Polyserositis is an inflammatory condition involving different serosal membranes at the same time, specifically the pericardium, pleura, and peritoneum with exudates in the respective cavities. Treatment with non-steroidal anti-inflammatory drugs (NSAIDs), colchicine and glucocorticoids may be effective in patients with polyserositis, but relapses often occur when these drugs are tapered or discontinued. The interleukin (IL)-1 receptor antagonist anakinra has shown a beneficial effect in idiopathic recurrent pericarditis, mostly in unresponsive patients who develop steroid dependence and/or colchicine resistance. To date, there are no data suggesting the best therapy for managing acute episodes and/or relapses of polyserositis. On this basis, we performed a retrospective study aimed at evaluating the effectiveness and safety profile of anakinra in treating patients with refractory polyserositis.

Patients with idiopathic polyserositis or rheumatic diseases presenting inflammation of 2 or more serous membranes were included. Serositis had to be confirmed by imaging tests comprising either echocardiography, abdominal ultrasound, chest or abdomen computed tomography and/or chest x-ray scan. We included patients with polyserositis who started anakinra from January 2011 to January 2019 due to a poorly controlled disease despite treatment with NSAIDs, conventional immunosuppressant drugs, or the need to minimize oral corticosteroids intake. Erythrocyte sedimentation rate (ESR), C reactive protein (CRP), and imaging tests, were recorded to monitor serositis at baseline and either at 3, 6 and 12-month follow-up. Patients with malignancies and infectious diseases were excluded from the analysis.

Forty-five patients with recurrent polyserositis (23 women) (mean age 43.2±15.8 years and mean disease duration 23.1±28 years) were analysed. Polyserositis was idiopathic in 26 (57.8%) patients. Thirteen patients suffered from autoinflammatory diseases, whereas 6 were affected by autoimmune diseases. Combination treatment with colchicine and NSAIDs at anakinra baseline was administered in 38/45 (84.4%) and 37/45 (82.2%) patients, respectively. After starting anakinra, 84.5% of patients experienced a resolution of serositis with a dramatic decrease in ESR and CRP (P<0.001, for both) already at 3 months, furthermore the same beneficial effect was observed up to 12 months. No relapse was seen at 3 months, whereas the median number of relapses at 6 and 12 months was 0 (interquartile range 0-1). Glucocorticoids were discontinued in 22/45 (48.9%) patients already after 3 months (P<0.001). After 12 months 32/37 (86.5%) patients were steroid-free. Similarly, NSAIDs use significantly was decreased at 3 months (7/45 [15.6%] patients, P<0.001), whereas at 12-month follow-up no patient was on NSAIDs. Urticarial rashes at anakinra injection site occurring in 3 patients were the most common adverse events.

Anakinra appeared to be a safe and useful therapeutic choice for patients refractory to optimal anti-inflammatory therapy (NSAIDs, colchicine and corticosteroids), allowing not only a dramatic reduction of recurrences but also of corticosteroids use. Anakinra was effective both in the idiopathic forms of polyserositis and in those with an underlying rheumatic disease, suggesting a common pathogenic pathway leading to serositis onset.