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

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Abstract

Background

The Hypertension Optimal Treatment (HOT) Study has provided information about cardiovascular events in 18 790 hypertensives, subjected to pronounced blood pressure (BP) lowering for a mean of 3.8 years. The HOT study data have subsequently been analysed after stratification of the patients according to global cardiovascular risk, and it has been found that, despite intensive blood pressure lowering in all risk strata, morbid event rates increased with increasing risk stratum.

Objectives

Previously analysed global risk strata were based on combinations of risk factors. The analyses presented here were intended to provide information on the relative role that the presence of each individual factor may 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 examination.

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 statistically significant risk for cardiovascular (CV) events, CV and total mortality and particularly for myocardial infarction (MI); age ≥ 65 years for CV events, stroke, CV and particularly total mortality; smoking for all events analysed, but particularly for total mortality (twice higher in smokers than in non-smokers); high serum cholesterol (> 6.8 mmol/l) for CV events, MI and CV mortality; high serum creatinine (> 155 μmol/l) for CV events, stroke, CV and total mortality; diabetes for CV events, stroke, total mortality and particularly CV mortality; and ischaemic heart disease for all events analysed. Adjusted RR were often close to or greater than 2.

Conclusions

Each of the risk factors considered was found to be an important 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 pressure, and of initiating antihypertensive therapy before cardiovascular and renal damage becomes manifest.

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