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Cardiovascular risk and diabetes. Are the methods of risk prediction satisfactory?
Jeffrey W Stephens1, Gareth Ambler, Patrick Vallance
1Department of Diabetes & Endocrinology, UCL Hospitals, Mortimer Street, London, UK. rmhajst@ucl.ac.uk
Insights
Cardiovascular disease (CVD) and coronary heart disease (CHD) risk prediction tools generally underestimate future events in diabetic patients. The CardioRisk Manager (CRM) calculator demonstrated the strongest correlation between observed and predicted risk, suggesting it is the most accurate method.
Area of Science:
- Cardiology
- Diabetology
- Public Health
Background:
- Existing cardiovascular disease (CVD) and coronary heart disease (CHD) risk prediction methods include the Joint British Societies Risk Chart (JBSRC), CardioRisk Manager (CRM), PROCAM, and UKPDS risk engine.
- Efficacy of these tools in predicting risk within a diabetic patient population requires examination.
Purpose of the Study:
- To evaluate the accuracy of established CVD and CHD risk prediction tools in a clinic-based diabetic population.
- To compare the performance of JBSRC, CRM, PROCAM, and UKPDS risk engine in predicting 10-year risk.
Main Methods:
- A cohort of 798 diabetic patients was identified from baseline (1990-1991) and follow-up (2000-2001) data.
- Ten-year CVD and CHD risk was calculated using JBSRC, CRM, PROCAM, and UKPDS.
- Risk prediction accuracy was assessed using the Hosmer-Lemeshow test (calibration), C-index (discrimination), and Spearman correlation.
Main Results:
- All tested risk prediction methods, except PROCAM, showed acceptable discrimination for CHD/CVD.
- All methods tended to underestimate the risk of future cardiovascular events.
- The CardioRisk Manager (CRM) exhibited the highest C-index for CVD (0.76) and a strong correlation (r=0.97) between observed and predicted risk.
Conclusions:
- While all risk scores offer reasonable discrimination, they underestimate future cardiovascular events in diabetic patients.
- The CRM calculator, particularly when adjusted for calibration, provides the most accurate risk prediction among the evaluated tools.
- The CRM's superior performance is indicated by its strong correlation between observed and predicted risk and minimal scatter.
Background:
Methods available to predict cardiovascular disease (CVD) and coronary heart disease (CHD) risk include the Joint British Societies Risk Chart (JBSRC), the CardioRisk Manager (CRM) calculator, the PROCAM calculation and specific to diabetes, the UKPDS risk engine. Our aim was to examine their efficacy in a clinic-based population of diabetic patients.
Design:
Patients were identified who attended clinic at baseline (1990-1991) and categorised by the presence/absence of CHD/CVD at follow-up (2000-2001). Ten-year risk was calculated using JBSRC, CRM, PROCAM and the UKPDS risk engine.
Methods:
A total of 798 patients were identified under follow-up (2000-2001), with sufficient data for risk prediction. Risk prediction methods were assessed by: (1) the Hosmer-Lemeshow test (calibration test); (2) the C-index, derived from the ROC curve [a discriminatory measure ranging from 0.5 (no discrimination) to 1.0 (perfect discrimination)]; and (3) Spearman correlation of the observed and predicted risk.
Results:
All tests (except PROCAM) demonstrated acceptable discrimination with respect to CHD/CVD, however, all underestimated the risk of future events. With respect to CVD, the JBSRC had a C-index of 0.80, CRM: 0.76, UKPDS: 0.74 and PROCAM: 0.67. With respect to CHD the C-indexes were 0.77, 0.73, 0.65 and 0.76 respectively. Risk prediction by CRM had a stronger relationship with observed events than UKPDS and PROCAM (r=0.97, 0.86, 0.81 respectively).
Conclusions:
All scores have reasonable discrimination, but underestimate future events. The CRM showed the strongest correlation between observed and predicted risk with the least amount of scatter from the line of best fit. The CRM, when adjusted by the calibration factor, provides the most accurate method of risk prediction.
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