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Environmental risk factors in chronic, rheumatic muscle inflammation; myositis

The overall aim of this study is to investigate potential environmental risk factors for susceptibility to myositis.

The most common chronic inflammatory myopathies consist of polymyositis, dermatomyositis and sporadic inclusion body myositis, collectively called myositis. This is a rare group of disorders with an incidence of 10 cases/million population/year. Patients with myositis suffer primarily from skeletal muscle weakness and could potentially end up in a wheelchair.

Besides muscle inflammation and skin manifestations, lung involvement is also common in myositis and is a major cause of morbidity and mortality in polymyositis or dermatomyositis patients.

Although the etiology has not been clarified, available scientific data suggest that the interplay between genetic susceptibility and exposure to certain environmental factors is important. The most strongly associated genetic factor is HLA-DR3. However, no population based epidemiological studies have been made to identify particular environmental risk factor for myositis.


This project is a unique and nationwide population-based case-control study based on adult myositis patients that received the diagnosis myositis in Sweden during a three-year period. A questionnaire covering different exposures such as infections, smoking, UV-light, chemicals, pets, living- and working conditions was collected from 120 patients and 616 controls. The questionnaire used was based on a questionnaire employed in EIRA, a previous case-control study on rheumatoid arthritis (RA). The data will be analyzed with regard to the association between different exposures and risk of myositis.

Findings from this project may be a break-through in the myositis research area and have an impact on the understanding of disease mechanisms in chronic rheumatic muscle inflammation.

Project group

Professor Lars Alfredsson, Principal Investigator

Work: +46 8 524 87 488

Professor Ingrid Lundberg, Principal Investigator

Work:+46 8 517 76 087

Sevim Barbasso Helmers, PhD, Post doc

Work: +46 70 312 6975
Fax: +46 8 31 39 61