LAUSR

Background Adult onset Still’s disease (AOSD) is a rare, auto-inflammatory disease that has unknown etiology and poorly defined pathogenesis. To date, there are several classification criteria, available for AOSD, but most commonly used one is proposed by Yamaguchi et al(.1 One of the major items of this set of criteria is leukocytosis with neutrophilia. Objectives To usefulness of solely neutrophilia instead of leukocytosis with neutrophilia for the Yamaguchi criteria. Methods Sixty-one AOSD patients followed at Hacettepe University department of rheumatology were included to analysis. Diagnosis of AOSD was based on physicians’ decision, but Yamaguchi criteria was applied for all patients, as well. Complete blood test with differential was noted at the time of diagnosis of AOSD. One of the major criteria of Yamaguchi criteria was ‘’leukocytosis with neutrophilia (defined as more than 80% of leukocytes would be granulocyte)’’. Leukocytosis [(>10000/mm3) x1000] and neutrophilia [(6400/mm3) x1000] were defined according to normal upper limits of our laboratory. To compare with Yamaguchi criteria, neutrophil/leukocyte ratio for all patients were calculated. Descriptive statistics for non-normally distributed countable data were given as median and interquartile range (Med [IQR]). p<0,05 was considered as statistically significant. Results Total 61 patients (46 (75%) female) were recruited. Prevalence of major and minor Yamaguchi criteria were as follow: fever in all patients, arthralgia in 58 (95%) patients, rash in 43 (71%) patients, sore throat in 48 (79%) patients, lymphadenopathy and/or splenomegaly in 23 (38%) patients, absence of RF and ANA in 58 (96%) patients, elevated liver enzymes in 47 (77%) patients. Median leukocyte and neutrophil count were 13.5 (IQR;10.1–18,9) x 1000/mm3, 12 (IQR;7.2–17.6) x 1000/mm3, respectively. ‘’Neutrophilia >UNL’’ was significantly more prevalent than ‘’leukocytosis with neutrophilia >80%’’ (51 (83,6%) vs. 37 (60,6%), p<0,001). Overall, 14 (23%) patients would have one more positive major criteria if ‘’neutrophilia >UNL’’ would be used instead of ‘’leukocytosis with neutrophilia >80%’’. When current Yamaguchi criteria (including leukocytosis with neutrophilia >80%) applied to patients with AOSD, 57 (93,5%) of 61 patients were met the criteria. However, when ‘’neutrophilia >UNL’’ was used instead of ‘’ leukocytosis with neutrophilia >80%’’, all patients were met the revised criteria. Conclusions As all patients who had leukocytosis also had neutrophilia but it was not vice versa. In other words, choosing ‘’ leukocytosis with neutrophilia >80%’’ instead of ‘’neutrophilia >UNL’’ can underdiagnose AOSD approximately in%7 of patients according to Yamaguchi criteria. Moreover, Physicians should be keep in mind that reactive hemophagocytosis may influence the count of leukocyte. Consequently, using ‘’neutrophilia >UNL’’ as a criteria instead of ‘’leukocytosis with neutrophilia >80’’ may be more appropriate for the diagnosis of AOSD in real life. Reference [1] Yamaguchi M, Ohta A, Tsunematsu T, Kasukawa R, Mizushima Y, et al. Preliminary criteria for classification of adult Still’s disease. J Rheumatol1992;19:424–30. Disclosure of Interest None declared