Cluster analysis identifies three urodynamic patterns in patients with orthotopic neobladder reconstruction

Purpose
To classify patients with orthotopic neobladder based on urodynamic parameters using cluster analysis and to characterize the voiding function of each group.
Materials and methods
From January 2012 to November 2015, 142 patients with bladder cancer underwent radical cystectomy and Studer neobladder reconstruction at our institute. Of the 142 patients, 103 with complete urodynamic data and information on urinary functional outcomes were included in this study. K-means clustering was performed with urodynamic parameters which included maximal cystometric capacity, residual volume, maximal flow rate, compliance, and detrusor pressure at maximum flow rate. Three groups emerged by cluster analysis. Urodynamic parameters and urinary function outcomes were compared between three groups.
Results
Group 1 (n = 44) had ideal urodynamic parameters with a mean maximal bladder capacity of 513.3 ml and mean residual urine volume of 33.1 ml. Group 2 (n = 42) was characterized by small bladder capacity with low compliance. Patients in group 2 had higher rates of daytime incontinence and nighttime incontinence than patients in group 1. Group 3 (n = 17) was characterized by large residual urine volume with high compliance. When we examined gender differences in urodynamics and functional outcomes, residual urine volume and the rate of daytime incontinence were only marginally significant. However, females were significantly more likely to belong to group 2 or 3 (P = 0.003). In multivariate analysis to identify factors associated with group 1 which has the most ideal urodynamic pattern, age (OR 0.95, P = 0.017) and male gender (OR 7.57, P = 0.003) were identified as significant factors.
Conclusions
While patients with ileal neobladder present with various voiding symptoms, three urodynamic patterns were identified by cluster analysis. Approximately half of patients had ideal urodynamic parameters. The other two groups were characterized by large residual urine and small capacity bladder with low compliance. Young age and male gender appear to have a favorable impact on urodynamic and voiding outcomes in patients undergoing orthotopic neobladder reconstruction.

研究目的
本研究旨在通过聚类分析（cluster analysis），基于尿流动力学参数对原位新膀胱（orthotopic neobladder）患者进行分类，并阐明各组的排尿功能特征。

材料与方法
本中心于2012年1月至2015年11月期间，共收治142例膀胱癌患者，均接受根治性膀胱切除术联合斯图德新膀胱（Studer neobladder）重建术。最终纳入本研究的103例患者均具备完整的尿流动力学参数与排尿功能结局相关资料。本研究采用K均值聚类（K-means clustering）分析，纳入的尿流动力学参数包括最大膀胱测压容积、残余尿量、最大尿流率、膀胱顺应性及最大尿流率时逼尿肌压力。经聚类分析后，所有患者被划分为3个组别，随后对3组间的尿流动力学参数与排尿功能结局进行比较。

研究结果
第1组（n=44）的尿流动力学参数处于理想状态，其平均最大膀胱容量为513.3ml，平均残余尿量为33.1ml。第2组（n=42）以膀胱容量偏小且顺应性低下为主要特征，该组患者日间尿失禁与夜间尿失禁的发生率均显著高于第1组。第3组（n=17）则以残余尿量偏大且顺应性偏高为特征。在分析尿流动力学与功能结局的性别差异时，仅残余尿量与日间尿失禁发生率呈现边缘显著性差异；而女性患者归属第2组或第3组的概率显著更高（P=0.003）。针对与最理想尿流动力学表型的第1组相关的影响因素开展多因素分析（multivariate analysis）后，确定年龄（比值比（odds ratio, OR）=0.95，P=0.017）与男性性别（OR=7.57，P=0.003）为显著影响因素。

研究结论
尽管回肠原位新膀胱（ileal neobladder）患者可出现多种排尿症状，但通过聚类分析可将其划分为3种尿流动力学表型。约半数患者的尿流动力学参数处于理想状态，其余两组分别以残余尿量偏大与膀胱容量偏小、顺应性低下为主要特征。年轻与男性性别似乎对接受原位新膀胱重建术患者的尿流动力学及排尿功能结局具有积极影响。