[Influence of some parameters on the blood pressure reduction under treatment: experience from the Hypertension Optimal Treatment Study].

The HOT study is the largest controlled therapeutic trial conducted to date in hypertension. This international, prospective, randomised trial is designed to determine the optimal blood pressure to be obtained during treatment, in order to achieve optimal reduction of complications and cardiovascular mortality. The HOT study is conducted according to the PROBE methodology (Prospective Randomised Open Blinded Endpoints. It has three objectives: 1) to evaluate the relationship between the development of major cardiovascular events and the DBP target level (DBP < or = 90, DBP < or = 85 or DBP < or = 80 mmHg. 2) to evaluate the relationship between the development of major cardiovascular events and real DBP observed, 3) to determine whether low-dose acetylsalicylic acid (75 mg/day) provides an additional benefit in terms of cardiovascular morbidity and mortality in treated hypertensive subjects. Between April 1992 and October 1994, 18,790 patients, between the ages of 50 and 80 years (26 countries), were randomised to these 3 target DBP groups and several parameters likely to influence the blood pressure fall were identified. The reduction of DBP was all the more pronounced the higher the baseline DBP. For a baseline DBP equal to 100 mmHg, the mean fall was 18 mmHg and for a baseline DBP equal to 110 mmHg, the mean fall was 27 mmHg. Advanced age was also found to be a factor promoting reduction of DBP, which increased after the age of 65 years. Analysed in relation to the type of treatment, this more marked reduction in the elderly showed that monotherapy with a calcium channel blocker was very effective on DBP and especially after the age of 75 years. The data of the study also showed that SBP decreased in parallel to DBP, but to an even greater extent. Thus, a 10 mmHg reduction of DBP induces a reduction of SBP by approximately 20 mmHg. This reduction of SBP related to the level of DBP was even more marked the higher the baseline SBP and the higher the target DBP objective. Thus 80% of patients in the DBP < or = 80 mmHg group had an SBP < or = 150 mmHg during treatment. Among the other factors, weight appeared to clearly influence reduction of DBP, as the reduction of DBP was more marked the lower the patient's weight. In contrast, the body mass index was poorly correlated with the reduction in blood pressure. The blood pressure reduction, regardless of weight, was more marked when a stricter blood pressure objective was adopted (DBP < or = 80 mmHg). Finally, in the particular case of elderly subjects, treatment with a calcium channel blocker appeared to be very effective in reducing the blood pressure.