Effects of individual risk factors on the incidence of cardiovascular events in the treated hypertensive patients of the Hypertension Optimal Treatment Study

Background The Hypertension Optimal Treatment (HOT) Study has provided info rmation about cardiovascular events in 18 790 hypertensives, subjected to p ronounced blood pressure (BP) lowering for a mean of 3.8 years. The HOT stu dy data have subsequently been analysed after stratification of the patient s according to global cardiovascular risk, and it has been found that, desp ite intensive blood pressure lowering in all risk strata, morbid event rate s increased with increasing risk stratum. Objectives Previously analysed global risk strata were based on combination s of risk factors. The analyses presented here were intended to provide inf ormation on the relative role that the presence of each individual factor m ay have in increasing cardiovascular risk, despite good BP control. Methods Risk ratios (RR) for patients with and those without a risk factor were calculated with 95% confidence intervals (CI) using a Cox proportional hazard model, and adjusted for all variables except the one under examinat ion. Results For all risk factors considered and for all types of event, RR were always greater than 1, indicating a greater risk in the presence, compared with that in the absence of each factor. The male gender was a statistical ly significant risk for cardiovascular (CV) events, CV and total mortality and particularly for myocardial infarction (MI); age greater than or equal to 65 years for CV events, stroke, CV and particularly total mortality; smo king for all events analysed, but particularly for total mortality (twice h igher in smokers than in non-smokers); high serum cholesterol (> 6.8 mmol/l ) for CV events, MI and CV mortality; high serum creatinine (> 155 mu mol/l ) for CV events, stroke, CV and total mortality; diabetes for CV events, st roke, total mortality and particularly CV mortality; and ischaemic heart di sease for all events analysed. Adjusted RR were often close to or greater t han 2. Conclusions Each of the risk factors considered was found to be an importan t cause of residual risk, despite good BP control. These findings emphasize the importance of addressing other correctable risk factors, e.g. smoking, hypercholesterolaemia and diabetes, as well as rigorous control of blood p ressure, and of initiating antihypertensive therapy before cardiovascular a nd renal damage becomes manifest. (C) 2001 Lippincott Williams & Wilkins.