Occult Lung Disease Shown a Hazard in Juvenile Dermatomyositis

Mathiesen PR, Buchvald F, Nielsen KG. Pulmonary function and autoantibodies in a long-term follow-up of juvenile dermatomyositis patients.Rheumatology (Oxford). Published online ahead of print, December 5, 2013.

Pulmonary dysfunction in juvenile dermatomyositis (JDM) patients needs to be identified at disease onset and repeatedly monitored, according to a 14-year study.

Although the disease is a rare complication of JDM, subclinical changes in lung function may occur early on, and active disease can lead to long-term damage, experts say.

The cross-sectional study of 51 JDM patients found 82% had normal lung function and 8% had restrictive interstitial lung disease (ILD) detected with spirometry testing.

The data were taken from 1976 to 2007 from the National Patient Register in Denmark.

While no patients reported pulmonary symptoms, the small group with JDM-related ILD and restricted spirometric pulmonary function showed increased long-term damage at follow-up (median 14.3 years) compared with those whose spirometry results were normal or obstructive. 

This means patients in the ILD group showed asymptomatic, limited lung capacity in spirometry testing as opposed to breathing impediments that could be reversed with a beta-2 (β-2) agonist inhaler, a rescue treatment often used in asthma.

The mean age at JDM onset was 7.7 years in the study group. Those found to have restrictive lung disease tended to be younger (14.2 years vs 21.7 years) with higher disease activity in skin, muscle symptoms, and damage in nine organ systems including the lungs.

The findings highlight the importance of repeat pulmonary function tests and imaging in JDM patients, the researchers says, adding that the lungs are affected in active disease, and subclinical pulmonary impairment appears linked to a more severe disease course. 

The study found no association between a restrictive pulmonary function test and JDM auto-antibodies.