Standardization of Blood Pressure Measurement in a Geriatric Outpatient Clinic

To the Editor: Up to 30% of community-dwelling older people have hypertension.1,2 Randomized, controlled trials confirm the benefit of tight blood pressure control, but clinicians must transfer this evidence into daily practice.3,4 It is often difficult for geriatricians to judge the reliability of readings when they encounter patients with fluctuating blood pressure in clinic visits. A clinical study was performed to examine the effect of adopting a standardized blood pressure measuring protocol on the variation of blood pressure readings in a geriatric outpatient clinic that sees patients at intervals from 6 to 12 weeks. We hypothesized that by improving the quality of clinic blood pressure measurement through the adoption of this protocol we could reduce the variation of observed blood pressure in elderly patients attending the clinic. The protocol was introduced to the clinic in February 2001. Essential elements included use of the Colin BP-203RVII automatic blood pressure machine (Colin Medical Instruments Corp., San Antonio, TX), written instructions with picture demonstration for patients to follow, blood pressure measurement to be performed on every patient before they entered the consultation room, first blood pressure reading to be taken at least 15 minutes after patient's arrival, and a second measurement of blood pressure taken if first systolic blood pressure was 160 mmHg or greater or diastolic blood pressure was 95 mmHg or greater. The two measurements were to be taken at least 15 minutes apart. The study was divided into three periods: Period 1 (February 1, 2000 through July 31, 2000), Period 2 (August 1, 2000 through January 31, 2001), and Period 3 (March 1, 2001 through August 31, 2001). February 2001 served as the pilot period for the protocol, then Period 3 was immediately afterwards. Period 2 was immediately before the protocol and Period 1 was the same season as Period 3 but 1 year before, to check whether there was any seasonal effect. Subjects with regular follow-up in the clinic from February 1, 2000, to August 31, 2001, who could provide three blood pressure readings that were at least 6 weeks apart in each of the study periods were recruited. Those who suffered acute medical problems during the study period were excluded. The variance of blood pressures of each individual was used as a measure of variability. The variances of the serial blood pressures obtained in each period were compared. Factors associated with blood pressure variation were examined using multiple regression analysis. A survey was conducted during the study period to assess the protocol compliance. One hundred three patients entered the analysis. The mean age was 77.7 (range 66–100). Of these, 56.3% were female. The most common medical diagnosis was hypertension (50.5%), followed by atrial fibrillation (47.6%) and diabetes mellitus (38.8%). Adherence to the protocol was 73.8%. After adopting the standardized protocol compared with the same period 1 year before, no significant difference was found in systolic, diastolic, or mean blood pressure variance before and after the protocol implementation, with the exception of a tendency toward lower systolic blood pressure variance (Table 1). Female sex and the total number of drugs received were independent predictors of blood pressure variability in multivariate analysis. The study found that, with a follow-up interval of 6 to 12 weeks, standardizing the blood pressure measurement procedures did not reduce the observed variation of blood pressure in geriatric patients. Instead of focusing on clinic policy, geriatricians should consider other alternatives for blood pressure monitoring, such as home self-monitoring if patients with high blood pressure variation were encountered. Further evaluations on the effect of alternative blood pressure measurement strategies in clinic practices are required. The full story on blood pressure monitoring will also require cost-effectiveness measures for different blood pressure measurement strategies.