Background Idiopathic thrombocytopenic purpura (ITP) may play a role in early-stage systemic lupus erythematosus (SLE). The incidence of SLE in patients with ITP and the potential relationship between them is still unclear. This study was performed to provide epidemiological evidence regarding the relationship between ITP and SLE occurrence. Methods In this population-based retrospective cohort study, the risk of SLE was analysed in a cohort of patients newly diagnosed with ITP between 2000 and 2013. Controls were selected at a 1:2 ratio through propensity score matching (PSM) using the greedy algorithm. The Cox proportional hazard model was used to analyse the association between ITP and SLE incidence. There were four different Cox regression models, and the sensitivity analyses were implemented to evaluate the HR of SLE after exposure with ITP. Results In the age-matched and sex-matched ITP and non-ITP cohort, the average follow-up time was about 80 months in this study. There were 34 (4.70%) and 27 (0.19%) incident cases of SLE in ITP and non-ITP group. The incidence rates were 62.0 (95% CI 44.3 to 86.8) and 2.10 (95% CI 1.44 to 3.06), respectively. The adjusted HR of incidental SLE in the ITP group was 25.1 (95% CI 13.7 to 46.0). The other risk factors for SLE were female sex and Sjogren’s syndrome. After PSM, the incidence rate and Kaplan-Meir curves of SLE were consistent with the results for the age-matched and sex-matched population, the HR 17.4 (95% CI 5.28 to 57.4) was estimated by conditional Cox model. Conclusion This cohort study demonstrated that patients with ITP have a higher risk of SLE. Clinically, patients with ITP should be monitored for incidental lupus.

中文翻译：

---

特发性血小板减少性紫癜患者患系统性红斑狼疮的风险：一项基于人群的队列研究

背景特发性血小板减少性紫癜（ITP）可能在早期系统性红斑狼疮（SLE）中发挥作用。ITP 患者 SLE 的发生率及其之间的潜在关系尚不清楚。本研究旨在提供有关 ITP 与 SLE 发生之间关系的流行病学证据。方法 在这项基于人群的回顾性队列研究中，对 2000 年至 2013 年间新诊断的 ITP 患者的 SLE 风险进行了分析。使用贪心算法通过倾向评分匹配 (PSM) 以 1:2 的比例选择对照。Cox比例风险模型用于分析ITP与SLE发病率之间的关联。有四种不同的Cox回归模型，并进行敏感性分析来评估ITP暴露后SLE的HR。结果 在本研究中，年龄匹配和性别匹配的 ITP 和非 ITP 队列中，平均随访时间约为 80 个月。ITP组和非ITP组分别有34例（4.70%）和27例（0.19%）发生SLE病例。发病率分别为 62.0（95% CI 44.3 至 86.8）和 2.10（95% CI 1.44 至 3.06）。ITP 组偶发 SLE 的调整后 HR 为 25.1（95% CI 13.7 至 46.0）。系统性红斑狼疮的其他危险因素是女性和干燥综合征。PSM后，SLE的发病率和Kaplan-Meir曲线与年龄匹配和性别匹配人群的结果一致，通过条件Cox模型估计HR 17.4（95% CI 5.28至57.4）。结论 该队列研究表明，ITP 患者患 SLE 的风险较高。临床上，应监测 ITP 患者是否患有偶发性狼疮。