Evaluating 24-h antihypertensive efficacy by the smoothness index: a meta-analysis of an ambulatory blood pressure monitoring database

OBJECTIVE: The aim of this meta-analysis was to compare the 24-h antihypertensive efficacy of different treatments using the smoothness index. METHODS: Data were taken from the telmisartan ambulatory blood pressure monitoring (ABPM) clinical programme. Eleven clinical trials that randomized mild-to-moderate hypertensive patients to treatment with telmisartan 40/80 mg, losartan 50 mg, valsartan 80/160 mg, ramipril 10 mg, amlodipine 5 mg monotherapy, or with an angiotensin receptor blocker (ARB) and hydrochlorothiazide (HCTZ) 12.5/25 mg, were included. Treatment duration ranged from 4 to 14 weeks. The smoothness index was calculated according to the published formula. RESULTS: Altogether, 5188 patients were included (65% men; 52% were using telmisartan as monotherapy or in combination with HCTZ). Telmisartan 80 mg had a higher smoothness index than losartan, valsartan or ramipril (P < 0.05), and was comparable with amlodipine. All combination therapies had a higher smoothness index than monotherapy; the largest value was observed with telmisartan 80 mg and HCTZ 12.5 mg. Overall, the smoothness index was lower in men, older patients, black patients, smokers and in those with lower baseline blood pressure (P < 0.05). CONCLUSION: The smoothness index was affected by age, race, sex, behavioural and haemodynamic factors. It was also able to differentiate the 24-h blood pressure effects of antihypertensive drugs, with telmisartan and amlodipine achieving the highest values, possibly because of their long plasma half-lives. All combination therapies had a higher smoothness index than monotherapy. An understanding of the relative effects of different antihypertensives on the smoothness index may help to differentiate their effectiveness in reducing blood pressure-related cardiovascular risk.