Clinical characteristics and genetic analyses of 187 patients with undifferentiated recurrent fever

Objectives: To describe the clinical characteristics, treatment response and genetic findings in the largest cohort of patients with syndrome of undifferentiated recurrent fever (SURF). Methods: Clinical and genetic data from patients with SURF were extracted from the Eurofever registry, an international web-based registry that retrospectively collects clinical information on patients with autoinflammatory diseases. Results: In this study 202 patients were included. Seven patients had a chronic disease course, 195 patients had a recurrent disease course. The median age at disease onset was 4.6 years. Patients had a median of 12 episodes per year, with a median duration of 4 days. In 25 patients relatives were affected as well. Most commonly reported symptoms were arthralgia (n=125), myalgia (n=95), abdominal pain (n=98), fatigue (n=120), malaise (n=112), and mucocutaneous manifestations (n=139). In 17 patients genetic variants were found in autoinflammatory genes. These patients more often had affected relatives compared to patients without genetic variants (p=0.002). Most patients responded well to NSAIDs, corticosteroids, colchicine and anakinra. Complete remission was rarely achieved with NSAIDs alone. Notable patterns were found in patients with distinctive symptoms. Patients with pericarditis (n=12) were older at disease onset (32.3 years), and had fewer episodes per year (3.0/year) compared to other patients. Patients with an intellectual impairment (n=8) were younger at disease onset (2.2 years) and often had relatives affected (28.6%). Conclusion: This study describes the clinical characteristics in the largest cohort of SURF patients. Patients with genetic variants found more often had relatives affected.