High 24-h ambulatory blood pressure (ABP) variability is associated with poor cardiovascular outcomes. We analysed a large ABP monitoring database containing data from hypertensive patients treated with telmisartan/amlodipine combination or various monotherapies with the aim of quantifying the 24-h distribution of blood pressure (BP) reduction by treatment through the smoothness index and of developing and testing a new treatment-on-variability index (TOVI) to quantify the effects of treatment on both mean BP and BP variability.
ABP data were pooled from 10 studies (N = 4294) with a median follow-up of 60 days. Smoothness index was calculated by dividing the mean of treatment-induced hourly BP reductions by its SD. TOVI was calculated as the ratio of the mean of hourly BP reductions to weighted 24-h BP SD (weighted mean of daytime and night-time SDs) under treatment.
The SBP/DBP smoothness index and TOVI values of telmisartan/amlodipine combination were significantly (P < 0.0001) higher (smoothness index: 1.81/1.51; TOVI: 2.71/2.13) compared with telmisartan 80 mg (smoothness index: 1.12/0.90; TOVI: 1.55/1.23), amlodipine 10 mg (smoothness index: 1.33/1.09; TOVI: 2.09/1.58), valsartan 160 mg (smoothness index: 1.01/0.81; TOVI: 1.35/1.07), ramipril 10 mg (smoothness index: 0.83/0.63; TOVI: 1.11/0.87) and placebo (smoothness index: 0.23/0.18; TOVI: 0.34/0.30), indicating a smoother 24-h BP reduction profile (higher smoothness index) as well as the achievement of significantly lower and smoother BP levels over 24 h (higher TOVI) with the combination.
As compared with various monotherapies, the telmisartan/amlodipine combination was associated with a smoother BP reduction over 24 h and with a more favourable balance between mean 24-h BP reduction and the degree of BP variability on treatment, reflecting both its effectiveness in lowering BP levels and its longer duration of action. The agreement between smoothness index and TOVI demonstrates that they are similarly effective in the differentiation of antihypertensive treatments, although providing conceptually different information, the clinical relevance of which needs to be tested by ad-hoc outcome studies.