Background The initial symptoms of Adult-onset Still Disease (AOSD) are non-specific and confusing with those of common cold, which can lead to the delay of diagnosis and treatment.

Objectives To clarify characteristic features in AOSD in very early phase and to find the key symptoms and markers to an earlier diagnosis and treatment.

Methods We retrospectively reviewed consecutive AOSD patients in our hospital from April 2012 to July 2017. Symptoms and laboratory data before treatment were collected form their charts and analysed.

Results A total of 62 patients were enrolled. The mean age at diagnosis was 45.9 and female was 81%. The duration from the first symptoms to the first visit to a medical facility was 18.7 days, from the first visit to the first blood test was 5.8 days, from the first blood test to the fulfilment of Yamaguchi’s Criteria was 11.0 days, and from the fulfilment of Yamaguchi’s Criteria to the treatment was 22.2 days. During the course of developing the disease, fever was found in all patients, skin lesion in 91.9%, arthralgia in 87.1%, sore throat in 66.1%. Laboratory and imaging tests demonstrated liver enzyme elevation in 82.2%, white blood cell count (WBC) increase in 80.6%, lymphadenopathy/splenomegaly in 72.6%, negative RF and ANA in 56.5%, ferritin elevation in 82.3%. Laboratory tests before treatment demonstrated that the mean WBC count 15272.3/μL, AST 101.8 U/L, CRP 15.1 mg/dl, and ferritin 10103.1 ng/ml. Patients who presented with sore throat as the first symptom fulfilled Yamaguchi’s Criteria in 13.6 days after the onset, which was shorter than patients with any other symptoms (fever, 24.0 days; arthralgia, 45.7 days; skin lesion, 31.5 days). Before treatment, patients with sore throat as the first symptom showed highest AST of 139.6 U/L (fever, 95.3 U/L; arthralgia, 100.7 U/L; skin lesion, 71.6 U/L) and highest ferritin of 19791.8 ng/ml (fever, 9508.2 ng/ml; arthralgia, 13071.5 ng/ml; skin lesion, 8438.1 ng/ml). However, the duration from the Yamaguchi’s Criteria fulfilment to treatment initiation in patients with sore throat as the first symptom was 38.5 days, which was no less than that in patients with the other symptoms (fever, 15.4 days; arthralgia, 31.0 days; skin lesion, 27.0 days).

Conclusions Although symptoms of AOSD developed rapidly with symptoms of sore throat, fever, liver enzyme elevation and ferritin elevation, the diagnosis was frequently delayed. Our study suggests that the delayed diagnosis can be attributed in part to non-assumption of the disease. Paying attention to the combination of these symptoms can lead to an earlier diagnosis.

Disclosure of Interest None declared