Teixeira Laetitia, Rodrigues Anabela, Carvalho Maria J, Cabrita António, Mendonça Denisa
BMC Nephrol. 2013 May 24;14:110. doi: 10.1186/1471-2369-14-110.
Modelling competing risks is an essential issue in Nephrology Research. In peritoneal dialysis studies, sometimes inappropriate methods (i.e. Kaplan-Meier method) have been used to estimate probabilities for an event of interest in the presence of competing risks. In this situation a competing risk analysis should be preferable. The objectives of this study are to describe the bias resulting from the application of standard survival analysis to estimate peritonitis-free patient survival and to provide alternative statistical approaches taking competing risks into account.
The sample comprises patients included in a university hospital peritoneal dialysis program between October 1985 and June 2011 (n = 449). Cumulative incidence function and competing risk regression models based on cause-specific and subdistribution hazards were discussed.
The probability of occurrence of the first peritonitis is wrongly overestimated using Kaplan-Meier method. The cause-specific hazard model showed that factors associated with shorter time to first peritonitis were age (≥55 years) and previous treatment (haemodialysis). Taking competing risks into account in the subdistribution hazard model, age remained significant while gender (female) but not previous treatment was identified as a factor associated with a higher probability of first peritonitis event.
In the presence of competing risks outcomes, Kaplan-Meier estimates are biased as they overestimated the probability of the occurrence of an event of interest. Methods which take competing risks into account provide unbiased estimates of cumulative incidence for each specific outcome experienced by patients. Multivariable regression models such as those based on cause-specific hazard and on subdistribution hazard should be used in this competing risk setting.
对竞争风险进行建模是肾脏病学研究中的一个重要问题。在腹膜透析研究中，有时会使用不恰当的方法（如Kaplan-Meier法）来估计在存在竞争风险的情况下感兴趣事件的概率。在这种情况下，进行竞争风险分析可能更可取。本研究的目的是描述应用标准生存分析来估计无腹膜炎患者生存率所导致的偏差，并提供考虑竞争风险的替代统计方法。
样本包括1985年10月至2011年6月期间纳入某大学医院腹膜透析项目的患者（n = 449）。讨论了基于特定病因和亚分布风险的累积发病率函数和竞争风险回归模型。
使用Kaplan-Meier法会错误地高估首次发生腹膜炎的概率。特定病因风险模型显示，与首次发生腹膜炎时间较短相关的因素是年龄（≥55岁）和既往治疗（血液透析）。在亚分布风险模型中考虑竞争风险后，年龄仍然具有显著性，而性别（女性）而非既往治疗被确定为与首次发生腹膜炎事件概率较高相关的因素。
在存在竞争风险结局的情况下，Kaplan-Meier估计存在偏差，因为它们高估了感兴趣事件发生的概率。考虑竞争风险的方法可为患者经历的每个特定结局提供无偏的累积发病率估计。在这种竞争风险情况下，应使用多变量回归模型，如基于特定病因风险和亚分布风险的模型。
