Reproducibility and cost of blood pressure self-measurement using the ‘Loaned Self-measurement Equipment Model’

OBJECTIVE: To determine the reproducibility and the cost of the Loaned Self-measurement Equipment Model for blood pressure. SUBJECTS: Seventy-five subjects with non-complicated essential hypertension, having an average age of 56.2 +/- 11 years, were evaluated. METHODS: The Loaned Self-measurement Equipment Model consists of a set of sphygmomanometers belonging to the clinic, loaned to patients for 3-day periods for them to carry out 27 readings, and then returned. Using a mercury sphygmomanometer, a nurse carried out office blood pressure readings during two visits. A month later, the same procedure was repeated under the same clinical conditions. The agreement between studies was assessed by correlation coefficients, coefficients of variation and standard deviation of the differences (SDD). RESULTS: The office blood pressure was 147 +/- 17/89 +/- 12 mmHg during visit A, and 145 +/- 16/88 +/- 11 mmHg during visit B. The self-measurement blood pressure was 139 +/- 16/84 +/- 10 mmHg during the first visit, and 136 +/- 15/84 +/- 11 mmHg during the second visit. In neither of the cases were the differences statistically significant. The correlation coefficients for the office and self-measurement systolic blood pressure were statistically significant (P = 0.018), while those for the diastolic blood pressure were not statistically significant. The SDD for self-measurement systolic blood pressure was 10.7, compared to 15.0 for the office blood pressure (P < 0.01). The comparison in the case of diastolic blood pressure was not significant. The cost of each loan was $5.85 (US dollars). CONCLUSIONS: The Loaned Self-measurement Equipment Model has a good short-term reproducibility, and the cost is reasonable.