Wu YingXing, Takkenberg Johanna J M, Grunkemeier Gary L
Medical Data Research Center, Providence Health System, Portland, Oregon, USA.
Ann Thorac Surg. 2008 Apr;85(4):1155-7. doi: 10.1016/j.athoracsur.2007.12.012.
Completeness of follow-up is often used as a measure of the quality of follow-up, but the method used to compute it is often not declared. An ideal measure should be based on follow-up years instead of patients. Clark, Altman, and De Stavola proposed such a measure, called "C", which is the percentage of the maximum possible follow-up years, as of a given date, that has actually been accounted for or observed. However, such a measure will underestimate the true completeness, because the denominator (maximum possible follow-up years) does not account for unobserved patient deaths occurring before that date, and therefore, it is realistically unachievable. We propose a modification, C*, of Clark's C, which accounts for the effect of unobserved patient deaths in attenuating the maximum potential follow-up, and thus gives a higher percentage for achieved follow-up completeness. We validated this theoretical improvement by comparing the values of C and C* computed for our long-term coronary artery bypass graft patients to the true completeness, which was obtained by using the National Death Index to complete our missing follow-up data. Using Clark's C, the follow-up completeness was 80.4% and using our C* it is 84.5%, whereas the true follow-up completeness based on National Death Index information was 85.0%.
随访完整性常被用作衡量随访质量的指标，但计算该指标所采用的方法往往未被声明。理想的指标应基于随访年数而非患者数量。克拉克、阿尔特曼和德斯塔沃拉提出了这样一种指标，称为“C”，它是截至给定日期实际记录或观察到的最大可能随访年数的百分比。然而，这样的指标会低估真实的完整性，因为分母（最大可能随访年数）未考虑在该日期之前发生的未观察到的患者死亡情况，因此，实际上是无法达到的。我们提出了对克拉克的C指标的一种修正，即C*，它考虑了未观察到的患者死亡对最大潜在随访的削弱作用，从而为已实现的随访完整性给出更高的百分比。我们通过比较为我们的长期冠状动脉搭桥手术患者计算的C和C值与真实完整性进行了验证，真实完整性是通过使用国家死亡索引来补充我们缺失的随访数据而获得的。使用克拉克的C指标，随访完整性为80.4%，使用我们的C指标则为84.5%，而基于国家死亡索引信息的真实随访完整性为85.0%。
