Mühlenbruch Kristin, Paprott Rebecca, Joost Hans-Georg, Boeing Heiner, Heidemann Christin, Schulze Matthias B
Department of Molecular Epidemiology, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany.
German Center for Diabetes Research (DZD), München-Neuherberg, Germany.
BMJ Open Diabetes Res Care. 2018 Jul 6;6(1):e000524. doi: 10.1136/bmjdrc-2018-000524. eCollection 2018.
The German Diabetes Risk Score (GDRS) is a diabetes prediction model which only includes non-invasively measured risk factors. The aim of this study was to extend the original GDRS by hemoglobin A1c (HbA1c) and validate this clinical GDRS in the nationwide German National Health Interview and Examination Survey 1998 (GNHIES98) cohort.
Extension of the GDRS was based on the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study with baseline assessment conducted between 1994 and 1998 (N=27 548, main age range 35-65 years). Cox regression was applied with the original GDRS and HbA1c as independent variables. The extended model was evaluated by discrimination (-index (95% CI)), calibration (calibration plots and expected to observed (E:O) ratios (95% CI)), and reclassification (net reclassification improvement, NRI (95% CI)). For validation, data from the GNHIES98 cohort with baseline assessment conducted between 1997 and 1999 were used (N=3717, age range 18-79 years). Missing data were handled with multiple imputation.
After 5 years of follow-up 593 incident cases of type 2 diabetes occurred in EPIC-Potsdam and 86 in the GNHIES98 cohort. In EPIC-Potsdam, the -index for the clinical GDRS was 0.87 (0.81 to 0.92) and the overall NRI was 0.26 (0.21 to 0.30), with a stronger improvement among cases compared with non-cases (NRI: 0.24 (0.19 to 0.28); NRI: 0.02 (0.01 to 0.02)). Almost perfect calibration was observed with a slight tendency toward overestimation, which was also reflected by an E:O ratio of 1.07 (0.99 to 1.16). In the GNHIES98 cohort, discrimination was excellent with a -index of 0.91 (0.88 to 0.94). After recalibration, the calibration plot showed underestimation of diabetes risk in the highest risk group, while the E:O ratio indicated overall perfect calibration (1.02 (0.83 to 1.26)).
The clinical GDRS provides the opportunity to apply the original GDRS as a first step in risk assessment, which can then be extended in clinical practice with HbA1c whenever it was measured.
德国糖尿病风险评分（GDRS）是一种仅包含非侵入性测量风险因素的糖尿病预测模型。本研究的目的是将糖化血红蛋白（HbA1c）纳入原始GDRS并在1998年德国全国健康访谈与检查调查（GNHIES98）队列中验证这一临床GDRS。
GDRS的扩展基于欧洲癌症与营养前瞻性调查（EPIC）-波茨坦研究，该研究在1994年至1998年进行了基线评估（N = 27548，主要年龄范围为35 - 65岁）。以原始GDRS和HbA1c作为自变量应用Cox回归。通过区分度（-指数（95%置信区间））、校准（校准图和预期与观察（E:O）比率（95%置信区间））和重新分类（净重新分类改善，NRI（95%置信区间））对扩展模型进行评估。为进行验证，使用了1997年至1999年进行基线评估的GNHIES98队列的数据（N = 3717，年龄范围为18 - 79岁）。缺失数据采用多重填补法处理。
在EPIC - 波茨坦队列中，经过5年随访，发生了593例2型糖尿病新发病例，在GNHIES98队列中为86例。在EPIC - 波茨坦队列中，临床GDRS的-指数为0.87（0.81至0.92），总体NRI为0.26（0.21至0.30），病例组的改善比非病例组更强（NRI：0.24（0.仃至0.28）；NRI：0.02（0.01至0.02））。观察到几乎完美的校准，有轻微的高估倾向，这也反映在E:O比率为1.07（0.99至1.16）上。在GNHIES98队列中，区分度极佳，-指数为0.91（0.88至0.94）。重新校准后，校准图显示在最高风险组中低估了糖尿病风险，而E:O比率表明总体校准完美（1.02（0.83至1.26））。
临床GDRS提供了将原始GDRS作为风险评估第一步应用的机会，然后在临床实践中只要测量了HbA1c就可以对其进行扩展。
