Objective: To clarify the clinical characteristics of organizing pneumonia (OP) in rheumatoid arthritis (RA; RA-OP) and the association of OP development with RA exacerbation, and to identify OP recurrence predictors.
Methods: Data from 33 patients with RA-OP admitted to our hospital were retrospectively analyzed (2006-2016).
Results: RA onset preceded OP onset in 82% of patients, whereas OP onset preceded (OP-preceding) or co-occurred with RA in 9% of patients each. Median age at first OP onset was 64.0 years, and the period from RA onset to first OP onset was 5.5 years. At OP onset, 42% of events exhibited unilateral involvement and 76% had normal Krebs von den Lungen-6. RA disease control remained optimal in 52% of events and was exacerbated in 18% of events. Ten patients (30%) experienced OP recurrence with an interval of 13.0 months between events, and the first OP recurrence rate was 127/1000 person-years. Compared with nonrecurrent cases (n = 14), recurrent cases (n = 10) showed lower age at first OP onset (59.5 vs 67.1 yrs; P = 0.04) and a shorter period from RA onset to first OP onset (6.4 vs 14.2 yrs; P = 0.047); moreover, these cases included a higher number of OP-preceding patients (30% vs 0%; P = 0.03) and ever smokers (80% vs 36%; P = 0.03). OP-preceding patients showed shorter median recurrence-free survival time (15 vs 136 months; P = 0.01) and higher recurrence risk (hazard ratio 5.45; P = 0.02).
Conclusion: RA-OP showed a high recurrence rate and was not associated with RA exacerbation. Four RA-OP recurrence predictors were identified.
Keywords: disease attributes; interstitial lung diseases; recurrence; rheumatoid arthritis.
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