Leiden University Medical Center, Department of Orthopaedic Surgery, Albinusdreef 2, PO Box 9600, Postzone J-11-S, 2300 RC Leiden, the Netherlands.
Bone Joint Res. 2012 Oct 1;1(10):258-62. doi: 10.1302/2046-3758.110.2000104. Print 2012 Oct.
The Kaplan-Meier estimation is widely used in orthopedics to calculate the probability of revision surgery. Using data from a long-term follow-up study, we aimed to assess the amount of bias introduced by the Kaplan-Meier estimator in a competing risk setting.
We describe both the Kaplan-Meier estimator and the competing risk model, and explain why the competing risk model is a more appropriate approach to estimate the probability of revision surgery when patients die in a hip revision surgery cohort. In our study, a total of 62 acetabular revisions were performed. After a mean of 25 years, no patients were lost to follow-up, 13 patients had undergone revision surgery and 33 patients died of causes unrelated to their hip.
The Kaplan-Meier estimator overestimates the probability of revision surgery in our example by 3%, 11%, 28%, 32% and 60% at five, ten, 15, 20 and 25 years, respectively. As the cumulative incidence of the competing event increases over time, as does the amount of bias.
Ignoring competing risks leads to biased estimations of the probability of revision surgery. In order to guide choosing the appropriate statistical analysis in future clinical studies, we propose a flowchart.
Kaplan-Meier 估计在骨科中被广泛用于计算翻修手术的概率。我们使用长期随访研究的数据，旨在评估竞争风险环境下 Kaplan-Meier 估计器引入的偏差量。
我们描述了 Kaplan-Meier 估计器和竞争风险模型，并解释了为什么在髋关节翻修手术队列中患者死亡时，竞争风险模型是估计翻修手术概率的更合适方法。在我们的研究中，共进行了 62 例髋臼翻修术。平均随访 25 年后，无患者失访，13 例患者接受了翻修手术，33 例患者死于与髋关节无关的原因。
Kaplan-Meier 估计器在我们的示例中高估了翻修手术的概率，分别为 5 年、10 年、15 年、20 年和 25 年时的 3%、11%、28%、32%和 60%。随着竞争事件的累积发生率随时间的推移而增加，偏差量也随之增加。
忽略竞争风险会导致翻修手术概率的估计出现偏差。为了指导未来临床研究中选择适当的统计分析方法，我们提出了一个流程图。
