Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
Department of Health and Caring Sciences, Western Norway University of Applied Sciences, Bergen, Hordaland, Norway.
BMJ Open. 2024 Mar 28;14(3):e077027. doi: 10.1136/bmjopen-2023-077027.
The prescription-based Rx-risk index has previously been developed to measure multimorbidity. We aimed to adapt and evaluate the validity of the Rx-risk index in prediction of mortality among persons with type 2 diabetes.
Registry-based study.
Adults with type 2 diabetes in Norway identified within the 'Outcomes and Multimorbidity In Type 2 diabetes' cohort, with linkage to prescriptions from the Norwegian Prescription Database and mortality from the Population Registry.
We defined a calibration sample of 42 290 adults diagnosed with type 2 diabetes 1950-2013, and a temporal validation sample of 7085 adults diagnosed 2014-2016 to evaluate the index validity over time PRIMARY OUTCOME MEASURE: All-cause mortality METHODS: For the calibration sample, dispensed drug prescriptions in 2013 were used to define 44 morbidity categories. Weights were estimated using regression coefficients from a Cox regression model with 5 year mortality as the outcome and all morbidity categories, age and sex included as covariates. The Rx-risk index was computed as a weighted sum of morbidities. The validity of the index was evaluated using C-statistic and calibration plots.
In the calibration sample, mean (SD) age at start of follow-up and duration of diabetes was 63.8 (12.4) and 10.1 (7.0) years, respectively. The overall C-statistic was 0.82 and varied from 0.74 to 0.85 when stratifying on age groups, sex, level of education and country of origin. In the validation sample, mean (SD) age and duration of diabetes was 59.7 (13.0) and 2.0 (0.8) years, respectively. Despite younger age, shorter duration of diabetes and later time period, the C-index was high both in the total sample (0.84) and separately for men (0.83) and women (0.84).
The Rx-risk index showed good discrimination and calibration in predicting mortality and thus presents a valid tool to assess multimorbidity among persons with type 2 diabetes.
基于处方的 Rx 风险指数先前已被开发用于衡量多种疾病。我们旨在调整并评估 Rx 风险指数在预测 2 型糖尿病患者死亡率方面的有效性。
基于注册的研究。
在“2 型糖尿病结局和多种疾病”队列中识别出的挪威 2 型糖尿病成年人，与挪威处方数据库中的处方和人口登记处的死亡率相关联。
我们定义了一个校准样本，包括 42290 名 1950 年至 2013 年确诊的 2 型糖尿病患者，以及一个 2014 年至 2016 年确诊的 7085 名患者的时间验证样本，以评估该指数的有效性随时间的变化。
全因死亡率
对于校准样本，使用 2013 年配药的药物处方来定义 44 种疾病类别。使用 Cox 回归模型的回归系数估计权重，该模型的结局为 5 年死亡率，所有疾病类别、年龄和性别均作为协变量。Rx 风险指数是通过对疾病进行加权求和计算得出的。使用 C 统计量和校准图评估该指数的有效性。
在校准样本中，随访开始时的平均（SD）年龄和糖尿病病程分别为 63.8（12.4）岁和 10.1（7.0）年。整体 C 统计量为 0.82，当按年龄组、性别、教育水平和原籍国进行分层时，范围为 0.74 至 0.85。在验证样本中，平均（SD）年龄和糖尿病病程分别为 59.7（13.0）岁和 2.0（0.8）年。尽管年龄较小、糖尿病病程较短、时间较晚，但在总样本（0.84）以及男性（0.83）和女性（0.84）中，C 指数均较高。
Rx 风险指数在预测死亡率方面表现出良好的区分度和校准度，因此是评估 2 型糖尿病患者多种疾病的有效工具。
