Obesity as a determinant for response to antihypertensive treatment.

OBJECTIVE

To test the hypothesis that beta blockers lower blood pressure more effectively than calcium entry blockers in obese hypertensive patients and that calcium entry blockers are more effective in lean patients.

DESIGN

Double blind, randomised controlled trial of treatment over six weeks.

SETTING

Tertiary referral centre.

SUBJECTS

42 white men with uncomplicated mild to moderate essential hypertension (World Health Organisation stage I or II); 36 completed the study.

INTERVENTION

Patients were randomised to metoprolol 50-100 mg twice daily or isradipine 2.5-5.0 mg twice daily for six weeks after a two week run in phase.

MAIN OUTCOME MEASURE

Blood pressure after six weeks of treatment.

RESULTS

When stratified according to treatment and presence of obesity (body mass index < or = 27 kg/m2), the mean (SD) fall in blood pressure in the beta blocker group was 24 (13)/18 (10) mm Hg in obese patients and 18 (19)/12 (13) mm Hg in lean patients. In the calcium entry blocker group, the fall in blood pressure was 21 (15)/17 (6) mm Hg in lean patients and 18 (11)/8 (10) mm Hg in obese patients. After taking age and blood pressure before treatment into account there was a significant interaction between obesity and drug therapy (p = 0.019) with a better diastolic blood pressure response to calcium entry blockers in lean patients and to beta blockers in obese hypertensive patients.

CONCLUSION

Obesity affects the efficacy of metoprolol and isradipine in reducing blood pressure.