not-associated myositis (CNAM) group, who developed malignancy beyond 3 years of IIM onset. The survival rates of the two groups were compared. RESULTS: We identified 1072 incident cases of IIM between 2007 and 2011. A total 225 patients of these patients were diagnosed with malignancy. The development of malignancy was frequent within 1 year before and after the time of IIM diagnosis. The common sites of malignancies in the CAM group differed from those in the CNAM group: the lung, hematologic malignancy, and the liver were common in both groups, but thyroid and oropharynx followed them in CAM while prostate, stomach, breast, and thyroid followed them in CNAM. CAM patient mortality was worse compared with CNAM patients (log-rank test, p < 0.01). CONCLUSIONS: Among IIM patients with malignancy, common sites of malignancy were different between the CAM and CNAM groups, and patients with CAM had poor prognosis compared with CNAM patients. Key Points • The malignancies commonly occurred in incident idiopathic inflammatory myopathy (IIM) patients, especially within 1 year before and after the initial IIM diagnosis. • Patients with malignancy had poor survival compared with patients without malignancy. • Among the IIM patients with malignancy, patients who developed malignancy within 3 years of IIM diagnosis (cancer-associated myositis, or CAM, group) showed higher mortality than cancer-not-associated myositis, CNAM group. • We also found that the common types of malignancy were different between the CAM and CNAM groups.