INFLUENCE OF SOME PARAMETERS ON THE BLOOD-PRESSURE REDUCTION UNDER TREATMENT - EXPERIENCE FROM THE HOT STUDY

The HOT study is the largest controlled therapeutic trial conducted to date in hypertension. This international, prospective, randomised tri al is designed to determine the optimal blood pressure to be obtained during treatment, in order to achieve optimal reduction of complicatio ns and cardiovascular mortality.The HOT study is conducted according t o the PROBE methodology (Prospective Randomised Open Blinded-Endpoints . It has three objectives : 1) to evaluate the relationship between th e development of major cardiovascular events and the DBP target level (DBP less than or equal to 90, DBP less than or equal to 85 or DBP les s than or equal to 80 mmHg, 2) to evaluate the relationship between th e development of major cardiovascular events and real DBP observed, 3) to determine whether low-dose acetylsalicylic acid (75 mg/day) provid es an additional benefit in terms of cardiovascular morbidity and mort ality in treated hypertensive subjects. Between April 1992 and October 1994, 18 790 patients, between the ages of SO and 80 years (26 countr ies), were randomised to these 3 target DBP groups and several paramet ers likely to influence the blood pressure fall were identified.The re duction 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. Advan ced age was also found to be a factor promoting reduction of DBP, whic h increased after the age of 65 years. Analysed in relation to the typ e of treatment, this more marked reduction in the elderly showed that monotherapy with a calcium channel blocker was very effective on DBP a nd especially after the age of 75 years. The data of the study also sh owed that SEP decreased in parallel to DBP, but to an even greater ext ent. Thus, a 10 mmHg reduction of DBP induces a reduction of SEP by ap proximately 20 mmHg. This reduction of SEP related to the level of DBP was even more marked the higher the baseline SEP and the higher the t arget DBP objective. Thus 80% of patients in the DBP less than or equa l to 80 mmHg group had an SEP less than or equal to 150 mmHg during tr eatment. Among the other factors, weight appeared to clearly influence reduction of DBP, as the reduction of DBP was more marked the lower t he patient's weight. In contrast, the body mass index was poorly corre lated with the reduction in blood pressure. The blood pressure reducti on, regardless of weight, was more marked when a stricter blood pressu re objective was adopted (DBP less than or equal to 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 pr essure.