What is Known and Objective: Allopurinol-induced drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare but serious and potentially life-threatening drug hypersensitivity syndrome. In this study, we aimed to investigate the clinical features, treatment outcomes, and prognostic factors of allopurinol-induced DRESS.Methods: Case reports of allopurinol-induced DRESS published by China from January 2000 to August 2021 were retrieved from CNKI, Wan Fang, VIP, and PubMed databases for analysis.Results and Discussion: This study included 52 patients, consisting of 41 (78.8%) males and 11 (21.2%) females (M:F = 3.7:1). The mean of age was 56.1 ± 17.1 years (range: 18-86 years). The mean of latency periods was 24.6 ± 15.0 days (range:1-63 days). Most patients presented with fever, cutaneous eruption, eosinophilia, lymphadenopathy, and facial edema. 36/52 (69.2%) patients showed two or more internal organs involved. Liver and kidney injuries were the most common visceral manifestation. Pulmonary involvement (34.6%), cardiac involvement (25.0%) and gastrointestinal involvement (21.2%) were relatively less known but severe complications. 2/52 (3.8%) patients showed nervous system involved, presenting as leukoencephalopathy or peripheral neuropathy. 2/52 (3.8%) patients presented with secondary hemophagocytic lymphohistiocytosis.1/52 (1.9%) patient developed pure red cell aplasia and 1/52 (1.9%) patient developed painless thyroiditis. HLA*B 58:01 allele was tested in 18/52 (34.6%) patients. 16/18 (88.9%) cases were positive. 48/ 52 (92.3%) patients were treated with systemic corticosteroids. 16/52 (30.8%) patients were cured, 23/52 (44.2%) patients received partial recovery, and 13/52 (25.0%) patients were died. Septic shock, gastrointestinal bleeding and multiple organ failure were the leading causes of death. Advanced age, underlying cardiovascular disease, chronic kidney disease and high dose of allopurinol, infection and internal organ involvement (including kidney, heart, lung and gastrointestinal tract) were risk factors for death. What is New and Conclusion: We explored clinical features, treatment outcomes and prognostic factors of 52 allopurinol-induced DRESS cases in China. Ethnicity, especially Han Chinese, and positive HLA-B*58:01 allele are the clearest risk factors so far. Advanced age, underlying cardiovascular disease, chronic kidney disease and high dose of allopurinol, infection and internal organ involvement (including kidney, heart, lung and gastrointestinal tract) were associated with poorer outcomes. Early

BACKGROUND AND AIMS Allopurinol is the first-line prescribed agent for hyperuricemia and gout. Allopurinol-induced drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare but serious and potentially life-threatening drug hypersensitivity syndrome. This study aimed to investigate the clinical features, treatment, outcome and prognostic factors of allopurinol-induced DRESS. METHOD Case reports of allopurinol-induced DRESS published by China from January 2000 to August 2021 were retrieved from CNKI, Wan Fang, Wei Pu and PubMed databases for analysis. RESULTS This study included 46 patients, consisting of 34 (73.9%) males and 12 (26.1%) females (M: F = 2.8:1). The mean of age was 56.1 ± 17.4 years (range: 23–86 years). The mean of latency periods was 24.0 ± 14.8 days (range:1–60 days). Most patients presented with fever, cutaneous eruption, eosinophilia, lymphadenopathy and facial oedema. All patients showed at least one internal organ injury. A total of 35/46 (76.1%) patients showed two or more internal organs involved. Liver and kidney injury were the most common visceral manifestations. One patient showed central nervous system involved, presenting as leukoencephalopathy. HLA*B 58:01 allele was tested in 19/46 (41.3%) patients. A total of 18/19 (94.7%) patients were positive. A total of 45/46 (97.8%) patients were treated with systemic corticosteroids. Patient outcomes were known for 45 of the 46 patients. A total of 13 (28.9%) patients were cured, 24 (53.3%) patients received partial recovery and 8 (17.8%) patients died. Septic shock and multiple organ failure were the leading causes of death. Patients with older age, underlying cardiovascular disease, chronic kidney disease, infection and internal organ involvement (including kidney, heart and lung) were associated with poorer outcomes. CONCLUSION We explored clinical features, treatment, outcome and prognostic factors of 46 allopurinol-induced DRESS cases in China. Early identification and discontinuation of the causative drug are crucial to the management of DRESS. For patients with severe disease, corticosteroids are recommended as the first-line therapy. However, further studies are needed to address diagnostic criteria of DRESS for early diagnosis, as well as to develop standardized corticosteroid treatment regimens.