Is a series of blood pressure measurements by the general practitioner or the patient a reliable alternative to ambulatory blood pressure measurement? A study in general practice with reference to short-term and long-term between-visit variability.

We studied the reproducibility of a series of blood pressure measurements by general practitioner (GP) and patient in comparison with that of ambulatory blood pressure measurement (ABPM), with reference to short-term and long-term between-visit variability using a prospective, comparative diagnostic study. The study group was 88 potentially hypertensive primary care patients (initial systolic blood pressure [SBP] between 160 and 200 mm Hg or with diastolic blood pressure [DBP] between 95 and 115 mm Hg). ABPMs were measured on 2 separate days (at a 6 month interval). Two series of measurements by the doctor (at 1 to 6 month intervals), and the patient (at a 1 week interval) were measured. Mean differences and standard deviations of mean differences (SDD) between two successive series of measurements, and between two ABPMs were computed. The Wilcoxon signed-ranks test was used to compare these standard deviations. Mean initial office-blood pressures were 161 (SBP) and 102 (DBP) mm Hg. Long-term between-visit variability (measurements by GP) was larger than short-term between-visit variability: SDDs were 16 v 11 mm Hg (SBP), and 10 v 8 mm Hg (DBP). The differences in average SBP and DBP between successive ABPMs and between successive series of office measurements by GP and home measurements by patient were not statistically significant. Mean differences between two series of measurements by GP and patient, and between two ABPMs, were 0 +/- 1 mm Hg. SDDs between successive ABPMs and series of measurements by GP and patient ranged from 8 to 11 mm Hg (SBP), and were 6 mm Hg (DBP). No statistically significant differences were found between the SDDs of the studied measurement procedures (SBP and DBP). In our study the reproducibility of ambulatory blood pressure measurement was not found to be better than that of a series of four duplicate measurements by GP or patient. Long-term (6 months interval) between-visit variability was larger than the short-term (1 week interval) between-visit variability.