Acute exacerbations (AEs) are both common in rheumatoid arthritis–associated interstitial lung disease (RA-ILD) and are a frequent cause of imminent mortality, a retrospective Japanese study suggests.
The same is also true for patients with idiopathic pulmonary fibrosis (IPF) for whom an AE is the most frequent cause of death as well, the same comparative study indicates.
“Several studies have reported that acute exacerbation, which occurs during the clinical course of idiopathic pulmonary fibrosis (IPF), also occurs in rheumatoid arthritis–associated interstitial lung disease (RA-ILD),” lead author Junji Otsuka, MD, PhD, of the National Hospital Organization Omuta National Hospital, Fukuoka, Japan, and colleagues observed.
“[We found that] AE was not uncommon in RA-ILD or IPF ... but the prognosis after AE of RA-ILD was significantly better than that of IPF [even though] the most frequent cause of death in RA-ILD and IPF was AE,” they stated.
The study was published online in Respiratory Medicine.
Patient features
The study involved 149 RA-ILD patients with a median age of 72 years at RA onset. The median time from ILD diagnosis to onset of AE was 48.5 months, while the median survival time after the onset of AE was 196 days (range 1-3,463 days), as the authors detailed. “All patients were treated with corticosteroids,” the authors noted, and almost all of them were treated with steroid pulse therapy.
Noninvasive positive pressure ventilation (NPPV) was used to maintain oxygenation in 18.5% of patients with severe respiratory failure, while invasive positive pressure ventilation (IPPV) was used in almost 26% of patients with the same degree of respiratory failure. Features of patients who developed an AE were then compared with those who did not.
Interestingly, no significant differences in clinical parameters were seen between those who developed an AE and those who did not. Nor were there any significant differences between the 2 groups in the length of time from the ILD diagnosis to the development of an AE. Some 18% of RA-ILD patients developed an AE, as did over 27% of patients with IPF, investigators report.
, compared with only 60 days for those with IPF (P = .038). In a multivariable analysis, hypoalbuminemia at an odds ratio of .090 (95% confidence interval, 0.011-0.733; P = .012) as well as percent carbon monoxide diffusion capacity at an OR of .810 (95% CI, 0.814-0.964; P < .01) were both independent risk factors for the development of an AE, the investigators pointed out.
The best cut-off level for predicting the risk of an AE was 3.0 g/dL (95% CI, 0.011-0.733; P = .012) for serum albumin and 53% (95% CI, 0.814-0.964; P < .01) for carbon monoxide diffusion capacity. As Dr. Otsuka noted in an email to this news organization, low serum albumin likely correlates with a generally poor condition, while low carbon monoxide diffusion capacity is likely due to lung fibrosis.
“But if low albumin and low carbon monoxide diffusion capacity are due to the progression of ILD, both values may be difficult to improve,” he added.