A Study to Assess the Long-term Safety and Efficacy of a Subcutaneous Formulation of Efgartigimod in Adults With Active Idiopathic Inflammatory Myopathy

AE : adverse event ; SAE : serious adverse event ; AESI : adverse event of special interest.

The Composite Glucocorticoid Toxicity Index (C-GTI) serves as a primary instrument to capture toxicities likely caused by glucocorticoid exposure and enables monitoring of long-term tolerability of glucocorticoids during prolonged use. The Aggregate Improvement Score (AIS) is an analytical scores generated from the weighted C-GTI. The AIS can be used to assess whether a new therapy is effective in reducing glucocorticoid toxicity over time; higher AIS scores are associated with less toxicity.

The Composite Glucocorticoid Toxicity Index (C-GTI) serves as a primary instrument to capture toxicities likely caused by glucocorticoid exposure and enables monitoring of long-term tolerability of glucocorticoids during prolonged use. The Cumulative Worsening Score (CWS) is an analytical score generated from the weighted C-GTI. The CWS is designed to assess cumulative glucocorticoid toxicity; higher scores indicate increased steroid toxicity.

The Composite Glucocorticoid Toxicity Index (C-GTI) serves as a primary instrument to capture toxicities likely caused by glucocorticoid exposure and enables monitoring of long-term tolerability of glucocorticoids during prolonged use. The Glucocorticoid Toxicity Index-Metabolic Domains (GTI-MD) is an abbreviated GTI version limited to the 4 metabolic domains. A GTI-MD score of 0 indicates a low likelihood of toxicity in the assessed metabolic domains.

The total improvement score (TIS) assesses minimal, moderate, and major clinical response, and it is assessed using the ACR/EULAR criteria. The total score varies between 0 and 100, with higher scores indicating greater improvement.

The total improvement score (TIS) assesses minimal, moderate, and major clinical response, and it is assessed using the ACR/EULAR criteria. The total score varies between 0 and 100, with higher scores indicating greater improvement

The total improvement score (TIS) assesses minimal, moderate, and major clinical response, and it is assessed using the ACR/EULAR criteria. The ACR/EULAR criteria calculate TIS using the 6 core set measure (CSMs): MDGA, PGA, MMT8, HAQ-DI, muscle enzymes, and extramuscular global assessment (assessed by the MDAAT).

Clinically inactive disease is defined as no evidence of disease activity, based on an Physician Global Assessment of Disease Activity (MDGA) and Extramuscular Global Assessment of the Myositis Disease Activity Assessment Tool (MDAAT) of 0 and normal creatine kinase (CK) values for at least 12 weeks (at week 28 and every 24 weeks thereafter).

Remission is defined as a clinically inactive disease for at least 24 weeks

The Patient Global Impression of Severity (PGI-S) asks participants to rate the severity of their disease symptoms over the past 7 days on a 4-point Likert scale, where scores range from "no symptoms" to "severe."

The Clinical Global Impression of Severity (CGI-S) asks the physician to rate the severity of the participant's disease on a 4-point Likert scale, where scores range from "no activity" to "severe".

The 36-Item Short Form Survey version 2 (SF-36v2) is a 36-item scale constructed to survey health-related quality of life in 8 domains.

The EQ-5D-5L questionnaire is a standardized test recognized by many health authorities as a generic measure of health status for clinical and economic appraisal. The descriptive system comprises 5 dimensions, each having 5 levels ranging from "No problem" to "Extreme problem".

The EQ-5D-5L questionnaire is a standardized test recognized by many health authorities as a generic measure of health status for clinical and economic appraisal. A visual analog scale (VAS) is included in the EQ-5D-5L, where participants will mark their health status from 0 (the worst health you can imagine) to 100 (the best health you can imagine).

ADA : anti-drug antibodies.

Sustained low disease activity is defined as a CGI-S score of "mild" or "no activity" and a PGI-S score of "mild" or "no symptoms" for at least 12 weeks.

Low disease activity is defined as a CGI-S score of "mild" or "no activity" and a PGI-S score of "mild" or "no symptoms"

Low disease activity is defined as a CGI-S score of "mild" or "no activity" and a PGI-S score of "mild" or "no symptoms"

Marked worsening is defined as a CGI-S score of "moderate" or "severe" and a PGI-S score of "moderate" or "severe"