Long term reproducibility of ambulatory blood pressure monitoring.
The long term reproducibility of ambulatory blood pressure measurements was evaluated over two 24 h recordings made under identical conditions 2 years apart in 20 normotensive and 13 essential hypertensive patients not receiving antihypertensive treatment. There was excellent agreement between the mean 24 h values of blood pressure as well as for the day time and night time means. The standard deviation of the differences was half that of casual determinations. On the other hand, the reproducibility of the mean hourly values was comparable to that of casual measurements. The reproducibility of the white coat effect was poor, as assessed by the difference between blood pressure on fitting the device and the mean day time value. These results indicate that the short term reproducibility of ambulatory blood pressure is maintained over the long term.