Assessment of long-term antihypertensive treatment by clinic and ambulatory blood pressure: data from the European Lacidipine Study on Atherosclerosis

Objectives Information on the features of long-term modifications of clinic and 24-h ambulatory blood pressure (ABP) by treatment is limited. The present study aimed to address this issue. Methods Ambulatory BP monitoring and clinic BP (CBP) measurements were performed at baseline and at yearly intervals over a 4-year follow-up period in 1523 hypertensives (56.1 7.6 years) randomized to treatment with lacidipine or atenolol in the European Lacidipine Study on Atherosclerosis (ELSA). Results CBP was always greater than ABP, while reductions in all BP values (greater for CBP than for ABP) were on average maintained throughout 4 years, CBP changes showing limited relationship with ABP changes (r = 0.14-0.27). BP reductions by treatment during daytime and night-time were correlated ( r =0.63 - 0.73). BP normalization was achieved in a greater percentage of patients for CBP (41.7%) than for ABP (25.3%), with systolic BP control being always less common than diastolic BP control. BP normalization was more frequent at single yearly visits than throughout the 4 years. Twenty-four-hour BP variability was reduced by treatment over 4 years in absolute but not in normalized units. Conclusions The present study provides the best evidence available on long-term effect of antihypertensive treatment on both ABP and CBP. On average, ABP was sustainedly reduced by treatment throughout the follow-up period, but 24-h BP was more difficult to control than CBP. In several patients, ABP control was unstable between visits, the percentage of patients under control over 4 years being much less than that of those controlled at each year. Treatment induced a reduction in absolute but not in normalized BP variability estimates. This has clinical implications because of the prognostic importance of ABP mean values and variability.