This cohort study assesses the national prevalence of masked asleep hypertension among US adults.
Key Points
Question
What is the national prevalence of masked asleep hypertension among US adults?
Findings
This cohort study combined data from 3000 participants with 24-hour ambulatory blood pressure monitoring and data from 17 969 participants in the 2011-2016 National Health and Nutrition Examination Survey without ambulatory blood pressure monitoring. An estimated 22.7% (53.7 million) of US adults have masked asleep hypertension and 13.3% (31.5 million) have isolated masked asleep hypertension, using 2017 American College of Cardiology–American Heart Association guideline blood pressure thresholds.
Meaning
These findings suggest that the prevalence of masked asleep hypertension is high among US adults; data are needed on the cardiovascular risk reduction benefits of treating asleep hypertension.
Abstract
Importance
High blood pressure (BP) during sleep (asleep blood pressure) is associated with an increased risk of cardiovascular disease, but a national prevalence estimate of masked asleep hypertension (high BP while sleeping but without high BP measured in the clinic [clinic BP]) for the United States is lacking.
Objectives
To estimate the prevalence of masked asleep hypertension among US adults by using BP thresholds from the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) and the 2017 American College of Cardiology–American Heart Association (ACC-AHA) BP guidelines.
Design, Setting, and Participants
This cohort analysis pooled data from 3000 participants in 4 US population-based studies that conducted 24-hour ambulatory BP monitoring (ABPM) and 17 969 participants in the 2011-2016 National Health and Nutrition Examination Survey (NHANES) without ABPM. Masked asleep hypertension status in NHANES was imputed using a 2-stage multiple imputation process. Data were collected from 2000 to 2016 and analyzed from March 4, 2019, to June 29, 2020.
Main Outcomes and Measures
High clinic BP was defined as clinic systolic BP (SBP)/diastolic BP (DBP) of at least 140/90 mm Hg using JNC7 and at least 130/80 mm Hg using 2017 ACC-AHA guidelines. High asleep BP was defined as mean asleep SBP/DBP of at least 120/70 mm Hg for JNC7 and at least 110/65 mm Hg for the 2017 ACC-AHA guidelines. Masked asleep hypertension was defined as high asleep BP without high clinic BP.
Results
For the 3000 pooled cohort participants, the mean (SD) age was 52.0 (12.0) years, and 62.6% were women. For the 17 969 NHANES participants, the mean (SD) age was 46.7 (17.5) years, and 51.8% (weighted) were women. The estimated prevalence of masked asleep hypertension among US adults was 18.8% (95% CI, 16.7%-20.8%; 44.4 million US adults) using the JNC7 guideline and 22.7% (95% CI, 20.6%-24.8%; 53.7 million US adults) using the 2017 ACC-AHA guideline criteria. The prevalence of masked asleep hypertension was higher among older adults (aged ≥65 years, 24.4% [95% CI, 20.7%-28.0%]), men (27.0% [95% CI, 24.1%-29.9%]), non-Hispanic Black individuals (28.7% [95% CI, 25.4%-32.0%]), those who were taking antihypertensives (24.4% [95% CI, 21.1%-27.8%]), those who had masked daytime hypertension (44.7% [95% CI, 40.1%-49.3%]), and those with diabetes (27.6% [95% CI, 23.5%-31.8%]), obesity (24.3% [95% CI, 21.8%-26.9%]), or chronic kidney disease (21.5% [95% CI, 17.3%-25.6%]) using the 2017 ACC-AHA guideline. An estimated 11.9% of US adults (28.2 million) had isolated masked asleep hypertension (masked asleep hypertension but without high awake BP) using JNC7 guideline criteria, as did an estimated 13.3% (31.5 million) using 2017 ACC-AHA guideline criteria.
Conclusions and Relevance
These findings suggest that the prevalence of masked asleep hypertension is high among US adults. Data are needed on the cardiovascular risk reduction benefits of treating asleep hypertension.
Introduction
Ambulatory blood pressure monitoring (ABPM) is recommended by the 2017 American College of Cardiology–American Heart Association (ACC-AHA) blood pressure (BP) guideline to confirm a diagnosis of hypertension based on BP measurements obtained in the clinic (clinic BP).1 Ambulatory BP monitoring can also identify BP phenotypes not detected using clinic measurements alone, including asleep hypertension.1 Asleep hypertension, defined as high BP while sleeping, with or without high clinic BP, is associated with an increased risk of cardiovascular disease.2,3,4 However, most large US population-based cohorts and US national health surveys have not performed ABPM, and a national estimate for asleep hypertension is currently lacking.5
The primary objective of this study was to estimate the national prevalence of masked asleep hypertension (high asleep BP without high clinic BP) among US adults, defined according to BP thresholds established by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) and the 2017 ACC-AHA BP guidelines.1,6 We focused on masked asleep hypertension because individuals with this phenotype do not have high clinic BP and will not have their high BP detected by measurements taken in the clinic. We assembled a pooled cohort of participants from the following 4 studies with 24-hour ABPM: (1) Coronary Artery Risk Development in Young Adults,7 (2) Jackson Heart Study,8 (3) Masked Hypertension Study,9 and (4) Improving the Detection of Hypertension Study.10 We then combined the pooled cohort with participants in the 2011-2016 National Health and Nutrition Examination Survey (NHANES), in whom 24-hour ABPM was not collected, to impute masked asleep hypertension status in US adults.
Methods
Study Population
Details of the design of each study cohort are reported in the eMethods in the Supplement. For the current analysis, we only included individuals from the pooled cohort with 24-hour ABPM data (eFigure in the Supplement). We excluded participants with less than 10 awake or less than 5 asleep BP measurements because they did not meet the International Database of Ambulatory BP in relation to Cardiovascular Outcomes criteria for a complete ABPM.11 The final sample size was 3000 participants. All study protocols were approved by the institutional review boards at participating institutions and all participants provided written informed consent. We also combined data from the 2011-2012, 2013-2014, and 2015-2016 NHANES and included 17 969 NHANES participants at least 18 years of age with clinic systolic BP (SBP) and diastolic BP (DBP) measurements for the analysis. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.
Clinical Data Collection and Asleep Hypertension
Details of data collection are reported in the eMethods in the Supplement; data for the present analyses were collected from 2000 to 2016. High clinic BP was defined by JNC7 as mean clinic SBP/DBP of at least 140/90 mm Hg and by the 2017 ACC-AHA BP guideline as mean clinic SBP/DBP of at least 130/80 mm Hg. High awake BP was defined by JNC7 as mean awake SBP/DBP of at least 135/85 mm Hg and by the 2017 ACC-AHA guideline as mean awake SBP/DBP of at least 130/80 mm Hg. The asleep BP threshold according to JNC7 was at least 120/75 mm Hg; however, guidelines and scientific statements have since adopted asleep BP thresholds of at least 120/70 mm Hg to correspond to clinic-measured BP of at least 140/90 mm Hg.12,13 Therefore, in the present study, high asleep BP was defined as mean asleep SBP/DBP of at least 120/70 mm Hg in the JNC7 analysis and as mean asleep SBP/DBP of at least 110/65 mm Hg in the 2017 ACC-AHA guideline analysis. Masked asleep hypertension was defined as high asleep BP without high clinic BP. Isolated masked asleep hypertension was defined as high asleep BP without high clinic BP or high awake BP. Persistent high BP was defined as high asleep BP with high clinic BP.
Statistical Analysis
Data were analyzed from March 4, 2019, to June 29, 2020. We used a 2-stage multiple imputation process to estimate the prevalence of asleep hypertension in US adults (eMethods in the Supplement). To validate our imputation approach, we performed 2 separate bootstrap cross-validations (eMethods in the Supplement). All analyses were performed using R, version 3.5.1 (R Project for Statistical Computing).
Results
In the pooled cohort of 3000 participants with ABPM data, the mean (SD) age was 52.0 (12.0) years; 1122 (37.4%) were men and 1878 (62.6%) were women; 900 (30.0%) were non-Hispanic White (Table 1). Participant characteristics for each of the 4 studies in the pooled cohort are shown in eTable 1 in the Supplement. Among the 17 969 participants in the NHANES cohort, mean (SD) age was 46.7 (17.5) years; 48.2% were men and 51.8% were women (weighted); and 64.9% were non-Hispanic White. Compared with the pooled cohort participants, NHANES participants were younger and more likely to be male and non-Hispanic White (Table 1).
Table 1. Characteristics of Study Participantsa.
Characteristic | Pooled cohort (n = 3000)b | NHANES (n = 17 969) |
---|---|---|
Demographic | ||
Age, mean (SD), y | 52.0 (12.0) | 46.7 (17.5) |
Age, y | ||
18-44 | 723 (24.1) | 47.0 |
45-64 | 1911 (63.7) | 34.7 |
≥65 | 366 (12.2) | 18.3 |
Male | 1122 (37.4) | 48.2 |
Race/ethnicity | ||
Non-Hispanic White | 900 (30.0) | 64.9 |
Non-Hispanic Black | 1641 (54.7) | 11.6 |
Hispanic | 348 (11.6) | 15.0 |
Other | 111 (3.7) | 8.5 |
High school degree | 2658 (88.6) | 84.5 |
Clinical | ||
Smoking status | ||
Never | 1962 (65.4) | 56.8 |
Former | 678 (22.6) | 23.9 |
Current | 315 (10.5) | 19.2 |
BMI, mean (SD) | 29.8 (6.4) | 29.0 (6.9) |
Obesity (BMI ≥30) | 1245 (41.5) | 37.1 |
Chronic kidney disease | 297 (9.9) | 14.6 |
Diabetes | 471 (15.7) | 12.6 |
History of cardiovascular disease | 165 (5.5) | 8.7 |
Blood pressure | ||
Antihypertensive use | 945 (31.5) | 23.3 |
Clinic BP, mean (SD), mm Hg | ||
Systolic | 121.4 (16.1) | 122.1 (17.1) |
Diastolic | 74.9 (9.5) | 70.5 (11.2) |
Awake ambulatory BP, mean (SD), mm Hg | ||
Systolic | 127.2 (13.5) | NA |
Diastolic | 78.5 (8.8) | NA |
Asleep ambulatory BP, mean (SD), mm Hg | ||
Systolic | 113.5 (15.3) | NA |
Diastolic | 65.8 (9.4) | NA |
Masked asleep hypertension | ||
JNC7 | 837 (27.9) | NA |
2017 ACC-AHA | 888 (29.6) | NA |
Abbreviations: ACC-AHA, American College of Cardiology–American Heart Association; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); BP, blood pressure; JNC7, Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; NHANES, National Health and Nutrition Examination Survey.
Unless otherwise indicated, data are expressed as number (percentage) of patients for the pooled cohort and weighted percentages for the NHANES cohort.
Forty-one participants were missing information on BMI; 31, educational level; 46, smoking status; and 11, clinic BP or use of antihypertensives.
The estimated prevalence of masked asleep hypertension among US adults was 18.8% (95% CI, 16.7%-20.8%) using the JNC7 BP thresholds and 22.7% (95% CI, 20.6%-24.8%) using the 2017 ACC-AHA BP thresholds (Table 2 and Figure). This corresponds to an estimated 44.4 (95% CI, 39.1-49.7) million and 53.7 (95% CI, 47.9-59.6) million US adults with masked asleep hypertension using the respective guidelines. The prevalence of masked asleep hypertension was higher among older adults (aged ≥65 years, 24.4% [95% CI, 20.7%-28.0%]), men (27.0% [95% CI, 24.1%-29.9%]), non-Hispanic Black individuals (28.7% [95% CI, 25.4%-32.0%]), those who were taking antihypertensives (24.4% [95% CI, 21.1%-27.8%]), those who had masked daytime hypertension (44.7% [95% CI, 40.1%-49.3%]), and those with diabetes (27.6% [95% CI, 23.5%-31.8%]), obesity (24.3% [95% CI, 21.8%-26.9%]), or chronic kidney disease (21.5% [95% CI, 17.3%-25.6%]) using the 2017 ACC-AHA guideline. In addition, we estimated that 11.9% (28.2 million) of US adults had isolated masked asleep hypertension according to JNC7 guidelines, and 13.3% (31.5 million) had it according to 2017 ACC-AHA BP guideline criteria.
Table 2. Estimated Prevalence and Number of US Adults With Masked Asleep Hypertension.
Variable | JNC7 definition | 2017 ACC-AHA definition | ||
---|---|---|---|---|
Prevalence, % (95% CI) | No. of US adults (95% CI), million | Prevalence, % (95% CI) | No. of US adults (95% CI), million | |
Overall | 18.8 (16.7-20.8) | 44.4 (39.1-49.7) | 22.7 (20.6-24.8) | 53.7 (47.9-59.6) |
Antihypertensive use | ||||
No | 16.4 (14.1-18.7) | 29.8 (25.3-34.4) | 22.2 (19.6-24.7) | 40.2 (35.0-45.5) |
Yes | 26.5 (22.5-30.4) | 14.6 (12.2-17.0) | 24.4 (21.1-27.8) | 13.5 (11.3-15.6) |
Masked daytime hypertension | ||||
No | 14.7 (12.8-16.6) | 28.2 (24.1-32.3) | 16.8 (14.8-18.8) | 31.5 (27.1-35.8) |
Yes | 36.7 (32.2-41.2) | 16.2 (13.4-19.0) | 44.7 (40.1-49.3) | 22.3 (18.9-25.7) |
Sex | ||||
Male | 23.7 (20.5-26.9) | 27.1 (23.1-31.0) | 27.0 (24.1-29.9) | 30.8 (27.0-34.6) |
Female | 14.2 (12.2-16.2) | 17.4 (14.8-19.9) | 18.7 (16.2-21.2) | 22.9 (19.7-26.2) |
Age, y | ||||
18-44 | 12.4 (9.5-15.2) | 13.8 (10.5-17.0) | 20.0 (16.5-23.5) | 22.2 (18.2-26.3) |
45-64 | 23.0 (20.2-25.8) | 18.9 (16.3-21.5) | 25.5 (22.8-28.2) | 20.9 (18.2-23.6) |
≥65 | 27.2 (23.0-31.4) | 11.8 (9.7-13.9) | 24.4 (20.7-28.0) | 10.6 (8.7-12.5) |
Race/ethnicity | ||||
Non-Hispanic White | 17.2 (14.6-19.8) | 26.4 (21.3-31.5) | 22.1 (19.5-24.7) | 34.0 (28.4-39.5) |
Non-Hispanic Black | 28.8 (25.2-32.3) | 7.9 (6.3-9.4) | 28.7 (25.4-32.0) | 7.9 (6.4-9.4) |
Hispanic | 18.2 (14.8-21.6) | 6.5 (4.9-8.1) | 21.9 (18.4-25.4) | 7.8 (6.0-9.6) |
Other | 18.2 (11.4-25.0) | 3.7 (2.2-5.1) | 20.4 (14.1-26.7) | 4.1 (2.7-5.5) |
Diabetes | ||||
No | 16.8 (14.7-18.9) | 34.8 (29.9-39.6) | 22.0 (19.6-24.3) | 45.5 (40.0-51.0) |
Yes | 32.4 (27.5-37.3) | 9.7 (8.1-11.3) | 27.6 (23.5-31.8) | 8.2 (6.9-9.6) |
Obesity | ||||
No | 17.0 (14.6-19.3) | 25.2 (21.4-29.0) | 21.7 (19.1-24.3) | 32.3 (27.9-36.6) |
Yes | 21.8 (19.0-24.7) | 19.2 (16.5-21.9) | 24.3 (21.8-26.9) | 21.4 (18.8-24.1) |
Chronic kidney disease | ||||
No | 17.2 (15.1-19.3) | 34.8 (30.2-39.3) | 22.9 (20.6-25.2) | 46.3 (41.0-51.6) |
Yes | 27.9 (22.9-33.0) | 9.7 (7.7-11.6) | 21.5 (17.3-25.6) | 7.4 (5.9-9.0) |
Abbreviations: ACC-AHA, American College of Cardiology–American Heart Association; JNC7, Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.
In the 2 validation analyses, the mean difference between the imputed and observed prevalence of masked asleep hypertension ranged from −0.8% (95% CI, −6.8% to 5.3%) to 0.9% (95% CI, −4.3% to 6.1%) (eTable 2 in the Supplement). In addition, the estimated prevalence of persistent high BP among US adults was 10.6% (95% CI, 9.7%-11.6%; 25.2 [95% CI, 22.6-27.7] million US adults) and 25.6% (95% CI, 24.2%-27.0%; 60.5 [95% CI, 55.5-65.6] million US adults) using the JNC7 and 2017 ACC-AHA BP guideline thresholds, respectively (eTable 3 in the Supplement).
Discussion
In this study, we estimated that the prevalence of masked asleep hypertension was 18.8% (44.4 million US adults) using the JNC7 guideline BP thresholds and 22.7% (53.7 million US adults) using the 2017 ACC-AHA guideline BP thresholds. We also estimated that 11.9% (28.2 million) and 13.3% (31.5 million) of US adults had isolated masked asleep hypertension according to JNC7 and 2017 ACC-AHA criteria, respectively. These results underscore the potential importance of using ABPM not only to confirm a diagnosis of hypertension but to identify other high-risk BP phenotypes.
Ambulatory BP measurement allows clinicians to determine an individual’s BP phenotype and provide better estimates of cardiovascular disease risk than clinic BP alone.1 Both high 24-hour and asleep BPs are associated with an increased risk for all-cause mortality and cardiovascular disease events, even after adjusting for clinic BP.2,3 Regardless of the BP thresholds used to define it, the high prevalence of masked asleep hypertension suggests it may account for a substantial proportion of cardiovascular disease risk in the United States. Although the US Preventive Services Task Force guideline, 2017 ACC-AHA BP guideline, and other international guidelines recommend using ABPM to diagnose hypertension, screening for asleep hypertension is not currently recommended by the US guidelines.1,13,14 Evidence regarding the use of antihypertensives to reduce cardiovascular disease events in asleep hypertension is also lacking.
Limitations
Several limitations of our study should be considered. We assume the association between asleep hypertension and the variables that were present in the smaller pooled cohort was generalizable to the larger NHANES population. The total sample size of participants with 24-hour ABPM data was relatively small to allow reliable estimation of prevalence in some subgroups of interest. Although we included a racially and geographically diverse population, ABPM has yet to be collected in nationally representative US samples.
Conclusions
We estimated that the prevalence of masked asleep hypertension among US adults was 18.8% (44.4 million) using the JNC7 BP thresholds and 22.7% (53.7 million) using the 2017 ACC-AHA BP thresholds. The estimated prevalence of isolated masked asleep hypertension was 11.9% (28.2 million US adults) and 13.3% (31.5 million US adults) using JNC7 and 2017 ACC-AHA criteria, respectively. Future research should investigate the possible cardiovascular risk reduction and economic benefits of treating asleep hypertension.
References
- 1.Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2018;138(17):e484-e594. doi: 10.1161/HYP.0000000000000066 [DOI] [PubMed] [Google Scholar]
- 2.Yano Y, Tanner RM, Sakhuja S, et al. Association of daytime and nighttime blood pressure with cardiovascular disease events among African American individuals. JAMA Cardiol. 2019;4(9):910-917. doi: 10.1001/jamacardio.2019.2845 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Yang WY, Melgarejo JD, Thijs L, et al. ; International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes (IDACO) Investigators . Association of office and ambulatory blood pressure with mortality and cardiovascular outcomes. JAMA. 2019;322(5):409-420. doi: 10.1001/jama.2019.9811 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Hansen TW, Li Y, Boggia J, Thijs L, Richart T, Staessen JA. Predictive role of the nighttime blood pressure. Hypertension. 2011;57(1):3-10. doi: 10.1161/HYPERTENSIONAHA.109.133900 [DOI] [PubMed] [Google Scholar]
- 5.Wang YC, Shimbo D, Muntner P, Moran AE, Krakoff LR, Schwartz JE. Prevalence of masked hypertension among US adults with nonelevated clinic blood pressure. Am J Epidemiol. 2017;185(3):194-202. doi: 10.1093/aje/kww237 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Chobanian AV, Bakris GL, Black HR, et al. ; Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National Heart, Lung, and Blood Institute; National High Blood Pressure Education Program Coordinating Committee . Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension. 2003;42(6):1206-1252. doi: 10.1161/01.HYP.0000107251.49515.c2 [DOI] [PubMed] [Google Scholar]
- 7.Friedman GD, Cutter GR, Donahue RP, et al. CARDIA: study design, recruitment, and some characteristics of the examined subjects. J Clin Epidemiol. 1988;41(11):1105-1116. doi: 10.1016/0895-4356(88)90080-7 [DOI] [PubMed] [Google Scholar]
- 8.Sempos CT, Bild DE, Manolio TA. Overview of the Jackson Heart Study: a study of cardiovascular diseases in African American men and women. Am J Med Sci. 1999;317(3):142-146. doi: 10.1016/S0002-9629(15)40495-1 [DOI] [PubMed] [Google Scholar]
- 9.Shimbo D, Newman JD, Schwartz JE. Masked hypertension and prehypertension: diagnostic overlap and interrelationships with left ventricular mass: the Masked Hypertension Study. Am J Hypertens. 2012;25(6):664-671. doi: 10.1038/ajh.2012.15 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Abdalla M, Goldsmith J, Muntner P, et al. Is isolated nocturnal hypertension a reproducible phenotype? Am J Hypertens. 2016;29(1):33-38. doi: 10.1093/ajh/hpv058 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Thijs L, Hansen TW, Kikuya M, et al. ; IDACO Investigators . The International Database of Ambulatory Blood Pressure in relation to Cardiovascular Outcome (IDACO): protocol and research perspectives. Blood Press Monit. 2007;12(4):255-262. doi: 10.1097/MBP.0b013e3280f813bc [DOI] [PubMed] [Google Scholar]
- 12.Pickering TG, Hall JE, Appel LJ, et al. Recommendations for blood pressure measurement in humans and experimental animals: part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Circulation. 2005;111(5):697-716. doi: 10.1161/01.CIR.0000154900.76284.F6 [DOI] [PubMed] [Google Scholar]
- 13.Williams B, Mancia G, Spiering W, et al. ; ESC Scientific Document Group . 2018 ESC/ESH Guidelines for the management of arterial hypertension. Eur Heart J. 2018;39(33):3021-3104. doi: 10.1093/eurheartj/ehy339 [DOI] [PubMed] [Google Scholar]
- 14.Siu AL; US Preventive Services Task Force . Screening for high blood pressure in adults: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2015;163(10):778-786. doi: 10.7326/M15-2223 [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.