Home Blood Pressure Monitoring in Women of Child-Bearing Age With Hypertension From 2009 to 2014

Abstract

BACKGROUND

Hypertension (HTN) is a leading cause of maternal mortality, and HTN guidelines recommend home blood pressure monitoring (HBPM) to help achieve blood pressure (BP) control. Evidence suggests that HBPM be coupled with a care team to maximize its effectiveness. HBPM use and the prevalence of provider counseling in child-bearing age women with HTN are unknown.

METHODS

We used data from 3,614 women in the cross-sectional National Health and Nutrition Examination Surveys 2009–2014 to determine HBPM use and provider counseling for women of child-bearing age (20–50 years) with and without HTN. HBPM use and provider counseling were self-reported. We examined rates of HBPM use by race/ethnicity, poverty–income ratio (PIR), education, and insurance.

RESULTS

Among women of child-bearing age with HTN, the mean (SE) age was 37.0 (0.3) years, the mean (SE) BMI was 35.5 (0.6) kg/m², and 73% were on BP medication. Of these women with HTN, 49.6% reported HBPM use in the past year and 40.4% received provider counseling. There was no significant difference in HBPM use by race/ethnicity, PIR, or insurance, though higher education was associated with HBPM use. Women with HTN who received provider counseling were more likely to use HBPM (odds ratio = 15.7, 95% confidence interval 9.1–26.9).

CONCLUSIONS

Nearly half of child-bearing age women with HTN have adopted HBPM, and provider counseling was strongly associated with HBPM use. This highlights a need and opportunity for providers to improve BP management by supporting a popular and valuable monitoring approach among women of child-bearing age with HTN.

Graphical Abstract

Graphical Abstract.

Hypertension (HTN), a leading cause of maternal morbidity and mortality, contributes to nearly 40% of maternal deaths.^1,2 One in 5 US women of child-bearing age has HTN.³ Since 1970, there has been a 13-fold increase in HTN during pregnancy as maternal age, obesity, and substance use have increased.^1,4 Given the effects of HTN in the peripartum period and its contribution to premature cardiovascular disease, improving blood pressure (BP) control is one of 3 top priorities of the Surgeon General’s 2020 Maternal Health Action Plan.⁵

The COVID pandemic has hastened the shift of outpatient care from all clinic-based care to include more remote monitoring. Regular BP measurement is the first and fundamental step to control BP, and home BP monitoring (HBPM) coupled with care team involvement maximizes its effectiveness.³ HBPM is especially important in child-bearing age women, given the frequent changes in antihypertensive therapies before, during, and after pregnancy, high rates of white-coat HTN, and BP fluctuations associated with pregnancy.⁶ With hypertensive disorders causing more severe maternal morbidity in pregnant and postpartum women of color, HBPM is one intervention proven to reduce health inequities in peripartum care.⁷

While HBPM to confirm the diagnosis and achieve control of HTN is currently recommended,^6,8,9 patterns of HBPM and provider counseling in women of child-bearing age with HTN in the United States are unknown. Using National Health and Nutrition Examination Surveys (NHANES) data, we assessed the frequency of HBPM and provider counseling for HBPM among women of child-bearing age with HTN.

METHODS

The NHANES are cross-sectional surveys examining the health of the noninstitutionalized US population, with participants recruited from US communities using a complex, multistage sampling design that is representative of the US population.¹⁰ All procedures were approved by the National Center for Health Statistics (NCHS) Research Ethics Review Board, and all participants provided written informed consent.¹⁰ The data underlying this article are publicly available through NHANES at www.cdc.gov/nchs/nhanes/index.htm.We used 3 consecutive NHANES surveys (2009–2010, 2011–2012, 2013–2014) to study pregnant women and women of child-bearing age (20–50 years of age), as these years included questions to adult participants about HBPM. Women <20 years were excluded since they were not asked about pregnancy status and rates of HTN were low. Initially, we aimed to include pregnant women with HTN as a separate category (N = 9), but these data were not reported separately due to the sample size. Women were excluded if menopausal or posthysterectomy, missing demographic variables, or missing BP data. HTN was defined as self-report of a provider diagnosis, requiring an affirmative response to, “Have you ever been told by a doctor/other health professional that you had hypertension, also called high blood pressure?” Women without an affirmative response were included in the “without self-reported HTN” group.

Demographic variables included education, income based on poverty–income ratio (PIR, <1.85 vs. ≥1.85), and insurance type (private, low-income, or other). Race/ethnicity, which was based on self-reported information, was classified as Hispanic (which included Mexican American or Other Hispanic), Non-Hispanic White, and Non-Hispanic Black. Participants not self-reporting one of the above categories were included as “Other.”

HBPM use was defined as a participant answering “yes” to the question, “Did you take your blood pressure at home during the last 12-months?” Those indicating yes were then asked, “How often did you check your blood pressure at home during the last 12 months?” HBPM frequency in the past year was categorized as monthly (12–51 times) and weekly (52 or more times). All participants were also asked about HBPM provider counseling, defined by an affirmative response to “Did a doctor or other health professional tell you to take your blood pressure at home?” We determined the weighted prevalence of HBPM use and HBPM provider counseling using the sample weights, primary sampling units, and strata recommended to account for the NHANES complex sampling design.¹⁰ Standard errors were determined using the Taylor series (linearization) method. We examined rates of HBPM use by race/ethnicity, PIR, education, and insurance type. We used logistic regression models, adjusted for age, BMI, BP, education, PIR, insurance type, and comorbidities, to determine if provider counseling for HBPM was associated with HBPM use among women of child-bearing age with HTN.

RESULTS

Among women of child-bearing age with HTN, mean (SE) age was 37.0 (0.3) years and 30.8% were Black (Table 1). The mean BP of those on BP medications was 124.9 ± 1.1/77.2 ± 0.9 vs. 130.7 ± 2.5/77.9 ± 1.7 mm Hg for women not on BP medications. Nearly half (49.6%) reported HBPM in the past year, and 22.9% used HBPM at least weekly. Of all women of child-bearing age with HTN, 42.6% of these women used HBPM monthly or more frequently. In this same population, 40.4% received HBPM provider counseling, and of these, 85.7% followed the recommendation and engaged in HBPM. In logistic regression modeling, provider counseling for HBPM was highly associated with any HBPM use in women of child-bearing age with HTN (odds ratio 15.7, 95% confidence interval 9.1–26.9). Achieving at least some college education was also positively associated with any HBPM use (odds ratio 1.43, 95% confidence interval 1.03–2.0). There was no significant difference in HBPM use by race/ethnicity groups, PIR ratio (<1.85 vs. ≥1.85), or type of insurance.

Table 1.

Population characteristics and HBPM use in women of child-bearing age by hypertension status^a

	All women of child-bearing age (N = 2,872)	Women with self-reported HTN (N = 250)	Women without self-reported HTN (N = 2,622)
US populationb	39,975,273	4,950,863	36,980,981
Age (y)	31.7(0.3)	37.0 (0.3)	31.3 (0.3)
Race/ethnicity
Hispanic	17.5%	14.5%	17.8%
Non-Hispanic White	59.8%	49.4%	60.7%
Non-Hispanic Black	13.4%	30.8%	12.0%
Other	9.2%	5.3%	9.5%
Education level
High school	29.5%	36.8%	28.8%
≥Some college	70.5%	63.2%	71.2%
Poverty–income ratio
≤1.85	32.1%	48.3%	41.6%
>1.85	57.9%	51.7%	58.4%
Smoking
Never	67.3%	55.9%	68.3%
Former	12.3%	18.1%	11.8%
Current	20.4%	26.0%	19.9%
Diabetes	2.8%	16.1%	1.6%
Obesity (BMI ≥30)	33.3%	71.8%	30.0%
BMI (kg/m2)	28.2 (0.2)	35.5 (0.6)	27.6 (0.2)
Cardiovascular diseasec	1.2%	7.4%	0.7%
Systolic BP (mm Hg)	111.1 (0.4)	126.4 (1.2)	109.9 (0.3)
Diastolic BP (mm Hg)	68.3 (0.4)	77.4 (0.9)	67.6 (0.3)
Currently on BP medication	5.6%	73.2%	0%
HBPM provider counselingd	4.9%	40.4%	1.9%
HBPM usee	12.2%	49.6%	9.1%
Monthly HBPMf	3.4%	19.7%	2.2%
Weekly HBPMf	3.6%	22.9%	1.8%

Abbreviations: BMI, body mass index; BP, blood pressure; HBPM, home blood pressure monitoring; HTN, hypertension; NHANES, National Health and Nutrition Examination Surveys.

^aData are reported as mean percentage of subjects or mean (SE) number of indicated units and weighted based on the complex NHANES sampling strategy, from NHANES surveys 2009–2014.

^bBased on the complex sampling design of NHANES to estimate prevalence in the US population.

^cCardiovascular disease defined as a diagnosis of coronary artery disease, congestive heart failure, or stroke.

^dParticipants self-report of healthcare provider counseling to use HBPM.

^eHBPM use defined as measuring BP at home in the last 12 months.

^fHBPM frequency: 12–51 times in the past 12 months was categorized as monthly; 52 or more times in the past 12 months was categorized as weekly.

DISCUSSION

This study was undertaken to evaluate patterns of HBPM and provider counseling in women of child-bearing age with HTN in the United States. Unfortunately, there were too few pregnant women with HTN to provide reliable estimates. Using NHANES data, we found that nearly half of all women of child-bearing age with HTN were using HBPM, with the majority of these women monitoring at least monthly. Women of child-bearing age with HTN reported provider counseling on HBPM at nearly the level of adoption, and provider counseling was highly associated with HBPM use. These findings highlight the importance of providers’ counseling to reinforce HBPM.

Both diagnosis and effective management of HTN require accurate BP measurements.^3,11 HBPM overcomes many limitations of office BP measurement, such as differentiating white-coat HTN from HTN and encouraging patient engagement with self-care. When using an automated and validated home monitor, these home BP measures can be both a practical and effective way to monitor HTN status. HBPM measurements are also better than clinic BP measurements at predicting cardiovascular risk.¹² However, education on the proper technique for HBPM, ideally from healthcare providers, is important to allow for accurate BP assessment.¹² This includes guidance on validated devices, appropriate cuff size, and instructions on the procedure of taking multiple readings in an appropriate position to prevent erroneous measurements.^3,9 While clinic-based BP is standard in medical practice, HBPM can aid in more timely diagnosis and management of HTN, while also distinguishing between white-coat HTN and sustained HTN.^3,9,12 In the United States, adults with diagnosed, treated, and controlled HTN were all more likely to use HBPM than those with undiagnosed, untreated, and uncontrolled HTN, respectively.¹³ When used for postpartum HTN management, HBPM reduced racial inequities in obtaining BP, decreased admissions, and improved postpartum BP management.⁷ Additionally, increasing internet and smartphone adoption by child-bearing age women along with validated BP monitors equipped for remote data transmission has made HBPM and healthcare team feedback increasingly popular and accessible.^14–16

HBPM use is increasing in the US adults, with 36.6% of those with HTN using HBPM at least monthly.¹⁷ Our findings suggest that women of child-bearing age with HTN have similar engagement with HBPM use to the general population with HTN, and provider counseling was strongly associated with HBPM.¹⁷ Prior studies have demonstrated that provider counseling was associated with an increase in HBPM use (approximately 8-fold) in the general US population.¹³ In adults with HTN, higher education (some college or beyond) was also associated with HBPM use.¹³ While the relationship between education, health literacy, and HBPM use requires a more in-depth evaluation, 1 cluster-randomized trial showed that adequate health literacy was associated with weekly HBPM at the end of the 6-month study.¹⁸

This study has several limitations. First, HTN was defined by self-report, which may result in misclassification of participants given changing clinical definitions over time. Second, the assigned frequency of HBPM may be inaccurate if participants recently started or changed frequency but report HBPM as weekly or monthly for the prior 12 months.

Our study provides a benchmark for counseling rates and participation in HBPM for child-bearing age women with HTN. Unfortunately, a standardized approach in ambulatory clinics for HBPM education is not widely adopted, representing a missed opportunity and critical gap in care.¹² This study also highlights the need for data on HBPM and provider counseling in pregnant women with HTN, as increasing maternal age, obesity, substance abuse, and fertility treatments all contribute to higher rates of HTN in pregnancy in the US population.^4,19 These findings should mobilize obstetric, primary care, and cardiology providers to counsel all child-bearing age women with HTN, especially those with plans for pregnancy, on HBPM to improve BP control and to establish the patient’s expertise prior to pregnancy.

HBPM counseling by healthcare providers for child-bearing age women with HTN is important in the United States, as provider counseling improves engagement of this population in HBPM. The lack of data for HBPM in pregnancy is concerning and highlights a need and opportunity to study this important approach in pregnant women with HTN.

FUNDING

Dr Kovell is supported in part by a Physician Development Pilot Grant at the University of Chan Medical School. Dr Juraschek is supported by NIH/NHLBI K23HL135273.

DISCLOSURE

Dr McManus reports grants and personal fees from Bristol Myers Squibb and Pfizer, grants from Boehringer Ingelheim, nonfinancial support from Apple, personal fees and nonfinancial support from Samsung, Flexcon, personal fees from Avania, grants and personal fees from Heart Rhythm Society, and personal fees and nonfinancial support from Fitbit, outside the submitted work. The remaining authors have no conflicts of interests to disclose.