Study Overview
Objective. To determine the prevalence of hypotension using both clinic and ambulatory blood pressure monitoring (ABPM) in treated hypertensive patients and the factors associated with its presence.
Design. Registry-based study.
Setting and participants . Researchers studied patients in the Spanish Society of Hypertension ABPM Registry, which was established to evaluate the utility of the wider use of ABPM with the distribution of >1000 ambulatory BP monitors for routine use by primary care physicians and physicians from specialist units across Spain. The registry continues to expand since the first patient was recruited in June 2004. In June 2015, a total of 135,500 hypertensive patients were in the registry.
Measurements. Blood pressure readings in the clinic were taken according to current recommendations, with the patients in a seated position and their backs supported, after a 5-minute rest, using calibrated sphygmomanometers or validated automatic devices. The visit BP was the average of 2 separate readings. Validated devices (Spacelabs) were used for ABPM, which was performed during a working day with measurements taken every 30 minutes. Patients were told to keep their activity normal and to extend the arm without any movement during BP measurements. ABPM was considered successful in ≥ 80% systolic and diastolic BP valid readings. Patients were classified into 3 categories: hypotension, adequate BP control, or poor BP control for each type of blood pressure (office, daytime, nighttime, and 24-hour). The definitions for hypotension for each BP type were mainly based of the PROVE IT-TIMI study, ie, < 110 and/or 70 mm Hg for office, < 105 and/or 65 mm Hg for daytime ABPM, < 90 and or 50 mm Hg for nightime ABPM, and < 100 and/or 60 mm Hg for 24-hr ABPM.
Results. Of the 135,500 patients in the registry, only data from treated hypertensive patients were analyzed ( n = 70,997). Mean age was 61.8 ± 12.8 years and 52.5% were men. The prevalence of hypotension was 8.2% with office BP, 12.2% with daytime ABPM, 3.9% with nightime ABPM, and 6.8% with 24-hour ABPM. Low diastolic BP values were responsible for the majority of hypotension. More than 68% of patients with hypotension detected with ABPM did not have hypotension according to office BP. Patients with hypotension were older, more likely to be female, and more likely to have high pulse pressue, lower heart rate, ischemic heart disease, and renal insufficiency. They were also more likely to be taking 3 or more drugs for hypertension.
Conclusion. The prevalence of hypotension is relatively high in treated hypertensive patients, and two-thirds are not identified with office BP measurement. Prevalence was higher in patients who were very elderly or with coronary or renal disease.
Commentary
Hypertension is a major public health concern worldwide [1]. In 2011–12 among US adults with hypertension, only 51.9% had their blood pressure controlled [2]. High blood pressure can effectively be reduced with antihypertensive treatment, and efforts are needed to improve clinical management of hypertension. However, excessive BP reduction may lead to patient harm.
In this study, researchers aimed to determine the prevalence of hypotension using both clinic and ABPM in hypertensive-treated patients and the factors associated with its presence, using descriptive statistics and multivariate analysis. The results highlight the need for health care providers to be aware of the individual response to antihypertensives in patients with high blood pressure and to individualize treatment to avoid complications of hypotension. A strength of this study was it large sample size.
Adherence to treatment recommendations was not a variable taken into consideration for this study and could be considered a confounder. Diet and behavioral interventions can have a significantly beneficial effect on hypertension and can reduce the need for drug therapy [3]. If patients were highly engaged and adopted lifestyle habits that can contribute to better blood pressure levels along with taking prescribed medications, this could have contributed to levels of hypotension.
Hypotension among hypertensive patients can be difficult to identify during clinical consultations due the “white coat effect.” This syndrome is characterized by a peak of high blood pressure caused by the stress of the individual in the presence of a healthcare provider or in a stressful medical environment [4]. This study showed that more than half of the patients in the sample with detected hypotension in the ABPM did not show hypotension during consultation at the medical office. This finding highlights the challenge in identifying hypotension and making adjustments to antihypertensive medication regimens as needed.
Women, patients with low body weight, and elderly patients were the groups more likely to develop hypo-tension. Thus, strategies specifically targeting these vulnerable groups are required. As suggested by the authors of this study, further longitudinal research is needed in order to identify gaps in the state of science in regards this topic and changes in the prevalence this population. The replication of this study in different populations is also encouraged.
Applications for Clinical Practice
The prevalence of hypotension is relatively high and may not be detected during office BP measurement. In patients with a higher risk of hypotension, such as the elderly those with cardiovascular disease, the use of ABPM should be considered.
—Paloma Cesar de Sales, BS, RN, MS