Department of Health, Long-term Care and Pensions, SOCIUM Research Center on Inequality and Social Policy, University of Bremen, P.O. Box 33 04 40, 28334, Bremen, Germany.
High-Profile Area Health Sciences, University of Bremen, P.O. Box 33 04 40, 28334, Bremen, Germany.
BMC Med Res Methodol. 2017 Aug 14;17(1):122. doi: 10.1186/s12874-017-0407-4.
This cohort study examined the impact of the lengths of lookback and confirmation periods as well as the definition of confirmatory events on the number of incident cancer cases identified and age-standardized cumulative incidences (ACI) estimated in administrative data using German cancer registry data as a benchmark.
ACI per 100,000 insured persons for breast, prostate and colorectal cancer were estimated using BARMER Statutory Health Insurance claims data. Incident cancer cases were defined as having an in- or outpatient diagnosis in 2013, no diagnosis in a lookback period of 1 year and a second diagnosis (or death) in a confirmation period of 1 quarter. We varied lookback periods from 1 to 7 years, confirmation periods from 1 to 4 quarters as well as the definition of confirmatory events and compared ACI estimates to cancer registry data.
ACI were higher for breast (138.7) and prostate (103.6) but lower for colorectal cancer (42.1) when compared to cancer registries (119.3, 98.0 and 45.5, respectively). Extending the lookback period to 7 years reduced ACI to 129.0, 95.1 and 38.3. An extended confirmation period of 4 quarters increased ACI to 151.3, 114.9 and 46.8. Including breast and colorectal surgeries as a confirmatory event reduced ACI to 114.9 and 37.1, respectively.
The choice of lookback and confirmation periods and the definition of confirmatory events have considerable impact on the number of incident cancer cases identified and ACI estimated. Researchers need to be aware of potential misclassification when identifying incident cancer cases in administrative data. Further validation studies as well as studies using administrative data to estimate cancer incidences should consider several choices of the lookback and confirmation periods and the definition of confirmatory events to show how these parameters impact the validity and robustness of their results.
本队列研究考察了回溯期和确认期的长度以及确认事件的定义对使用德国癌症登记数据作为基准的行政数据中确定的新发癌症病例数量和年龄标准化累积发病率（ACI）估计值的影响。
使用 BARMER 法定健康保险索赔数据估计每 10 万名参保人患乳腺癌、前列腺癌和结直肠癌的 ACI。新发癌症病例定义为 2013 年有门诊或住院诊断，在 1 年回溯期内无诊断，在 1 个季度确认期内有第二次诊断（或死亡）。我们改变了回溯期从 1 年到 7 年，确认期从 1 个季度到 4 个季度，以及确认事件的定义，并将 ACI 估计值与癌症登记数据进行比较。
与癌症登记数据相比，乳腺癌（138.7）和前列腺癌（103.6）的 ACI 较高（分别为 119.3、98.0 和 45.5），而结直肠癌（42.1）的 ACI 较低。将回溯期延长至 7 年，将 ACI 降低至 129.0、95.1 和 38.3。将确认期延长至 4 个季度，将 ACI 增加至 151.3、114.9 和 46.8。将乳房和结直肠手术作为确认事件，将 ACI 分别降低至 114.9 和 37.1。
回溯期和确认期的选择以及确认事件的定义对确定的新发癌症病例数量和估计的 ACI 有很大影响。在行政数据中确定新发癌症病例时，研究人员需要意识到潜在的错误分类。进一步的验证研究以及使用行政数据估计癌症发病率的研究应考虑回溯期和确认期的几个选择以及确认事件的定义，以展示这些参数如何影响其结果的有效性和稳健性。
