Comparison of three blood pressure measurement methods for the evaluation of two antihypertensive drugs: feasibility, agreement, and reproducibility of blood pressure response

Our objective was to compare three different methods of blood pressure measurement through the results of a controlled study aimed at comparing the antihypertensive effects of trandolapril and losartan. Two hundred and twenty-nine hypertensive patients were randomized in a double-blind parallel group study. After a 3-week placebo period, they received either 2 mg trandolapril or 50 mg losartan once daily for 6 weeks. At the end of both placebo and active treatment periods, three methods of blood pressure measurement were used: a) office blood pressure (three consecutive measurements); b) home self blood pressure measurements (SBPM), consisting of three consecutive measurements performed at home in the morning and in the evening for 7 consecutive days; and c) ambulatory blood pressure measurements (ABPM), 24-h BP recordings with three measurements per hour. Of the 229 patients, 199 (87%) performed at least 12 valid SBPM measurements during both placebo and treatment periods, whereas only 160 (70%) performed good quality 24-h ABPM recordings during both periods (P< .0001). One hundred-forty patients performed the three methods of measurement well. At baseline and with treatment, agreement between office measurements and ABPM or SBPM was weak. Conversely, there was a good agreement between ABPM and SBPM. The mean difference (SBP/DBP) between ABPM and SBPM was 4.6 ± 10.4/3.5 ± 7.1 at baseline and 3.5 ± 10.0/4.0 ± 7.0 at the end of the treatment period. The correlation between SBPM and ABPM expressed by the r coefficient and the P values were the following: at baseline 0.79/0.70 (< 0.001/< .0001), with active treatment 0.74/0.69 (0.0001/.0001). Hourly and 24-h reproducibility of blood pressure response was quantified by the standard deviation of BP response. Compared with office blood pressure, both global and hourly SBPM responses exhibited a lower standard deviation. Hourly reproducibility of SBPM response (10.8 mm Hg/6.9 mm Hg) was lower than hourly reproducibility of ABPM response (15.6 mm Hg/11.9 mm Hg). In conclusion, SBPM was easier to perform than ABPM. There was a good agreement between these two methods whereas concordance between SBPM or ABPM and office measurements was weak. As hourly reproducibility of SBPM response is better than reproducibility of both hourly ABPM and office BP response, SBPM seems to be the most appropriate method for evaluating residual antihypertensive effect.