Background Perianal Crohn's disease(PCD) significantly impacts quality of life with poor long-term prognosis. Anti-tumor necrosis factor(anti-TNF) therapy improves fistula closure rates. However, achieving permanent closure remains challenging. Our aim is to evaluate the relation between antiTNF(infliximab (IFX) and adalimumab(ADA) serum concentrations at induction(w2 and 6), and clinical and radiological outcomes at w24 and w52 Methods We conducted a single tertiary center, retrospective, cohort study including patients with an established diagnosis of PCD treated with antiTNF because of perianal activity. Variables related to their PCD(phenotype, location, fistulas type) were collected. Regarding treatment, we collected serum levels at week 2,6,24 and 52, concomitant treatment and setons presence. We defined clinical response as the absence of drainage on physical examination and clinical remission as the absence of external fistula openings. Radiological response was defined as the absence of T2 hypersignal, gadolinium enhancement, abscess and proctitis in pelvic MRI Results 65 patients were included, baseline characteristics are in Table1. None of the demographic characteristics collected were statistically significant related to clinical or radiological response although non smokers(p=0.01), ileal(p=0.02) and non-stricturing disease(p=0.01) had statistically significant higher drug levels. Taking into account the clinical response at w52, IFX mean levels at w2 were 25.8µg/mL(SD 4.1) in non responders and 30.9µg/mL(SD 14) in responders(p=0.39). At w6 they were 17.2µg/mL(SD 12.2) and 19.4µg/mL(SD 13.8) respectively(p=0.7). ADA mean levels at w2 were 13.3µg/mL(SD 7.7) in non responders and 14µg/mL(SD 6.3) in responders(p=0.87). At w6 they were 10.1µg/mL(SD 3.3) and 12µg/mL(SD 6.1) respectively(p= 0.59). For radiological response at w52 IFX mean levels at w2 were 27µg/mL(SD 15.3) in non responders and 32.7µg/mL(SD 14.5) in responders(p=0.45). At w6 the mean levels were 15.9µg/mL(SD 6.7) and 23.7µg/mL(SD 14.8) respectively(p=0.27). In ADA group the mean levels at w2 were 14.8µg/mL(SD 7.6) in responders and only one patient did not respond. At w6 ADA mean levels were 12.3µg/mL(SD 5.9) in non responders and 12.7µg/mL(SD 6.2) in responders(p=0.94). Early response at w24 was related with a long-term response at w52, 89.9% of the patients who responded at w52, had already responded at w24. Conclusion In our study we observed that almost 90% of the patients who had an early response also responded at w52, so trying to achieve an early response should be an aim in clinical practice. Despite the limited number of patients, our study shows a trend in the relationship between higher antiTNF levels and clinical and radiological response rates

中文翻译：

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P611 肛周克罗恩病诱导期间抗TNF水平与临床和放射学结果之间的关系

背景 肛周克罗恩病（PCD）显着影响生活质量，且长期预后不良。抗肿瘤坏死因子（抗TNF）治疗可提高瘘管闭合率。然而，实现永久关闭仍然具有挑战性。我们的目的是评估诱导时（第 2 周和第 6 周）抗 TNF（英夫利昔单抗 (IFX) 和阿达木单抗 (ADA)）血清浓度与第 24 周和第 52 周临床和放射学结果之间的关系。 方法 我们进行了一项单三级中心回顾性队列研究包括因肛周活动而确诊为 PCD 并接受抗TNF治疗的患者。收集了与其 PCD 相关的变量（表型、位置、瘘管类型）。关于治疗，我们收集了第 2、6、24 和 52 周的血清水平，同时治疗和挂线存在。我们将临床反应定义为体检时没有引流，临床缓解定义为没有外瘘开口。放射学反应定义为盆腔 MRI 结果中没有 T2 高信号、钆增强、脓肿和直肠炎。65尽管非吸烟者（p = 0.01），回肠（p = 0.02）和非狭窄性疾病（p = 0.01），但收集的人口统计学特征与临床或放射学反应没有统计学显着相关性。具有统计学上显着较高的药物水平。考虑到第 52 周的临床反应，第 2 周的 IFX 平均水平在无反应者中为 25.8μg/mL(SD 4.1)，在有反应者中为 30.9μg/mL(SD 14) (p=0.39)。第 w6 时，它们分别为 17.2μg/mL（SD 12.2）和 19.4μg/mL（SD 13.8）（p=0.7）。第 2 周时，无反应者的 ADA 平均水平为 13.3μg/mL（SD 7.7），有反应者的 ADA 平均水平为 14μg/mL（SD 6.3）（p=0.87）。第 w6 时，它们分别为 10.1 µg/mL（SD 3.3）和 12 µg/mL（SD 6.1）（p = 0.59）。对于第 52 周的放射学反应，第 2 周的 IFX 平均水平在无反应者中为 27μg/mL（SD 15.3），在有反应者中为 32.7μg/mL（SD 14.5）（p=0.45）。第 6 周时的平均水平分别为 15.9μg/mL（SD 6.7）和 23.7μg/mL（SD 14.8）（p=0.27）。在 ADA 组中，第 2 周有反应者的平均水平为 14.8 µg/mL（SD 7.6），只有一名患者没有反应。第 6 周时，无反应者的 ADA 平均水平为 12.3μg/mL（SD 5.9），有反应者的 ADA 平均水平为 12.7μg/mL（SD 6.2）（p=0.94）。第 24 周的早期反应与第 52 周的长期反应相关，第 52 周有反应的患者中有 89.9% 在第 24 周时已经有反应。结论 在我们的研究中，我们观察到几乎 90% 获得早期缓解的患者在第 52 周时也出现缓解，因此尝试实现早期缓解应该成为临床实践的目标。尽管患者数量有限，但我们的研究显示了较高的抗TNF水平与临床和放射学反应率之间的关系趋势