(A) study on combinations with repetition via occupapancy problems

학위논문 (석사)-- 서울대학교 대학원 : 수학교육과, 2011.8. 김서령.Maste

The effect of therapeutic leukapheresis on early complications and outcomes in patients with acute leukemia and hyperleukocytosis: a propensity score-matched study

BACKGROUND: Hyperleukocytosis in acute leukemia is associated with higher early mortality due to the major complications of leukostasis, tumor lysis syndrome (TLS), and disseminated intravascular coagulopathy (DIC). Leukapheresis remains an important modality for the management of patients with acute leukemia and hyperleukocytosis. However, the role of leukapheresis in early mortality is controversial. This study sought to evaluate the prognostic impact of leukapheresis and its beneficial effects on TLS and DIC. STUDY DESIGN AND METHODS: We conducted a propensity score-matched study of 166 patients with acute leukemia and hyperleukocytosis admitted between 2006 and 2016. The incidence of TLS and DIC was determined using well-defined Cairo-Bishop criteria for TLS and International Society of Thrombosis and Haemostasis criteria for DIC. RESULTS: Before matching, 27 of 91 patients (30%) with acute myeloid leukemia (AML) and 32 of 75 patients (43%) with acute lymphoblastic leukemia (ALL) underwent leukapheresis. Propensity score matching was performed to adjust for clinical disparities between the leukapheresis and without-leukapheresis groups and resulted in 22 matched pairs of patients with AML and 16 matched pairs of patients with ALL. After matching, we observed no significant difference in early mortality rates or in the incidence of TLS or DIC between the two groups of patients with AML and ALL. CONCLUSION: Although leukapheresis may rapidly reduce white blood cell counts and leukemic blasts, any positive influence of leukapheresis could not be demonstrated by an effect on survival outcome and the incidence of early complications, such as TLS and DIC. These results suggest that a routinely performed, prophylactic leukapheresis cannot be recommended.restrictio

Prediction model for bleeding after endoscopic submucosal dissection of gastric neoplasms from a high-volume center

Background and aim: Bleeding after endoscopic submucosal dissection (ESD) is a main adverse event. To date, although there have been several studies about risk factors for post-ESD bleeding, there has been few predictive model for post-ESD bleeding with large volume cases. We aimed to design a prediction model for post-ESD bleeding using a classification tree model. Methods: We analyzed a prospectively established cohort of patients with gastric neoplasms treated with ESD from 2007 to 2016. Baseline characteristics were collected for a total of 5080 patients, and the bleeding risk was estimated using variable statistical methods such as logistic regression, AdaBoost, and random forest. To investigate how bleeding was affected by independent predictors, the classification and regression tree (CART) method was used. The prediction tree developed for the cohort was internally validated. Results: Post-ESD bleeding occurred in 262 of 5080 patients (5.1%). In multivariate logistic regression, ongoing antithrombotic use during the procedure, cancer pathology, and piecemeal resection were significant risk factors for post-ESD bleeding. In the CART model, the decisive variables were ongoing antithrombotic agent use, resected specimen size ≥49 mm, and patient age <62 years. The CART model accuracy was 94.9%, and the cross-validation accuracy was 94.8%. Conclusions: We developed a simple and easy-to-apply predictive tree model based on three risk factors that could help endoscopists identify patients at a high risk of bleeding. This model will enable clinicians to establish precise management strategies for patients at a high risk of bleeding and to prevent post-ESD bleeding.restrictio