Myositis, Idiopathic inflammatory myopathies (IIM) Guideline

About this guideline

The idiopathic inflammatory myopathies (IIM), also known as myositis, comprise a heterogeneous group of inflammatory diseases affecting striated muscles, often resulting in muscle weakness. This guideline focuses on four of the most common IIM subtypes: dermatomyositis (DM, including juvenile DM), nonspecific/overlap myositis (which includes the anti-synthetase syndrome or ASS), immune-mediated necrotizing myopathy (IMNM), and inclusion-body myositis (IBM). Throughout this guideline, the term IIM refers to these subtypes unless otherwise specified. The document outlines diagnostic processes and treatment options.

Who is this guideline for?
This guideline is intended for all healthcare providers involved in the care of patients with IIM.

Patient information

IIM (“myositis”) is a group of muscle diseases encompassing various subtypes. Due to an abnormal immune response, muscles become inflamed and weakened. Myositis is often treatable to some extent, but treatment outcomes are not always optimal. A small percentage of patients recover fully, while the majority experience chronic symptoms.

How was this guideline developed?

The initiative for this guideline came from the Dutch Society of Neurology (NVN). It replaces the 2005 version. The updated guideline was developed by a multidisciplinary committee, including representatives from neurology, rheumatology, rehabilitation medicine, dermatology, pulmonology, pediatrics, pathology, and internal medicine. Patient perspectives were incorporated through contributions from the patient association Vereniging Spierziekten.

To promote international knowledge exchange on myositis, large portions of the guideline have been written in English.