Guidelines for hypertension prevention, detection, evaluation, and management are intended to align with patients’ interests and improve their quality of care (1). As a result of emerging evidence, diagnostic thresholds were recently revised to detect complications associated with hypertension and intervene as early as possible (1). Early intervention has a variety of potential benefits, from a reduction in heart attacks, stroke, chronic heart failure, renal failure (2), and premature death (3), as well as substantial healthcare costs associated with treatment of the aforementioned complications (4). The revised hypertension diagnostic thresholds have considerably increased the prevalence of hypertension among young adults (5), adults over 20 yr (6), and mature adults (45–75 yr olds) residing in the United States (7). However, whether the revised diagnostic criteria have resulted in earlier identification of young adults at risk of complications associated with hypertension remains unknown.
This is a topic worthy of examination, as it will reinforce the importance of assessing hypertension in young adults who are typically presumed to be relatively healthy. The considerable increase in the prevalence of hypertension among young adults (5), as a result of the revised diagnostic thresholds, underscores the importance of confirming what aspects of health (i.e., fitness, adiposity, etc.) require improvement given both excess adiposity (8) and poor aerobic fitness (9) are associated with cardiovascular disease. Thus, the purpose of this study was to examine differences in fitness, anthropometrics, and blood profiles between those who were and those who were not reclassified as hypertensive using the revised hypertension diagnostic criteria. Findings will provide an indication of whether changes in guidelines enhance earlier identification of individuals at risk of diseases associated with hypertension than they would have been identified using the old guidelines.
Data were collected from students at a large Northeastern University in the United States who completed a preconsultation questionnaire online before completing an objective fitness assessment between September 2015 and April 2018. Students were recruited from general education health and wellness courses. Analyses were conducted on 2724 students who were categorized as prehypertensive under the JCN7 diagnostic criteria. All participants provided informed written consent, and trained technicians administered the tests. The Pennsylvania State University Institutional Review Board approved this study.
Before the fitness assessment, participants completed an electronic pretest questionnaire (BSDI, Califon, NJ), which was linked to the fitness assessment data using an identification number. All participants completed a health screening (10) before the fitness assessment, and participants requiring medical clearance were prevented from participating. Before visiting the facility for the fitness assessment, participants were instructed to abstain from caffeine for 8 h, alcohol for 24 h, smoking and food intake for 2 h, and exercise for at least 3 h. Blood pressure was the first measure taken for the fitness assessment, followed by body composition indices, before predicted aerobic fitness was assessed. Lipids and glucose were collected on a separate day after an 8- to 12-h overnight fast.
Participants self-reported age and sex in the preconsultation questionnaire.
Blood pressure was measured via auscultation by trained technicians using a Littmann II stethoscope and an appropriately sized ADC blood pressure cuff that was sized so that the bladder encircled 80% of the upper right arm. Before measurement, the subject sat for 5 min with their feet flat on the floor. Measurements were taken with the arm supported at heart level. Participants were categorized using JNC7 (11) and ACC/AHA (1) guidelines.
Body Composition Indices
Height and weight were measured using a scale with stadiometer (Health-O-meter is the brand, StartFragmentH-500KL Health-O-Meter Eye Level Digital Scale) and then used to calculate body mass index (BMI). Body fat percentage was calculated via bioelectrical impedance analysis (Bodystat 1500; Bodystat Ltd., Isle of Man, British Isles). Abdominal girth was assessed at the narrowest circumference between the umbilicus and the xiphoid process with a Gulick II tension-regulated tape measure.
Predicted Aerobic Fitness
Maximal oxygen uptake (V[Combining Dot Above]O2max) was measured using the YMCA Submaximal Cycle Ergometer test (10) while wearing a heart rate monitor. An estimate of maximal oxygen consumption was produced using the multistage model technique (12).
Lipids and Glucose
Total cholesterol, HDL, LDL, triglycerides, and fasting plasma glucose were assessed with a commercially available analyzer. Forty microliters of blood was collected from each participant via finger stick and injected into a Cholestech LDX lipid profile cassette (Cholestech LDX, Alere, Waltham, MA).
Descriptive statistics were computed to characterize the sample. Independent-sample t-tests examined differences in fitness, anthropometrics, and lipids and glucose between sexes and those diagnosed as having elevated blood pressure or stage 1 hypertension using the ACC/AHA who were prehypertensive using the JCN7. Odds ratios were calculated to examine whether the aforementioned variables were associated with a greater likelihood of being reclassified as having stage 1 hypertension. All analyses were split by sex because of previous findings that the change in diagnostic criteria influenced men and women differently (5). All analyses were run using the Statistical Package for the Social Sciences (version 25.0; IBM, Armonk, NY), with significance levels set at P < 0.05.
The mean age of participants was 21.3 ± 1.0 yr for all, 21.4 ± 1.0 yr for men (n = 1942, 71.3%), and 21.2 ± 0.9 yr for women (n = 782, 28.7%). Based on data collected from similar populations at the same university, participants were likely predominantly (~80%) non-Hispanic White (13).
Sex Differences in Fitness, Anthropometrics, and Lipids and Glucose
Fitness, anthropometrics, and lipid and glucose variables differed significantly between men and women (Table 1). Men had significantly higher BMI, abdominal girth, aerobic fitness, LDL, and glucose, whereas women had significantly higher body fat percentage, total cholesterol, HDL, and triglycerides.
Differences in Fitness, Anthropometrics, and Lipids and Glucose Based on Reclassification
Both men and women who were prehypertensive and then reclassified as having stage 1 hypertension were found to have significantly higher BMI, body fat percentage, and abdominal girth as well as lower aerobic fitness than those who were prehypertensive and remained classified as elevated (i.e., not reclassified). In addition, reclassified men had less favorable HDL, whereas reclassified women had less favorable LDL (Table 2).
Prediction of Reclassification
All anthropometric measures (BMI, body fat percentage, and abdominal girth) and aerobic fitness predicted reclassification for both men and women. The odds of being reclassified varied from 3% to 7% based on a one-unit increase in each predictor variable. For example, the odds ratios of 1.06 for BMI for men indicates that the odds of being reclassified increased by 6% with every 1 kg·m−2 increase in BMI. HDL was only predictive among men, and LDL was only predictive among women. Neither triglycerides nor glucose predicted reclassification for either sex (Table 3).
Findings demonstrate that the revised diagnostic criteria had the intended impact, resulting in those with poorer fitness and less favorable anthropometric profiles being classified as having hypertension. Moreover, within the confines of the current study, findings also alleviate doubts as to whether a considerable number of young adults reclassified as having hypertension are in need of intervention to reduce adiposity and improve aerobic fitness. Although findings are positive, it remains unclear how healthcare professionals can and will treat those with hypertension in light of the sudden increase in prevalence and the association between reclassification and unfavorable adiposity and fitness.
Although the burden on healthcare professionals to treat and prevent hypertension could be reduced by societal level or policy changes targeting lifestyle behaviors (1), healthcare professionals are undoubtedly a crucial component in hypertension treatment and prevention. Regardless, it is unreasonable to expect on-campus healthcare professionals to deliver nonpharmacological interventions given their time constraints (14). Thus, systems and supporting policies must be implemented to support alternatives such as referrals to experts in exercise and/or nutrition. For example, the physical activity vital sign is a tool that healthcare providers can use to identify individuals in need of advice regarding exercise (15), which is often difficult for college healthcare providers (16). However, the implementation of the physical activity vital sign and a referral system in a college setting is difficult without adequate support (17).
Furthermore, different approaches for men and women are warranted given tendency for young men to be worse when it comes to awareness, treatment, and control of hypertension compared with women (18). This, along with the finding that the change in hypertension guidelines affected young men the most (5), reinforces the importance of enhanced access to, and engagement with, medical care. Moreover, variations in dietary quality and physical activity between male and female college students (13) indicate that interventions should prioritize different behaviors when aiming to improve anthropometrics and fitness.
Although this study used data collected from young adults residing in the United States, findings raise questions as to whether the decision of the European Society of Cardiology and the European Society of Hypertension to leave their guidelines unchanged (19,20) is justifiable. At present, the difference between guidelines in the United States and Europe is attributable to safety concerns among those who set the European guidelines, namely, the risks of elderly individuals, i.e., those older than 65 yr, lowering their blood pressure levels too much (21).
As with previous studies (5), the generalizability of the findings of this study is limited by the predominantly non-Hispanic White sample. Thus, the replication of analyses in more diverse populations is warranted. Moreover, blood pressure was only measured once, but the new protocol of the American College of Sports Medicine (10) was adopted at the wellness center wherein measures were taken in the fall of 2018 after a data management system update. Measures of adiposity and aerobic fitness are not without their limitations. Although BIA is not the gold standard measure of adiposity, the inclusion of objectively assessed BMI and abdominal girth should alleviate some concerns given the results were similar for all three indicators of adiposity. With respect to aerobic fitness, conducting a full V[Combining Dot Above]O2max test would be ideal. However, doing so is unfeasible in a sample of this size, and testing guidelines set forth by the American College of Sports Medicine as a valid method of predicting cardiorespiratory fitness were followed as an alternative.
Those with poorer fitness and less favorable anthropometric profiles were more likely to be reclassified as having hypertension; thus, the revised hypertension diagnostic thresholds had the intended effect by allowing earlier identification of those in need of intervention. However, the capacity of healthcare professionals and the healthcare system in the United States to provide an increasing number of those diagnosed as having hypertension with treatment remains unclear. Further research is required to understand how those identified as having hypertension can receive the most time and cost-effective treatment to benefit both their short- and long-term health.
The authors acknowledge the faculty and staff of the Kinesiology Physical Activity Program, and the students who allowed the use of their data. None of the authors have a conflict of interest related to the present study. The results of the present study do not constitute endorsement by the American College of Sports Medicine.
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