Curr Hypertens Rep (2014) 16:470 DOI 10.1007/s11906-014-0470-8
BLOOD PRESSURE MONITORING AND MANAGEMENT (G OGEDEGBE AND JA STAESSEN, SECTION EDITORS)
Cardiovascular Risk Stratification and Blood Pressure Variability on Ambulatory and Home Blood Pressure Measurement José Boggia & Kei Asayama & Yan Li & Tine Willum Hansen & Luis Mena & Rudolph Schutte
Published online: 6 August 2014 # Springer Science+Business Media New York 2014
Abstract Variability is a phenomenon attributed to most biological processes and is a particular feature of blood pressure (BP) that concerns many physicians regarding the clinical meaning and the impact on their clinical practice. In this review, we assessed the role of different indices of BP variability in cardiovascular risk stratification. We reviewed the indices of BP variability derived from ambulatory BP monitoring (day-to-night ratio, morning surge of BP, and short-term
This article is part of the Topical Collection on Blood Pressure Monitoring and Management J. Boggia Unidad de Hipertensión Arterial, Centro de Nefrología and Departamento de Fisiopatología, Universidad de la República, Montevideo, Uruguay
BP variability) and home BP measurement (standardized conventional BP measurement and self-BP measurement), and summarized our recent results with the intention to provide a clear message for clinical practice. Conclusion: BP variability, either derived from ambulatory BP measurement or home BP measurement does not substantially refine cardiovascular risk prediction over and beyond the BP level. Practitioners should be aware that BP level remains the main modifiable risk factor derived from BP measurement and contributes to improving the control of hypertension and adverse health outcomes. Keywords Hypertension . Blood pressure variability . Blood pressure monitoring . Epidemiology . Population science
Introduction K. Asayama Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan Y. Li Center for Vascular Evaluations Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China T. W. Hansen Steno Diabetes Center, Gentofte, Denmark L. Mena Departamento de Informática, Universidad Politécnica de Sinaloa, Mazatlan, Mexico R. Schutte Department of Physiology, Hypertension in Africa Research Team, North-West University, Potchefstroom, South Africa J. Boggia (*) Unidad de Hipertensión Arterial, Hospital de Clínicas Dr Manuel Quintela, Av Italia 2870 Piso 15 Sala 1 Of 13, 11600 Montevideo, Uruguay e-mail: [email protected]
As physicians, we are aware of the preponderance of BP level on cardiovascular risk stratification. However, the prognostic value of variability between repeated BP measurements, independent of the level of BP, continues to generate operational doubts in the practitioners. The concept of BP variability is extremely vague and spans the circadian variability (day-tonight variability and morning surge of BP), variation in shorter intervals of time (reading-to-reading variability), and variation between doctor’s office visits (visit-to-visit BP variability), among others. All these heterogeneous forms of BP variation indeed reflect different physiological phenomena with weak correlation between them [1]. In this review, we condensed our contributions from recent years from different and complementary perspectives of BP measurement. All reviewed studies had sufficient power, long follow-up duration, and a wide age range. The conclusions are based mainly on novel indices of BP variability, as assessed by 24-h ambulatory monitoring and self-measurement at home. The progress in healthcare systems and the adoption of healthy lifestyles,
470, Page 2 of 10
particularly quitting smoking, eating healthy, and being more physically active, results in reduced mortality rates. With such improvement in cardiovascular mortality, considering only fatal events might not accurately reflect cardiovascular risk. Our results, based on combined fatal and non-fatal cardiovascular and cerebrovascular events, are, therefore, the clearest and most elaborate estimation of cardiovascular risk.
Ambulatory Blood Pressure Day-to-Night Blood Pressure Variability Normally, the diurnal BP profile includes a 10 % to 20 % fall in BP during sleep, which is attenuated by physical inactivity, and which is mostly independent of an endogenous rhythm [2]. An abnormal circadian BP profile with a less marked decrease in nighttime BP level was related to a more frequent history of stroke, as demonstrated by O’Brien et al. in 1988 [3]. Subsequent studies of hypertensive cohorts [4–10] and populations [11–14] corroborated that a raised nocturnal BP predicted a higher rate of cardiovascular complications. However, several potential limitations warranted further clarification of the prognostic accuracy of the day vs. night ambulatory BP. Many studies considered only fatal outcomes [8, 9, 11, 12] or did not have the power to study cause-specific cardiovascular endpoints [8, 11, 12, 14]. Further, the night-to-day BP ratio was frequently dichotomized, and different definitions of dipping status and daytime and nighttime intervals were considered. Few reports formally compared the predictive value of BP at night over and beyond the daytime value. In 2007, we reported that risk estimates for fatal events, and fatal combined with non-fatal events, were independently associated with the daytime and nighttime BP level [15]. In continuous and categorical analyses, we investigated whether the night-to-day ratio of BP contained any prognostic information over and beyond the 24-h BP. In the context of the International Database on Ambulatory blood pressure monitoring in relation to Cardiovascular Outcomes (IDACO) [16], we analyzed 7,458 people, mean age 56.8 years, enrolled in prospective population studies in Denmark, Belgium, Japan, Sweden, Uruguay, and China. One SD elevation of the nighttime systolic BP and diastolic BP increased cardiovascular risk by approximately 20 %, even when adjusting for traditional risk factors, history of cardiovascular disease, antihypertensive treatment, and daytime BP. Daytime BP did not independently predict mortality outcomes, but was associated with the combination of fatal and non-fatal cardiovascular, coronary, and stroke events. Ten-year risk analysis showed that daytime and nighttime systolic BP were related to increased risk of cardiovascular events in untreated participants (Fig. 1, panel A). Antihypertensive drug treatment removed the significant association between cardiovascular events and
Curr Hypertens Rep (2014) 16:470
daytime BP, suggesting that hypertensive patients have a better control of BP during the day, but not at night. The night-to-day ratio of BP weights nighttime BP by daytime BP. Then, even in normotensive subjects, we can find a diminished or even inverted night-to-day ratio of BP. The important question we should address here is the following: What increases cardiovascular risk in my patients? Is it the BP level or the magnitude of BP change from day to night (night-to-day ratio), or both? In continuous analysis, the hazard ratio (HR) associated with 1 SD increase of the systolic night-to-day ratio of BP was not associated with cardiovascular mortality (Table 1). After adjustment for conventional risk factors, history of cardiovascular disease, antihypertensive treatment, and 24-h BP, the systolic nightto-day ratio of BP was not associated with any of the combined fatal and non-fatal events (Table 1). In categorical analysis, the HR associated with extreme decreased and reverse dipping vs. normal dipping showed an increasing risk from extreme to reverse dipping for mortality, but the results were inconsistent when considering fatal combined with non-fatal events. More recently [17], in a larger and more diverse database (8,711 individuals from 10 populations; mean age 54.8 years; 47.0 % women), we assessed the risk associated with isolated nocturnal hypertension and isolated daytime hypertension. Of these, 577 (6.6 %) untreated individuals had isolated nighttime hypertension (daytime BP
BLOOD PRESSURE MONITORING AND MANAGEMENT (G OGEDEGBE AND JA STAESSEN, SECTION EDITORS)
Cardiovascular Risk Stratification and Blood Pressure Variability on Ambulatory and Home Blood Pressure Measurement José Boggia & Kei Asayama & Yan Li & Tine Willum Hansen & Luis Mena & Rudolph Schutte
Published online: 6 August 2014 # Springer Science+Business Media New York 2014
Abstract Variability is a phenomenon attributed to most biological processes and is a particular feature of blood pressure (BP) that concerns many physicians regarding the clinical meaning and the impact on their clinical practice. In this review, we assessed the role of different indices of BP variability in cardiovascular risk stratification. We reviewed the indices of BP variability derived from ambulatory BP monitoring (day-to-night ratio, morning surge of BP, and short-term
This article is part of the Topical Collection on Blood Pressure Monitoring and Management J. Boggia Unidad de Hipertensión Arterial, Centro de Nefrología and Departamento de Fisiopatología, Universidad de la República, Montevideo, Uruguay
BP variability) and home BP measurement (standardized conventional BP measurement and self-BP measurement), and summarized our recent results with the intention to provide a clear message for clinical practice. Conclusion: BP variability, either derived from ambulatory BP measurement or home BP measurement does not substantially refine cardiovascular risk prediction over and beyond the BP level. Practitioners should be aware that BP level remains the main modifiable risk factor derived from BP measurement and contributes to improving the control of hypertension and adverse health outcomes. Keywords Hypertension . Blood pressure variability . Blood pressure monitoring . Epidemiology . Population science
Introduction K. Asayama Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan Y. Li Center for Vascular Evaluations Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China T. W. Hansen Steno Diabetes Center, Gentofte, Denmark L. Mena Departamento de Informática, Universidad Politécnica de Sinaloa, Mazatlan, Mexico R. Schutte Department of Physiology, Hypertension in Africa Research Team, North-West University, Potchefstroom, South Africa J. Boggia (*) Unidad de Hipertensión Arterial, Hospital de Clínicas Dr Manuel Quintela, Av Italia 2870 Piso 15 Sala 1 Of 13, 11600 Montevideo, Uruguay e-mail: [email protected]
As physicians, we are aware of the preponderance of BP level on cardiovascular risk stratification. However, the prognostic value of variability between repeated BP measurements, independent of the level of BP, continues to generate operational doubts in the practitioners. The concept of BP variability is extremely vague and spans the circadian variability (day-tonight variability and morning surge of BP), variation in shorter intervals of time (reading-to-reading variability), and variation between doctor’s office visits (visit-to-visit BP variability), among others. All these heterogeneous forms of BP variation indeed reflect different physiological phenomena with weak correlation between them [1]. In this review, we condensed our contributions from recent years from different and complementary perspectives of BP measurement. All reviewed studies had sufficient power, long follow-up duration, and a wide age range. The conclusions are based mainly on novel indices of BP variability, as assessed by 24-h ambulatory monitoring and self-measurement at home. The progress in healthcare systems and the adoption of healthy lifestyles,
470, Page 2 of 10
particularly quitting smoking, eating healthy, and being more physically active, results in reduced mortality rates. With such improvement in cardiovascular mortality, considering only fatal events might not accurately reflect cardiovascular risk. Our results, based on combined fatal and non-fatal cardiovascular and cerebrovascular events, are, therefore, the clearest and most elaborate estimation of cardiovascular risk.
Ambulatory Blood Pressure Day-to-Night Blood Pressure Variability Normally, the diurnal BP profile includes a 10 % to 20 % fall in BP during sleep, which is attenuated by physical inactivity, and which is mostly independent of an endogenous rhythm [2]. An abnormal circadian BP profile with a less marked decrease in nighttime BP level was related to a more frequent history of stroke, as demonstrated by O’Brien et al. in 1988 [3]. Subsequent studies of hypertensive cohorts [4–10] and populations [11–14] corroborated that a raised nocturnal BP predicted a higher rate of cardiovascular complications. However, several potential limitations warranted further clarification of the prognostic accuracy of the day vs. night ambulatory BP. Many studies considered only fatal outcomes [8, 9, 11, 12] or did not have the power to study cause-specific cardiovascular endpoints [8, 11, 12, 14]. Further, the night-to-day BP ratio was frequently dichotomized, and different definitions of dipping status and daytime and nighttime intervals were considered. Few reports formally compared the predictive value of BP at night over and beyond the daytime value. In 2007, we reported that risk estimates for fatal events, and fatal combined with non-fatal events, were independently associated with the daytime and nighttime BP level [15]. In continuous and categorical analyses, we investigated whether the night-to-day ratio of BP contained any prognostic information over and beyond the 24-h BP. In the context of the International Database on Ambulatory blood pressure monitoring in relation to Cardiovascular Outcomes (IDACO) [16], we analyzed 7,458 people, mean age 56.8 years, enrolled in prospective population studies in Denmark, Belgium, Japan, Sweden, Uruguay, and China. One SD elevation of the nighttime systolic BP and diastolic BP increased cardiovascular risk by approximately 20 %, even when adjusting for traditional risk factors, history of cardiovascular disease, antihypertensive treatment, and daytime BP. Daytime BP did not independently predict mortality outcomes, but was associated with the combination of fatal and non-fatal cardiovascular, coronary, and stroke events. Ten-year risk analysis showed that daytime and nighttime systolic BP were related to increased risk of cardiovascular events in untreated participants (Fig. 1, panel A). Antihypertensive drug treatment removed the significant association between cardiovascular events and
Curr Hypertens Rep (2014) 16:470
daytime BP, suggesting that hypertensive patients have a better control of BP during the day, but not at night. The night-to-day ratio of BP weights nighttime BP by daytime BP. Then, even in normotensive subjects, we can find a diminished or even inverted night-to-day ratio of BP. The important question we should address here is the following: What increases cardiovascular risk in my patients? Is it the BP level or the magnitude of BP change from day to night (night-to-day ratio), or both? In continuous analysis, the hazard ratio (HR) associated with 1 SD increase of the systolic night-to-day ratio of BP was not associated with cardiovascular mortality (Table 1). After adjustment for conventional risk factors, history of cardiovascular disease, antihypertensive treatment, and 24-h BP, the systolic nightto-day ratio of BP was not associated with any of the combined fatal and non-fatal events (Table 1). In categorical analysis, the HR associated with extreme decreased and reverse dipping vs. normal dipping showed an increasing risk from extreme to reverse dipping for mortality, but the results were inconsistent when considering fatal combined with non-fatal events. More recently [17], in a larger and more diverse database (8,711 individuals from 10 populations; mean age 54.8 years; 47.0 % women), we assessed the risk associated with isolated nocturnal hypertension and isolated daytime hypertension. Of these, 577 (6.6 %) untreated individuals had isolated nighttime hypertension (daytime BP
