FS 是一种罕见的类风湿关节炎的关节外表现,据估计,在 RA 患者中,发病率不足 1%。[5]Sibley JT, Haga M, Visram DA, et al. The clinical course of Felty's syndrome compared to matched controls. J Rheumatol. 1991;18:1163-1167.http://www.ncbi.nlm.nih.gov/pubmed/1941816?tool=bestpractice.com 很难确定其真实的发病率,因为许多受累患者无症状。另外,由于采用抗风湿药物 (DMARD) 和生物学治疗手段对 RA 疾病进行早期强化性抑制治疗,现在 FS 的发病率可能比以前更低,且表现更为轻微。[6]Almoallim H, Klinkhoff A. Longterm outcome of treatment of Felty's syndrome with intramuscular gold: case reports and recommendations for management. J Rheumatol. 2005;32:20-26.http://www.ncbi.nlm.nih.gov/pubmed/15630719?tool=bestpractice.com FS 往往发病于 50~79 岁,女性患者与男性患者的比率为 1.6:1.0。[2]Campion G, Maddison PJ, Goulding N, et al. The Felty syndrome: a case-matched study of clinical manifestations and outcome, serologic features, and immunogenetic associations. Medicine (Baltimore). 1990;69:69-80.http://www.ncbi.nlm.nih.gov/pubmed/1969604?tool=bestpractice.com 在儿童和黑人中罕见。[7]Rosenstein ED, Kramer N. Felty's and pseudo-Felty's syndromes. Semin Arthritis Rheum. 1991;21:129-142.http://www.ncbi.nlm.nih.gov/pubmed/1788550?tool=bestpractice.com HLA-DR4 抗原与 FS 密切相关,因此这些患者往往具有明确的 RA 家族史。[8]Balint GP, Balint PV. Felty's syndrome. Best Pract Res Clin Rheumatol. 2004;18:631-645.http://www.ncbi.nlm.nih.gov/pubmed/15454123?tool=bestpractice.com 在 FS 患者中,通常在出现中性粒细胞减少症之前的 10 至 20 年(平均而言)就有 RA 了。[2]Campion G, Maddison PJ, Goulding N, et al. The Felty syndrome: a case-matched study of clinical manifestations and outcome, serologic features, and immunogenetic associations. Medicine (Baltimore). 1990;69:69-80.http://www.ncbi.nlm.nih.gov/pubmed/1969604?tool=bestpractice.com