HOME SELF BLOOD-PRESSURE MEASUREMENT IN GENERAL-PRACTICE - THE SMART STUDY

The SMART study (Self-Measurement for the Assessment of the Response t o Trandolapril) was performed in general practice and enrolled 1710 pa tients in order to assess on a large scale the feasibility and informa tive value of self-measurement of blood pressure at home (SMBP), defin e home blood pressure (BP) levels in comparison to office readings, an d determine the number of home measurements necessary to provide an ac curate and precise BP value. After a 2-week washout period, patients w ith office diastolic blood pressure within the range 95 to 119 mm Hg r eceived 2 mg trandolapril once daily in the morning for 4 weeks. Four days of SMBP were performed both at the end of the washout period and the end of the treatment period, with an automatic printer-equipped os cillometric device (A&D UA751). The first day values were not analyzed . Thus, the maximum number of BP measurements obtained per patient and per period was 18. Four hundred and twenty-four patients (25%) did no t perform any measurements. One thousand one hundred and nine patients (65%) performed at least 4 measurements. Among them, 619 (36%) correc tly performed all 18 measurements. A preference for digits 0 and 5 was detected in physicians' measurements (three consecutive values, durin g a single office visit). This digit preference was not found with the semiautomatic device. When the number of measurements selected for an alysis was increased from 1 to 18, in the 604 patients who provided al l recordings and fullfilled all protocol criteria, the standard deviat ion of the mean BP of the cohort was reduced by 17% for SEP and by 23% for DBP. Eighty-five percent of this reduction was already achieved b y six home measurements taken at random. BP was significantly lower at home than at the office by 13 +/- 15 mm Hg for systolic BP (SEP), and 8 +/- 10 mm Hg for diastolic BP (DBP). This difference was independen t of age, more marked in women (P <.001 for SEP and P <.05 for DBP), a nd had a Gaussian distribution. Under treatment, office SBP/DBP decrea sed from 166.4 +/- 14.8/101.4 +/- 5.7 mm Hg to 144.7 +/- 14.2/86.1 +/- 8.3 mm Hg, while SMBP decreased from 153.2 +/- 17.8/93.8 +/- 10.1 mm Hg to 139.4 +/- 16.4/85.1 +/- 9.5 mm Hg (all P < .0001). A major aim i n research studies and individual care is to reduce BP measurements va riability. This study demonstrates the ability to evaluate baseline SM BP level in two-thirds of patients previously unfamiliar with the meth od, the ability to evaluate treatment effect in about one-half of the patients, the improvement in the measurement precision obtained with t he repetition of measures (at least six home measurements), and the ab sence of bias of SMBP as compared to office measurements.