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决策树在传染病现场调查中的应用
传染病现场调查是一项专业性和社会实践性很强的工作,具有很重要的现实意义.通过现场调查,可以掌握传染病疫情的第一手资料,尽早发现可疑的流行因素并及时控制疫情.
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Objective:We investigated the prognostic value of the lymph node ratio (LNR), determined different cut-points in cohorts with examined lymph nodes (eLNs)≤15 or eLNs >15, and compared hypothetical pNr with 7th edition UICC pN stage.Methods:A total of 1,772 gastric cancer patients undergoing D2 resection were enrolled. All patients were divided into two sub-cohorts according to eLNs≤15 or eLNs >15. The optimal LNR cut-point was calculated using decision tree method. Homogeneity, discriminatory ability, and monotonicity of gradients of the pNr and UICC pNstages were compared using linear trendχ2, likelihood ratioχ2 statistics, and Akaike information criterion (AIC) calculations.Results:hTe optimal cut-points were 0, 20, 35, 65 in eLNs >15 cohort and 0, 35, 70 in eLNs≤15 cohort. pNr stage was an independent factor for gastric cancer prognosis. hTe pNr stage had higher linear trend and likelihood ratioχ2 scores and lower AIC values compared with those for UICC pN stage.Conclusion:The LNR cut-point should be different according to the numbers of eLNs. pNr can predict survival more accurately than UICC pN stage in both the≤15 and the >15 eLNs cohorts.
