A score for the prediction of cardiovascular events in the hypertensive aged
Nelson, MR and Ryan, P and Tonkin, AM and Ramsay, E and Willson, K and Simons, L and Reid, CM and Wing, LMH, A score for the prediction of cardiovascular events in the hypertensive aged, Heart Foundation Conference, March, Melbourne, Australia (2011) [Conference Extract]
Objective: With the exception of SCORE ELD and the Dubbo risk equations, tools used to estimate risk in those without prior cardiovascular disease (CVD) events are based particularly on data from middle-aged subjects. Most persons aged 65 years and above have hypertension. A global risk score is needed for them. Our aim was to develop an equation, based on cardiovascular endpoints from 4.1 years median follow up in the Second Australian National Blood Pressure Study (ANBP2), suitable for risk prediction in the elderly, hypertensive Australian population.
Methods: ANBP2 was an RCT in 6083 patients with mild-moderate hypertension. Our risk model, based on Cox regression, was developed using ¾ of subjects (n=4565), randomly selected and stratified by age and gender, and validated using the remaining ¼. It was externally validated against the Dubbo study.
Results: The final model included sex, family history, anti-coagulation use, centrally acting antihypertensive agent use, diabetes medication use. Age and gender were the best predictors of CVD events and all other potential predictors (both demographic and clinical), quadratic terms and interactions added little to the model. Dubbo Data C-statistic for CVD was 0.69 (95% CI 0.66 - 0.72). C-statistic was 0.65 (0.62 - 0.67) for our predictive model.
Conclusions: Our final model was not superior to existing CVD risk algorithms. The C-statistic for our data was similar to those observed when existing algorithms such as Framingham were applied to the ANBP2 cohort, indicating that their utility can be extended into older age groups.