Reliability of self-reported blood pressure measurements

Background: Home blood pressure (BP) monitoring improves BP control, but it is unknown whether patients accurately report home BP readings to their physician. This study compared self-reported with electronically stored home BP and heart rate (HR) readings and evaluated this agreement in patients with controlled vs uncontrolled hypertension. Methods: A single-blind, randomized clinical trial was conducted in an ambulatory managed care population. Subjects were identified by hypertension-related codes from the International Classification of Diseases, Ninth Revision (401.0, 401.1, and 401.9). Subjects recorded systolic BP (SBP), diastolic BP (DBP), and HR 3 times daily for 1 week by means of a digital BP monitor. Subjects were unaware that the monitor electronically stored results. Results: Thirty subjects were enrolled (29 complete data sets); their mean age (+/-SD) was 56 +/- 9 years, and 15 (52%) were women. Sixty-eight percent of subject-recorded SEP, DBP, and HR measurements were identical to electronically stored results. Twenty percent of recorded SBPs and 17% of recorded DBPs differed from stored SBP and DBP by more than 10 mm Hg. Erroneous reporting was evident in 9% of uncontrolled vs 4% of controlled SBPs (P < .001). Similarly, 21% of uncontrolled and 4% of controlled DBPs were erroneously reported (P < .001). In cases where the stored HR exceeded 100 beats/min, 43% of HR readings were recorded as 100 beats/min or less (P < .001). Conclusions: Most self-reported BP and HR readings were identical to electronically stored measurements. However, erroneous reporting occurred significantly more often in cases of uncontrolled BP and HR, which may misguide physicians in the optimal treatment of their patients with hypertension.