Factors influencing the accuracy of home blood pressure measurement.
BACKGROUND: Hypertension is a common disorder, affecting approximately 50 million Americans. Because many people have this disorder and its sequela, it is important not only to detect hypertension but also to monitor adequacy of control. Over the past few years, blood pressure monitoring devices (BPMDs) have become available for individuals to measure their blood pressure (BP) in the convenience of their home. These instruments are touted as being accurate. METHODS: We conducted a study with volunteers who use BPMDs to see how they are used and to assess their accuracy. A BP reading was considered accurate if the differences between the volunteers' and technicians' systolic and diastolic readings were both 10 mm Hg or less. RESULTS: Of 91 patients, 31 (34%) obtained inaccurate readings. The inaccuracy could not be attributed to the type of the instrument, the cost of the instrument, the educational level of the user, or the age of the instrument. CONCLUSIONS: This study shows, despite other studies purporting accuracy, that a significant number of inaccurate readings are obtained by patients using BPMDs. Supervision of their use needs to be incorporated into the physician follow-up to ensure that there is a reasonable correlation between values obtained using the mercury sphygmomanometer and the BPMD.