Abstract
Background
The mean systolic blood pressure (SBP) for US adults increases with age. Determining characteristics of US adults ≥65 years with normal blood pressure (BP) may inform approaches to prevent this increase.
Methods
We analyzed US National Health and Nutrition Examination Survey 2011–2018 data (n = 21,581). BP was measured up to 3 times and averaged. Normal BP was defined as SBP <120 mm Hg and diastolic BP (DBP) <80 mm Hg among participants not taking antihypertensive medication. Those with SBP ≥120 mm Hg, DBP ≥80 mm Hg, self-reporting having hypertension or taking antihypertensive medication were categorized as having elevated BP or hypertension.
Results
The prevalence of normal BP was 57.8%, 25.3%, 11.2%, and 5.0% among US adults who were 18–44, 45–64, 65–74, and ≥75 years, respectively. After multivariable adjustment, in US adults ≥65 years of age, normal BP vs. elevated BP/hypertension was more common among those with moderate and no vs. heavy alcohol consumption (prevalence ratio [PR] 3.03; 95% confidence interval [CI] 1.25–7.36 and 2.53; 95% CI 0.96–6.65, respectively), ≥150 vs. <150 minutes of physical activity per week (PR = 1.44; 95% CI 1.01–2.05), overweight and normal weight vs. obesity (PR = 1.88; 95% CI 1.22–2.90 and 2.94; 95% CI 1.89–4.59, respectively), and a high Dietary Approaches to Stop Hypertension score (PR = 1.43; 95% CI 1.00–2.05). US adults ≥65 years with normal BP vs. elevated BP/hypertension were less likely to have good or fair/poor vs. excellent/very good self-rated health, diabetes, albuminuria, atherosclerotic cardiovascular disease, and heart failure.
Conclusions
Among US adults ≥65 years, normal BP was associated with healthy lifestyle factors and a lower prevalence of adverse health conditions.
Keywords: aging, blood pressure, cardiovascular risk, hypertension, lifestyle factors
The mean systolic blood pressure (SBP) for the US population increases with age.1 However, an increase in SBP with age may not occur for all US adults. During follow-up of the Coronary Artery Risk Development in Young Adults (CARDIA) study and the Jackson Heart Study (JHS), 2 US-based cohort studies, a subset of participants did not experience an increase in blood pressure (BP).1,2 However, at the most recent CARDIA study examination, the oldest participants were 60 years of age and the JHS had only 8 years of follow-up to evaluate changes in BP.
Over the last several decades, randomized trials have demonstrated the BP-lowering benefit of several lifestyle factors including limiting or eliminating alcohol consumption, increasing physical activity, normal body mass index (BMI), a heart-healthy diet, dietary sodium reduction, and potassium supplementation.3,4 These factors may facilitate the maintenance of normal BP across the life course for US adults. Additionally, maintaining normal BP may lower the risk for kidney disease and cardiovascular disease.2 Determining the characteristics of US adults ≥65 years old with normal BP may inform approaches to prevent the increase in mean SBP with age that currently occurs in the United States. The objectives of this study were to determine the age-specific proportion of US adults with normal BP, and to identify lifestyle factors and health conditions associated with having normal BP among US adults ≥65 years of age. For comparison, we estimated the association of lifestyle factors and health conditions with normal BP among US adults who were 18–44 and 45–64 years of age. To accomplish these objectives, data from the US National Health and Nutrition Examination Survey (NHANES) were analyzed.
METHODS
NHANES was conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention.5 Since 1999–2000, NHANES has been conducted in 2-year cycles. For each cycle, potential participants are identified through stratified, multistage probability sampling of the noninstitutionalized US population. Multiple NHANES cycles can be combined following the National Center for Health Statistics analytic guidelines to provide more stable statistical estimates.6 Four NHANES cycles, 2011–2012, 2013–2014, 2015–2016, and 2017–2018, were pooled for the current analyses. These analyses were restricted to 21,581 nonpregnant participants with BP measurements and information on antihypertensive medication use. The National Center for Health Statistics Institutional Review Board approved the NHANES protocols for each cycle and all participants provided written informed consent.
NHANES data collection occurred during an in-home interview, a study visit at a mobile examination center and a postexamination telephone interview. Age, sex, race–ethnicity, current cigarette smoking, alcohol consumption, physical activity, general self-rated health, a history of hypertension, diabetes, heart disease, myocardial infarction, stroke, and heart failure and glucose-lowering and antihypertensive medication use were assessed using questionnaires during the in-home interview. Alcohol consumption was categorized as none, moderate (>0–7 drinks per week for women and >0–14 drinks per week for men), or heavy (>7 drinks per week for women and >14 drinks per week for men). General self-rated health was reported in 5 categories and grouped as excellent/very good, good, and fair/poor. A history of atherosclerotic cardiovascular disease (ASCVD) was defined by coronary heart disease, myocardial infarction, or stroke. During the study visit, height and weight were measured, blood and urine samples were collected, and a medication inventory and 24-hour dietary recall was conducted. Using the height and weight measurements, BMI was calculated and categorized as normal (BMI <25 kg/m2), overweight (BMI of 25 to <30 kg/m2), or obese (BMI ≥30 kg/m2). Diabetes was defined by a self-report of a prior diagnosis with use of glucose-lowering medication or a glycated hemoglobin ≥6.5%. Estimated glomerular filtration rate (eGFR) was calculated using age, sex, race/ethnicity, serum creatinine, and the Chronic Kidney Disease Epidemiology equation.7 Reduced eGFR was defined by values <60 ml/min/1.73 m2. Albuminuria was defined as a urine albumin-to-creatinine ratio >30 mg/g. A second 24-hour dietary recall was conducted by telephone 3–10 days following the examination. For each dietary recall, daily intake of energy and nutrients were estimated using the US Department of Agriculture Food and Nutrient Database for Dietary Studies. The average intake of energy and nutrients were averaged using the 2 dietary recalls. A Dietary Approaches to Stop Hypertension (DASH) score was created from the intake of 9 nutrient targets including total fat, saturated fat, protein, fiber, cholesterol, potassium, magnesium, calcium, and sodium.8–10 This DASH score has a possible range from 0 to 9, where a higher score indicates a dietary pattern more consistent with the DASH diet.8 A DASH score ≥3.5, which represented the top 20% for US adults, was considered high. Overall, 21% of participants (n = 4,484) were missing diet data.
BP was measured up to 3 times by a trained physician following a standardized protocol. The mean of all available readings was used to estimate a participant’s BP. Taking antihypertensive medication was defined by participant self-report or the identification of antihypertensive drugs during the medication inventory. Among participants who reported not having ever been told by a doctor or other healthcare professional that they had hypertension or high BP and were not taking antihypertensive medication, normal BP was defined as SBP <120 mm Hg and diastolic BP (DBP) <80 mm Hg and elevated BP was defined as SBP of 120–129 mm Hg and DBP <80 mm Hg.3 Hypertension was defined as SBP ≥130 mm Hg, DBP ≥80 mm Hg, being told by a doctor or other healthcare professional they had hypertension or the use of antihypertensive medication. While some participants who reported being told they had hypertension may not have ever had it, this approach was chosen to avoid including those who may have previously had hypertension but whose BP decreased due to medical conditions such as heart failure in the normal BP group.11
Statistical analysis
We estimated the mean age-specific SBP and DBP using linear regression models for the overall US population and for women and men, separately. Age-specific SBP and DBP were estimated using the measured BP levels and after adjusting the measured levels for antihypertensive medication use as described by Law et al.12 Specifically, for each class of antihypertensive medication a participant was taking, we adjusted their SBP using the formula and we adjusted their DBP using the formula . Multinomial logistic regression was used to estimate the age-specific prevalence of normal BP, elevated BP, and hypertension for the overall population and for women and men, separately. Age was included in the linear and multinomial logistic regression models using linear and quadratic terms. We pooled together participants with elevated BP or hypertension for the remainder of the analyses. The prevalence of sociodemographic factors including age, sex, race/ethnicity, health behaviors including cigarette smoking, alcohol consumption, physical activity, BMI, and DASH score, and health outcomes including general self-rated health, diabetes, albuminuria, eGFR, history of ASCVD, and history of heart failure was estimated for US adults with normal BP and elevated BP/hypertension in 3 mutually exclusive age categories: 18–44, 45–64, and ≥65 years. We grouped US adults 65–74 and ≥75 years of age due to the small number (n = 88) of NHANES participants ≥75 years of age with normal BP. The adequacy of the sample size within each age group to produce reliable statistics was confirmed following guidance from the National Center for Health Statistics.13 Within each age group, the prevalence ratios (PRs) for normal BP vs. elevated BP/hypertension were calculated for demographic factors, health behaviors, general self-rated health, diabetes, reduced eGFR, albuminuria, history of ASCVD, and history of heart failure. PRs are measures of relative risk, similar to odds ratios or hazard ratios, which can be used in cross-sectional studies. They are calculated as the proportion of an exposed group that has an outcome divided by the proportion of an unexposed group that has the outcome (e.g., the proportion of women with normal BP divided by the proportion of men with normal BP). All models included sociodemographic factors and health behaviors. All calculations accounted for the NHANES stratified sampling approach and sampling weights were applied to obtain US nationally representative estimates.5
RESULTS
Mean SBP increased from 116 (95% confidence interval [CI] 116–116) mm Hg for US adults 18–44 years of age to 138 (95% CI 137–140) mm Hg for US adults ≥75 years of age while mean DBP was highest in US adults who were 45–64 years of age (Figure 1). Adjusting BP for antihypertensive medication use, mean SBP increased from 117 (95% CI 116–117) to 153 (95% CI 151–155) mm Hg for those age 18–44 years to those age ≥75 years. Mean SBP and DBP for women and men are provided in Supplementary Figures S1 and S2 online, respectively. The prevalence of normal BP was 57.8%, 25.3%, 11.2%, and 5.0% among US adults who were 18–44, 45–64, 65–74, and ≥75 years of age, respectively (Figure 2). Among US adults 18–44 and 45–64 years of age, the prevalence of normal BP was higher among women vs. men (Supplementary Figure S3 online). The prevalence of normal BP was 11.1% and 11.3% among women and men 65–74 years of age, respectively, and 5.0% and 5.1% among women and men, respectively, who were ≥75 years of age.
Figure 1.
Mean systolic and diastolic blood pressure from 18 to 80 years of age among US adults. The mean blood pressure for US adults 18–44, 45–64, 65–74, and ≥75 years of age is provided in the figure with 95% confidence intervals in parentheses. The left panel provides results from a model of the measured systolic and diastolic blood pressure. The right panel provides results from a model of systolic and diastolic blood pressure adjusted for antihypertensive medication use as described in the methods section.
Figure 2.
Prevalence of normal blood pressure, elevated blood pressure, and hypertension from 18 to 80 years of age among US adults. US adults >80 years of age are grouped as being 80 years old. Text in the figure indicates the percentage of US adults with each blood pressure level in the corresponding age group (e.g., 18–44 years), while shaded regions indicate the percentage of US adults with normal blood pressure at all values of age from 18 to 80 years.
Among US adults ≥65 years of age, those with normal BP vs. elevated BP/hypertension were less likely to be non-Hispanic Black adults (2.7% vs. 8.8%), and more likely to be non-Hispanic White adults (86.4% vs. 76.8%) (Table 1). Also, those with normal BP vs. elevated BP/hypertension were more likely to consume a moderate amount of alcohol (62.7% vs. 49.3%), participate in ≥150 minutes of moderate or vigorous physical activity per week (65.0% vs. 47.6%), and have a normal BMI (39.6% vs. 24.0%). A lower proportion of those ≥65 years of age with normal BP vs. elevated BP/hypertension reported fair/poor health (11.6% vs. 23.2%) and had diabetes (7.0% vs. 24.5%), albuminuria (6.6% vs. 20.9%), a history of ASCVD (10.2% vs. 23.1%), or heart failure (2.2% vs. 8.7%).
Table 1.
Characteristics of US adults with normal blood pressure and elevated blood pressure or hypertension by age grouping
| Age group | ||||||
|---|---|---|---|---|---|---|
| 18–44 years | 45–64 years | ≥65 years | ||||
| Elevated BP/hypertension (n = 3,962) 42.2% (40.5%–43.9%)a |
Normal BP (n = 5,549) 57.8% (56.1%–59.5%)a |
Elevated BP/hypertension (n = 5,624) 74.7% (72.8%–76.5%) |
Normal BP (n = 1,565) 25.3% (23.6%–27.2%) |
Elevated BP/hypertension (n = 4,572) 91.3% (89.7%–92.7%) |
Normal BP (n = 309) 8.7% (7.4%–10.3%) |
|
| Age, years | 32.7 (32.3–33.1) |
29.6 (29.1–30.0) |
55.0 (54.7–55.3) |
52.5 (52.0–52.9) |
73.1 (72.8–73.4) |
70.6 (69.9–71.3) |
| Women, % | 34.6% (32.8%–36.6%) |
58.9% (57.4%–60.5%) |
49.4% (47.6%–51.1%) |
57.9% (54.7%–61.1%) |
55.5% (53.8%–57.2%) |
54.1% (44.4%–63.5%) |
| Race–ethnicity, % | ||||||
| Non-Hispanic White | 56.2% (51.8%–60.7%) |
56.4% (52.3%–60.5%) |
67.0% (62.9%–70.9%) |
72.9% (68.7%–76.8%) |
76.8% (73.6%–79.8%) |
86.4% (81.9%–90.0%) |
| Non-Hispanic Black | 15.2% (12.3%–18.3%) |
11.2% (9.3%–13.3%) |
12.9% (10.8%–15.4%) |
5.9% (4.6%–7.4%) |
8.8% (7.0%–10.8%) |
2.7% (1.2%–5.5%) |
| Non-Hispanic Asian | 4.9% (4.0%–5.9%) |
7.3% (6.1%–8.7%) |
4.7% (3.9%–5.7%) |
5.7% (4.4%–7.3%) |
4.2% (3.3%–5.4%) |
3.2% (1.5%–5.9%) |
| Hispanic | 19.1% (16.3%–22.2%) |
21.3% (18.1%–24.8%) |
12.2% (10.0%–14.6%) |
12.5% (9.9%–15.4%) |
7.5% (5.8%–9.7%) |
7.0% (4.3%–10.5%) |
| Current smoking, % | 24.7% (22.7%–26.7%) |
19.6% (17.6%–21.6%) |
21.4% (19.8%–23.2%) |
16.1% (13.4%–19.1%) |
8.2% (7.0%–9.5%) |
14.2% (8.6%–21.6%) |
| Alcohol consumption, % | ||||||
| Heavy | 10.0% (8.6%–11.6%) |
6.4% (5.3%–7.7%) |
10.9% (9.5%–12.4%) |
6.5% (4.9%–8.4%) |
4.7% (3.7%–6.0%) |
2.2% (0.7%–5.5%) |
| Moderate | 68.9% (66.3%–71.3%) |
68.1% (65.3%–70.8%) |
57.7% (55.4%–60.0%) |
66.9% (63.0%–70.6%) |
49.3% (47.0%–51.6%) |
62.7% (54.3%–70.6%) |
| None | 21.1% (19.1%–23.3%) |
25.5% (22.7%–28.4%) |
31.4% (29.3%–33.5%) |
26.7% (23.2%–30.3%) |
46.0% (43.4%–48.6%) |
35.1% (27.3%–43.6%) |
| ≥150 min of physical activity per week, % | 74.7% (73.2%–76.2%) |
75.1% (73.4%–76.7%) |
59.7% (57.5%–61.9%) |
69.2% (65.6%–72.7%) |
47.6% (45.1%–50.1%) |
65.0% (56.6%–72.7%) |
| BMI, kg/m2 | 31.3 (30.9–31.7) |
26.8 (26.5–27.1) |
30.9 (30.6–31.3) |
27.0 (26.5–27.4) |
29.1 (28.9–29.4) |
26.8 (25.8–27.7) |
| BMI category, % | ||||||
| Obesity (≥30 kg/m2) | 50.5% (48.1%–53.0%) |
24.9% (23.0%–27.0%) |
48.5% (46.0%–51.0%) |
23.7% (20.3%–27.5%) |
39.5% (37.2%–41.7%) |
21.0% (14.7%–28.5%) |
| Overweight (25–29 kg/m2) | 27.7% (25.8%–29.8%) |
29.4% (27.9%–31.0%) |
32.3% (30.0%–34.8%) |
37.5% (34.2%–41.0%) |
36.5% (34.6%–38.5%) |
39.4% (29.5%–50.0%) |
| Normal (<25 kg/m2) | 21.7% (19.7%–23.9%) |
45.6% (43.3%–48.0%) |
19.2% (17.7%–20.8%) |
38.7% (34.4%–43.2%) |
24.0% (22.4%–25.7%) |
39.6% (30.1%–49.7%) |
| High DASH score | 17.6% (15.4%–19.9%) |
18.6% (17.0%–20.2%) |
18.1% (16.4%–19.8%) |
24.6% (20.5%–29.1%) |
18.7% (16.7%–20.8%) |
27.3% (19.1%–36.9%) |
| General health, % | ||||||
| Excellent/very good | 39.9% (37.4%–42.3%) |
56.5% (54.0%–59.0%) |
39.4% (36.6%–42.2%) |
59.9% (55.8%–63.9%) |
40.6% (37.9%–43.3%) |
65.8% (59.4%–71.9%) |
| Good | 40.6% (37.9%–43.4%) |
33.1% (30.9%–35.4%) |
37.1% (35.4%–38.9%) |
27.7% (24.6%–31.0%) |
36.3% (34.4%–38.2%) |
22.5% (17.3%–28.4%) |
| Fair/poor | 19.5% (17.6%–21.6%) |
10.4% (9.5%–11.4%) |
23.5% (21.5%–25.6%) |
12.4% (10.4%–14.6%) |
23.2% (21.1%–25.4%) |
11.6% (8.2%–15.8%) |
| Diabetes, % | 5.7% (4.9%–6.6%) |
1.3% (1.0%–1.8%) |
18.8% (17.3%–20.5%) |
4.2% (3.0%–5.7%) |
24.5% (22.3%–26.1%) |
7.0% (4.0%–11.1%) |
| Reduced eGFR, % | 0.8% (0.5%–1.2%) |
0.1% (0.0%–0.3%) |
5.1% (4.1%–6.2%) |
2.5% (1.4%–4.2%) |
26.8% (24.8%–28.8%) |
15.0% (10.1%–21.3%) |
| Albuminuria, % | 7.4% (6.5%–8.5%) |
5.3% (4.6%–6.1%) |
11.7% (10.6%–12.9%) |
3.9% (2.7%–5.4%) |
20.9% (19.0%–23.0%) |
6.6% (3.2%–11.9%) |
| History of ASCVD, % | 2.0% (1.6%–2.6%) |
0.5% (0.3%–0.7%) |
8.5% (7.4%–9.7%) |
1.8% (1.0%–2.8%) |
23.1% (21.6%–24.7%) |
10.2% (5.5%–16.9%) |
| History of heart failure, % | 1.0% (0.7%–1.5%) |
0.1% (0.0%–0.3%) |
2.5% (2.0%–3.1%) |
0.2% (0.1%–0.7%) |
8.7% (7.5%–10.0%) |
2.2% (0.6%–5.6%) |
| Systolic BP, mm Hg | 126 (126–127) |
108 (108–109) |
130 (129–131) |
109 (109–110) |
136 (135–137) |
111 (110–112) |
| Diastolic BP, mm Hg | 76 (76–77) |
66 (65–66) |
76 (76–77) |
68 (68–69) |
67 (67–68) |
63 (62–65) |
Numbers in table are mean or percentage with 95% confidence intervals provided in parentheses. Abbreviations: ASCVD, atherosclerotic cardiovascular disease; BMI, body mass index; BP, blood pressure; DASH, Dietary Approaches to Stop Hypertension; eGFR, estimated glomerular filtration rate. Moderate alcohol consumption included >0–7 drinks per week for women and >0–14 drinks per week for men. Heavy alcohol consumption included >7 drinks per week for women and >14 drinks per week for men. Physical activity included moderate or vigorous activities in work, leisure time, or commuting. The DASH score has a possible range of 0–9 with higher scores indicating consumption of dietary pattern with greater consistency with the DASH diet. A high DASH score was ≥3.5. Diabetes status included normal: HbA1c <5.7% without glucose-lowering medication, prediabetes: HbA1c between 5.7% and 6.4% without glucose-lowering medication, diabetes: HbA1c ≥6.5% or glucose-lowering medication use. Reduced estimated glomerular filtration rate was defined by <60 ml/min/1.73 m2. Albuminuria was defined by an albumin-to-creatinine ratio >30 mg/g.
aThe percentages in the header cells represent the age-stratified proportion of the population with elevated blood pressure/hypertension or normal blood pressure and are weighted to the US population. The number in the parentheses in the header cells represents the NHANES sample size included in this analysis.
Among US adults ≥65 years of age and after multivariable adjustment, normal BP was less common than elevated BP/hypertension at older age (PR 0.65; 95% CI 0.58–0.74 for each 5 years older age) and among non-Hispanic Black and Hispanic adults compared with non-Hispanic White adults (PRs 0.29; 95% CI 0.19–0.46 and 0.57 95% CI 0.40–0.80, respectively) (Table 2). Normal BP was more common among those with moderate and no vs. heavy alcohol consumption (PRs 3.03; 95% CI 1.25–7.36 and 2.53; 95% CI 0.96–6.65, respectively), who participated in ≥150 vs. <150 minutes of physical activity per week (PR 1.44; 95% CI 1.01–2.05), with overweight and normal weight vs. obesity (PR 1.88; 95% CI 1.22–2.90 and 2.94; 95% CI 1.89–4.59, respectively) and with vs. without a high DASH score (PR 1.43; 95% CI 1.00–2.05).
Table 2.
Demographic and lifestyle factors associated with having normal blood pressure vs. elevated blood pressure or hypertension among US adults by age group
| Prevalence ratio (95% confidence interval) for normal blood pressure | |||
|---|---|---|---|
| Age group | |||
| 18–44 years | 45–64 years | ≥65 | |
| Age, per 5 years | 0.92 (0.90–0.93) | 0.75 (0.71–0.80) | 0.65 (0.58–0.74) |
| Women vs. men | 1.51 (1.42–1.60) | 1.26 (1.14–1.39) | 1.05 (0.72–1.52) |
| Race–ethnicity | |||
| Non-Hispanic White | 1 (ref) | 1 (ref) | 1 (ref) |
| Non-Hispanic Black | 0.89 (0.83–0.95) | 0.55 (0.46–0.65) | 0.29 (0.19–0.46) |
| Non-Hispanic Asian | 1.10 (1.05–1.16) | 0.96 (0.84–1.10) | 0.85 (0.60–1.20) |
| Hispanic | 1.03 (0.96–1.09) | 0.76 (0.65–0.89) | 0.57 (0.40–0.80) |
| Current vs. former/never smoking | 0.97 (0.90–1.03) | 0.73 (0.65–0.89) | 1.56 (1.00–2.44) |
| Alcohol consumption | |||
| Heavy | 1 (ref) | 1 (ref) | 1 (ref) |
| Moderate | 1.18 (1.05–1.32) | 1.71 (1.34–2.17) | 3.03 (1.25–7.36) |
| None | 1.23 (1.08–1.41) | 1.56 (1.19–2.04) | 2.53 (0.96–6.65) |
| ≥150 vs. <150 min of physical activity per week | 1.01 (0.96–1.06) | 1.19 (1.02–1.38) | 1.44 (1.01–2.05) |
| BMI category | |||
| Obesity (≥30 kg/m2) | 1 (ref) | 1 (ref) | 1 (ref) |
| Overweight (25–29 kg/m2) | 1.50 (1.40–1.61) | 1.94 (1.64–2.30) | 1.88 (1.22–2.90) |
| Normal (<25 kg/m2) | 1.74 (1.64–1.86) | 2.74 (2.35–3.19) | 2.94 (1.89–4.59) |
| High DASH score | 1.01 (0.94–1.08) | 1.15 (0.97–1.35) | 1.43 (1.00–2.05) |
Numbers in table are prevalence ratio (95% confidence interval). Prevalence ratios were calculated in models that included age, sex, race–ethnicity, smoking, alcohol consumption, physical activity, body mass index, and high dietary approaches to top hypertension score. High dietary approaches to top hypertension score was ≥3.5. Abbreviations: BMI, body mass index; DASH, Dietary Approaches to Stop Hypertension.
Among US adults ≥65 years of age, the multivariable-adjusted PRs for normal BP vs. elevated BP/hypertension were 0.50 (95% CI 0.38–0.65) and 0.42 (95% CI 0.29–0.60) for good and fair/poor vs. excellent/very good self-rated health, respectively (Table 3). Additionally, the multivariable-adjusted PRs for normal BP vs. elevated BP/hypertension were 0.33 (95% CI 0.20–0.55) for diabetes, 0.74 (95% CI 0.48–1.12) for reduced eGFR, 0.41 (95% CI 0.22–0.78) for albuminuria, 0.48 (95% CI 0.27–0.86) for a history of ASCVD and 0.32 (95% CI 0.11–0.96) for a history of heart failure.
Table 3.
Association of self-rated health and medical conditions with normal blood pressure vs. elevated blood pressure or hypertension among US adults by age group
| Prevalence ratio (95% confidence interval) for normal blood pressure | |||
|---|---|---|---|
| Age group | |||
| 18–44 years | 45–64 years | ≥65 years | |
| General health | |||
| Excellent/very good | 1 (ref) | 1 (ref) | 1 (ref) |
| Good | 0.87 (0.82–0.92) | 0.73 (0.63–0.84) | 0.50 (0.38–0.65) |
| Fair/poor | 0.73 (0.67–0.79) | 0.57 (0.48–0.68) | 0.42 (0.29–0.60) |
| Diabetes | 0.55 (0.42–0.70) | 0.36 (0.26–0.49) | 0.33 (0.20–0.55) |
| Reduced eGFR | 0.33 (0.14–0.77) | 0.77 (0.47–1.25) | 0.74 (0.48–1.12) |
| Albuminuria | 0.80 (0.72–0.89) | 0.51 (0.39–0.68) | 0.41 (0.22–0.78) |
| History of ASCVD | 0.51 (0.34–0.75) | 0.37 (0.23–0.60) | 0.48 (0.27–0.86) |
| History of heart failure | 0.30 (0.14–0.65) | 0.20 (0.06–0.63) | 0.32 (0.11–0.96) |
Prevalence ratios calculated in models that included age, sex, race–ethnicity, smoking, alcohol consumption, physical activity, body mass index, high Dietary Approaches to Stop Hypertension score, and each variable listed in the table individually. Numbers in table are prevalence ratio (95% confidence interval). Abbreviations: ASCVD, atherosclerotic cardiovascular disease; eGFR, estimated glomerular filtration rate.
Discussion
Findings in the current study indicate that 11.2% and 5.0% of US adults aged 65–74 and ≥75 years of age have normal BP, respectively. Among US adults ≥65 years of age, having no or moderate alcohol consumption, participating in ≥150 minutes of physical activity per week, having overweight or normal weight vs. obesity and a high DASH score were associated with a higher prevalence of normal BP. In this age group, normal BP was associated with better self-rated health and a lower prevalence of several health conditions, including diabetes, albuminuria, a history of ASCVD, and heart failure.
In the current study, average SBP among US adults increased by 5–10 mm Hg per decade of age. Among Yanomamo and Xingu Indian tribes in South America and rural-dwelling adults in Papua New Guinea, the mean SBP and DBP were low and increased less than 1 mm Hg per 10 years older age.14 While these populations differ in many ways from individuals living in the United States, their data suggest the age-related rise in BP is not biologically determined.
Not being a heavy alcohol drinker, being physically active, and having overweight or a normal weight were associated with normal BP. These data are consistent with meta-analyses of randomized trials that have shown BP can be lowered through nonpharmacological interventions.15–18 The percentage of US adults with heavy alcohol consumption decreases with age. In contrast to the low proportion of US adults with heavy alcohol consumption, most US adults do not meet recommendations for physical activity and a high percentage of US adults are obese.19,20 A 2020 US Surgeon General Call-to-Action provided strategies to promote access to physical activity that can lower BP.21 The current study supports these interventions and suggests they can be used to maintain normal BP.
In the current study, a dietary pattern consistent with DASH was associated with a higher likelihood of having normal BP among US adults ≥65 years of age but not among younger adults. Prior studies have reported the BP-lowering benefit of dietary modification.8–10 However, dietary modification in isolation may not be sufficient to have normal BP. In the Diet, Exercise, and Weight Loss Intervention Trial (DEW-IT), the combination of the DASH diet, reduced sodium intake and weight loss reduced 24-hour SBP and DBP by 10 and 5 mm Hg, respectively, compared with usual care but there was no evidence that the DASH diet lowered SBP or DBP when added to a weight loss, physical activity, and alcohol reduction intervention in the PREMIER clinical trial.22,23 Data from DEW-IT and other studies indicate that a multifaceted approach of alcohol reduction, physical activity, weight loss, DASH diet, and reduced dietary sodium consumption may be useful for increasing the proportion of US adults with normal BP.
Current smoking was associated with a higher prevalence of normal BP among US adults ≥65 years of age. While this association may be due to current smokers having a lower BMI compared with former and never smokers, it may be due to current smokers with elevated BP or hypertension dying at younger ages than nonsmokers. Also, this may be a chance finding as smoking was associated with a lower likelihood of having normal BP in US adults 45–64 years of age and there was no association for those 18–44 years of age.
An analysis of data from the Multi-Ethnic Study of Atherosclerosis suggested that SBP as low as 90 mm Hg may be associated with a lower risk for cardiovascular disease when compared with higher SBP levels still within the range considered normal.24 Additionally, in the JHS, maintaining normal BP over 8 years of follow-up was associated with a lower incidence of cardiovascular disease, including coronary heart disease, stroke, or heart failure, compared with those with elevated BP/hypertension (4.5 vs. 16.4 events per 1,000 person-years) over the next 6 years.2 In the CARDIA study, participants with a low-normal BP trajectory over 25 years, from young adulthood through midlife, had a lower prevalence of coronary artery calcification score ≥100 Hounfield units.1 In a cross-sectional analysis in 4,666 Korean adults who participated in a general health checkup, there was a linear relationship between higher BP and an increased prevalence of coronary artery plaque, starting from an SBP of approximately 80 mm Hg and a DBP of 40 mm Hg.25 In the current study, US adults ≥65 years of age with normal BP vs. elevated BP/hypertension were less likely to have diabetes, albuminuria, a history of ASCVD, and heart failure.
Strengths of the current study include providing nationally representative prevelance estimates for the noninstitutionalized US population. BP was measured following a standardized protocol with rigorous quality control procedures. The extensive data collection in NHANES allowed for the investigation of several lifestyle factors for maintaining normal BP and health conditions associated with normal BP. The results of the current study should be interpreted in the context of its limitations. It was based on a cross-sectional design and maintenance of normal BP over time could not be evaluated. Although NHANES includes a large sample size, only 88 participants ≥75 years of age had normal BP and participants 65–74 and ≥75 years of age had to be grouped to produce reliable statistics. Data on diet were missing for roughly 20% of participants. NHANES did not enroll institutionalized adults including those residing in nursing homes. NHANES relied on BP from a single visit and out-of-office BP measurements were not available.
In conclusion, the current study suggests that moderate or no alcohol consumption, physical activity, overweight and normal weight vs. obesity, and a diet consistent with the DASH are associated with normal BP among US adults ≥65 years of age. US adults ≥65 years of age with normal BP were less likely to have adverse health conditions including diabetes, albuminuria, ASCVD, and heart failure. A 2020 Call-to-Action from the US Surgeon General emphasized the need to improve BP control among US adults with hypertension.21 These efforts should be extended to the prevention of elevated BP and hypertension.
Supplementary Material
Funding
Dr Shakia T. Hardy was supported through grant R01HL139716 from the National Heart Lung Blood Institute (NHLBI). Dr Kathryn Foti was supported through grant T32 HL007024 by NHLBI. Dr C. Barrett Bowling was supported through grant R01HL133618 from NHLBI and R01AG062502 from the National Institute of Aging. Dr Paul K. Whelton was supported by a National Institutes of General Medical Sciences (NIGMS) P30GM103337 COBRE award. Dr Byron C. Jaeger was supported by R01HL117323 from the NHLBI.
DISCLOSURE
The authors declared no conflict of interest.
This manuscript was sent to Guest Editor, Hillel W. Cohen, MPH, DrPH for editorial handling and final disposition.
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