Which factors predict recurrence of RA-related organizing pneumonia?

The recurrence rate of organizing pneumonia (OP) associated with rheumatoid arthritis (RA) is high, but OP does not appear to contribute to RA exacerbation, suggests a study. Several factors predicting OP recurrence have been identified, such as smoking and lower age at OP onset.

Data from 33 RA-OP patients admitted to a hospital were retrospectively analysed from 2006 to 2016 to determine the clinical characteristics of RA-OP, to confirm whether OP development correlated with RA exacerbation, and to pinpoint predictors of OP recurrence.

Of the patients, 82 percent had RA onset prior to OP onset, whereas 18 percent had OP onset preceding (OP preceding) or co-occurring with RA (9 percent each). Median age at first OP onset was 64.0 years, and the time to first OP onset from RA onset was 5.5 years.

Forty-two percent of events had unilateral involvement and 76 percent had normal Krebs von den Lungen-6 at OP onset. Disease control of RA was favourable in 52 percent of events but was exacerbated in 18 percent. OP recurrence occurred in 10 patients (30 percent), with an interval of 13.0 months between events. Additionally, the rate of first OP recurrence was 127 per 1,000 person-years.

Patients with OP recurrence (n=10), compared to those with nonrecurrence (n=14), had lower age at first OP onset (59.5 vs 67.1 years; p=0.04), a shorter period from RA onset to first OP onset (6.4 vs 14.2 years; p=0.047), were more likely to be OP-preceding (30 percent vs 0 percent; p=0.03), and were ever smokers (80 percent vs 36 percent; p=0.03).

Moreover, OP-preceding patients had a shorter median recurrence-free survival (15 vs 136 months; p=0.01) and a higher risk of recurrence (hazard ratio, 5.45; p=0.02).