American rheumatologists have investigated myositis complicated by interstitial lung disease, focusing in particular on the predictive value of respiratory function measurements over time:
- a cohort of 149 adults (median age 50 years) was established at a single US centre,
- comprising mainly patients being monitored for an antisynthetase syndrome (73%),
- respiratory function tests were carried out at various intervals, measuring vital capacity and carbon monoxide diffusion capacity (DLCO),
- a decline in vital capacity (estimated at 5% or more) during the first year of the disease course was found to be predictive of a poor prognosis (mortality or the need for lung transplantation),
- however, changes in DLCO over the first year had no predictive value.
These findings support the need for increased and regular monitoring during the first year of the course of myositis with interstitial lung disease.
