DOES IT MATTER WHETHER AMBULATORY BLOOD-PRESSURE IS RECORDED DURING AWORK DAY OR A NONWORK DAY

Objective To compare ambulatory blood pressure recorded during a work day with that recorded during a non-work day. Design A cross-over rand omized study in middle-aged treated hypertensives and normotensives. S etting Primary health care. Subjects Forty treated hypertensives (20 m en) and 40 normotensives (20 men). Main outcome measure Individual dif ference between ambulatory blood pressures recorded during a work day and during a non-work day. Results The systolic/diastolic blood pressu re of the hypertensives was 2/3 (7/5) [mean (SD)] mmHg higher and that of the normotensives 3/3 (5/4) mmHg higher during the work day 24 h m onitoring. The blood pressure of the normotensives showed a statistica lly significant difference between the two monitoring periods both for systolic and for diastolic blood pressure during 24 h and daytime. Th e corresponding comparison in the hypertensives showed a significant d ifference only for diastolic blood pressure. During night-time there w as no statistically significant difference between the two monitoring periods, neither in the hypertensives nor in the normotensives. Indivi dual comparisons revealed large variations between the two monitoring periods in many subjects. Among the hypertensives the percentage of su bjects with a systolic blood pressure difference >10 mmHg (higher or l ower during their work day monitoring period) was 20% during 24 h, 32. 5% during daytime and 15% during night-time. The corresponding values for a diastolic blood pressure difference >5 mmHg were 40% during 24 h , 32.5% during daytime and 40% during night-time. Among the normotensi ves the corresponding values for systolic/diastolic blood pressure dif ferences between the two monitoring periods were 5/27.5% during 24 h, 5/27.5% during daytime and 2.5/27.5% during night-time. Conclusion Amb ulatory blood pressure recorded during a work day might differ from th at recorded during a non-work day. It is important to be aware of this fact when evaluating individual blood pressure graphs, although the i mportance of this for the development of organ damage is not known, To perform more than a single 24 h blood pressure monitoring can be of v alue to obtain a better idea of the blood pressure variability of a pa tient.