Risk-Factor Clustering and Cardiovascular Disease Risk in Hypertensive Patients

Background Patients with hypertension often have other major risk factors for cardiovascular disease (CVD). Little is known, however, about the extent of risk-factor clustering in these patients and its importance in CVD risk and medical-care costs. Methods Study subjects were selected from the electronic medical records system of Kaiser Permanente Northwest, a large health maintenance organization, and included all patients aged ≥35 years with hypertension who were free of CVD in 1998. Subjects were stratified into eight risk-factor clusters based on whether or not they also had diabetes, hyperlipidemia, or a high body mass index (BMI). The risk of cardiovascular events was examined in each cluster over 6 years beginning January 1, 1999, using Kaplan-Meier methods and Cox proportional hazards models. Cumulative total medical-care costs (per patient) over 6 years also were examined. Results A total of 57,573 patients with hypertension who were free of CVD in 1998 were identified; 56% of subjects also had diabetes, hyperlipidemia, or high BMI. In analyses controlling for age, sex, and smoking status, the relative risk of cardiovascular events over 6 years was highest for patients with comorbid diabetes, ranging from 2.07 (95% confidence interval, 1.86–2.30) for those with diabetes only to 2.80 (95% confidence interval, 2.48–3.17) for those with diabetes, hyperlipidemia, and high BMI. Cumulative medical-care costs generally increased with additional risk factors. Comorbid diabetes had the greatest impact on costs over 6 years. Conclusions More than 50% of patients with hypertension also had diabetes, hyperlipidemia, or high BMI. Patients with these additional risk factors (especially diabetes) had a substantially higher CVD risk and medical-care costs.