Comparison of the Prevalence of Hypertension Using Three Proposed Criteria: Single-centre Study from a Southeast Asian Wellness Centre

Hypertension is a leading cause of cardiovascular morbidity and mortality worldwide. Its global burden is estimated at approximately 1.4 billion individuals and, at the current rate, will exceed 1.6 billion by 2025.¹ Based on the latest nationwide survey (PRESYON-4), the prevalence rate of hypertension in the Philippines is 37%, with 34% of those having grade 1 hypertension and 26% having isolated systolic hypertension.² The 2017 American College of Cardiology (ACC)/American Heart Association (AHA) and the 2023 European Society of Hypertension (ESH) guidelines are two of the most contemporary and widely used guidelines in the diagnosis and management of hypertension.^3,4 A comparison of these two guidelines reveals that the ACC/AHA guidelines use a lower blood pressure (BP) threshold of 130/80 mmHg or higher to diagnose hypertension in the general population, whereas the ESH guidelines retain a threshold of 140/90 mmHg for the requirement of antihypertensive medication.^3,4 The cut-off in the 2023 ESH guidelines is the same as that in the 2020 Philippine guidelines.⁵ Previous studies have shown that a larger population of patients is diagnosed with hypertension using the 2017 ACC/AHA guidelines compared with the 2018 European Society of Cardiology/ESH guidelines.^6,7 Depending on which classification is adopted, this may potentially impact therapeutic decisions, resulting in the under- or overtreatment of hypertensive patients.

In the Philippines, the PRESYON-4 nationwide survey defined hypertension as having a BP of 140/90 mmHg based on the 2018 European Society of Cardiology/ESH guidelines.² However, there are no local data on the prevalence of hypertension according to the ACC/AHA versus ESH and Philippine guidelines. The differences in these guidelines have implications for the true prevalence of hypertension, the burden of treatment costs and the true benefit and/or risk of aggressive BP lowering. BP classification also differs among the three guidelines, and physicians may have a preferred guideline classification that they use in their clinical practice.

The aims of this study were to determine the prevalence of hypertension according to the 2017 ACC/AHA, 2023 ESH and 2020 Philippine guideline classifications, to describe the BP distribution by percentage according to category based on these three guidelines and to determine the BP control rates in treated hypertensive patients, including the type of medications used, as per the guidelines.

Methods

Population and Sample Size

Study participants were patients seen at the Wellness and Aesthetic Institute of The Medical City between January 2017 and December 2022 with a diagnosis of hypertension at the baseline assessment. The computed sample size was 205, using the Raosoft sample size calculator, which is based on a population of 437 patients recruited in the cross-sectional study by Aydogan et al.⁶ The wellness centre cohort consisted of patients who requested an executive medical check-up at The Medical City and who underwent a series of diagnostic tests at the Wellness and Aesthetic Institute and were assigned a consultation with a wellness physician. All known hypertensive patients, regardless of baseline BP at the clinic visit, were eligible for inclusion in the study. Patients with mental health conditions, malignancies and those aged <18 years were excluded.⁶

Methodology

This study was a retrospective analytical cross-sectional study. The electronic records (Microsoft Excel, Microsoft Word and Adobe Acrobat files) of the Wellness and Aesthetic Institute were reviewed. These records were based on the assessments of patients seen by a primary care physician with a subspeciality in internal medicine between January 2017 and December 2022. In all, 242 patients (40 per year) were randomly selected using an online randomiser (www.randomizer.org). Using the randomiser, each patient was assigned a unique number according to their sequence in the electronic records. When the assigned number for a patient did not meet the inclusion and exclusion criteria, every third patient from last selected was evaluated until one met the criteria and was included in the final selection. For example, if patient 1 did not satisfy the criteria, then the patient is not included. Then patient 4 will be evaluated and so forth until one meets the criteria.

Clinic BP was based on the documented BP taken at the time of the patient’s consult at the Wellness and Aesthetic Institute. Once the patient was seated and before entering the room for consultation, BP was measured by a nurse using a manual BP apparatus or a sphygmomanometer; there was only one BP reading in the medical record for each patient, with no indication of the number of readings or whether the reported value was an average of several readings. This BP value was used to reclassify patients as hypertensive based on the office BP cut-off values in the ESH, ACC/AHA and Philippine guidelines. Because the study population included only known hypertensive patients, the diagnosis of hypertension was based on the wellness physician’s BP measurement during clinical assessment and review of the patient’s own history. Information on baseline characteristics was gathered, including age, sex, clinic heart rate, BMI, waist circumference, smoking status and comorbidities, such as coronary artery disease, diabetes, dyslipidaemia, chronic kidney disease, chronic obstructive pulmonary disease, obstructive sleep apnoea, gout, fatty liver disease and migraine. Antihypertensive medications were also listed. Determinations regarding chronic kidney disease and dyslipidaemia were based on the estimated glomerular filtration rate (eGFR) and serum lipid profile. Data on other laboratory parameters, such as fasting blood sugar and uric acid, were also obtained.

This study was approved by the Institutional Review Board of The Medical City, Ortigas.

Statistical Analyses

All analyses were performed in Microsoft Excel 365. Patients were categorised according to the thresholds for hypertension diagnosis set by the three guidelines. Descriptive statistics were used to summarise patients’ demographic and clinical characteristics. Categorical variables are presented as percentages or frequencies and continuous variables are presented as the mean ± SD. The normality of distribution was determined for all continuous variables, including age, office BP, office heart rate, BMI, waist circumference, eGFR, lipid profile, fasting blood sugar and uric acid levels. Assuming equal variances, mean values were compared using a two-sample t-test, whereas the significance of differences in categorical variables was determined using a χ² test. The comparison of the overall hypertension prevalence based on the guideline classifications, the comparison of clinical characteristics based on the prevalence of hypertension between the ACC and the Philippine/ESH guidelines, and the comparison of controlled and uncontrolled hypertension were based on 95% CI, and statistical significance was set at p<0.05 (two-tailed).

Results

In all, 242 patients were analysed (Supplementary Table 1 ). The mean age of patients was 54.06 ± 9.95 years, and 65.29% of patients were men. Dyslipidaemia was the most common comorbidity (70.66%), followed by diabetes (30.17%), fatty liver disease (15.29%) and obstructive sleep apnoea (8.26%). Current smoking was registered for 15.29% of patients. Most patients had obesity (mean BMI 28.85 ± 6.05 kg/m²; mean waist circumference 97.87 ± 13.72 cm) according to the Asia Pacific classifications.⁸

After reclassifying patients according to the ESH, ACC/AHA and Philippines guidelines based on documented BP at the time of the consult at the Wellness and Aesthetic Institute, statistically significant differences in the overall prevalence of hypertension among those previously diagnosed with hypertension were evident (p<0.00001; Table 1). Based on the 2023 ESH guidelines, 28.93% (n=70) of the 242 patients in the study were diagnosed with hypertension (systolic BP [SBP] ≥140 mmHg and/or diastolic BP [DBP] ≥90 mmHg). According to the 2020 Philippine guidelines, using the same criteria of BP ≥140/90 mmHg, the same percentage of patients were diagnosed with hypertension. Conversely, based on 2017 ACC/AHA guidelines, in which hypertension is defined as SBP ≥130 mmHg or DBP ≥80 mmHg, 82.64% (n=200) of the patients were classified as hypertensive. Over time, the prevalence of hypertension appears to be consistently high, ranging between 75% and 87.5% of the study group per year (n=40) when using the ACC/AHA guidelines, and lower at 21.95–36.59% with the ESH and Philippine guidelines. There was no consistent decreasing trend in the prevalence of hypertension when using the ACC/AHA guidelines, but if the ESH and Philippine guidelines were used the prevalence of hypertension appeared to exhibit a decreasing trend from 2020 to 2022 (Figure 1).

Based on BP classification according to the ESH guidelines, most patients had normal BP (42.98%). Among those classified as hypertensive, 53 (21.9%) patients had Grade 1 hypertension, 15 (6.2%) had Grade 2 hypertension, 2 (1.24%) had Grade 3 hypertension, 10 (4.13%) had isolated systolic hypertension and 32 (13.22%) had isolated diastolic hypertension. However, based on the ACC/AHA guidelines, most patients were classified as having hypertension, with 130 (53.72%) patients in Stage 1 and 70 (28.93%) in Stage 2. There was no stratification of hypertension in the Philippine guidelines. Despite this, 138 (57.02%) patients had borderline BP according to the Philippine guidelines. This contrasts with the lower percentages of patients with high-normal BP (34 patients, 14.05%) and elevated BP (8 patients, 3.31%) based on the ESH and ACC/AHA guidelines, respectively (Supplementary Table 2).

Across all three guidelines, most patients were classified as having uncontrolled hypertension. Based on a target BP of <130/80 mmHg in the ACC/AHA and Philippine guidelines, 200 (82.64%) patients were found to have uncontrolled hypertension. This is not far from the 199 (82.23%) patients who did not reach an SBP target of <140 mmHg, based on the ESH guidelines. Between 2017 and 2022, the percentage of uncontrolled hypertension was lower in 2021 and 2022 (Figure 2).

Most patients (n=110, 45.45%) were maintained on a single antihypertensive medication, with the most commonly used being an angiotensin receptor blocker (ARB), followed by calcium channel blockers (CCB) alone, a single-pill combination of ARBs and CCB and then β-blockers. In 2017, the most common antihypertensive was an ARB, but in 2022, ARB alone, ARB+CCB and CCB alone were equally common, with a trend towards the use of ARB+CCB from 2020 to 2022 (Figure 3). Seventeen patients were not maintained on any antihypertensive medication. Of these 17 patients, four had elevated BPs with an SBP of 160–180 mmHg and/or a DBP of 100–120 mmHg. In the entire study group, only 19 patients (7.85%) were recommended antihypertensive medications at the clinic visit due to elevated BP, with two being advised to decrease the dosage of their antihypertensive medication due to low BP.

Using the BP targets for treatment of the ACC/AHA and Philippine guidelines as basis for controlled (n=200) hypertension, those with uncontrolled hypertension had a higher BMI (29.23±6.37 versus 27.02±3.75 kg/m²; p=0.031). Similarly, using the ESH guideline definitions of controlled (n=43) and uncontrolled (n=199) hypertension, BMI was higher in the group with uncontrolled hypertension (29.24 ± 6.39 versus 27.00 ± 3.71 kg/m²; Supplementary Table 3).

Patients classified as hypertensive using the ACC/AHA guidelines had higher total cholesterol (p=0.014) and non-HDL cholesterol (p=0.010) than those classified as hypertensive using the ESH and Philippine guidelines. A higher percentage of patients classified as hypertensive using the ESH and Philippine guidelines were prescribed antihypertensive medications at the clinic visit than those classified as hypertensive using the ACC/AHA guidelines (14/70 [20%] versus 16/200 [8%]; p=0.006; Supplementary Table 4).

Comparing patients with controlled versus uncontrolled hypertension revealed no significant differences in age, office heart rate, waist circumference, smoking history, LDL cholesterol, fasting blood sugar or eGFR. No significant difference was inferred for comorbidities or types of antihypertensive medication, because one patient could have more than one comorbidity or medication.

Discussion

In this study, the prevalence of hypertension was significantly higher when using the ACC/AHA guidelines than the ESH and Philippine guidelines. The ESH and Philippine guidelines used the same cut-off BP to classify hypertension (i.e. BP ≥140/90 mmHg), whereas the ACC/AHA guidelines used a lower BP level (≥130/80 mmHg).^3–5,9 These results coincide with those of previous studies comparing the ACC/AHA and ESH guidelines.^6,7

In 2021, the PRESYON-4 survey reported that the prevalence of hypertension in the Philippines, using the definition in the 2018 European Society of Cardiology (ESC) guidelines, was 37%.² However, in the present study, the prevalence of hypertension using the 2023 ESH guidelines was lower, at 28.93%. Of note, there was no difference in BP cut-offs to define hypertension between the 2018 ESC and 2023 ESH guidelines, but isolated diastolic hypertension has been added in the latest ESH guidelines.⁴ In the present study, Grade 1 hypertension was still predominant, compared with Grade 2 and Grade 3 hypertension, as also reported in PRESYON-4.²

Using all three guidelines, majority of the study population had uncontrolled hypertension.^3–5 The ACC/AHA and Philippine guidelines use the same BP target of <130/80 mmHg for treatment, whereas, in general, the ESH guidelines use a target of SBP of <140 mmHg. All three guidelines also have specific therapeutic BP goals for the elderly and for those with comorbidities. In the present study, most of the study population ranged in age from 18 to 64 years. Of note, although the general BP target of an SBP of <140 mmHg is used, the ESH guidelines specify that the target for those aged 18–64 years should be <130/80 mmHg.^4,9 This probably explains why the percentage of those with controlled and uncontrolled hypertension is similar across all three guidelines.

Many cardiovascular risk factors are associated with hypertension.¹ In the present study, the only significant demographic and cardiovascular risk factor when comparing those with controlled and uncontrolled hypertension was obesity. Obesity, other than age and family history, was also one of the risk factors associated with hypertension in the study of Aydogan et al., but was only significant based on the 2018 ESH/ESC guidelines and not the 2017 ACC/AHA guidelines.⁶ Demographic and cardiovascular risk factors associated with hypertension diagnosis may vary with changes in hypertension thresholds.⁶ In the present study, obesity was significantly associated with hypertension using all three guidelines. This may be due to the percentage of those with controlled and uncontrolled hypertension being similar across all three guidelines, for which the target BP is <130/80 mmHg in the majority of the population. Hence, obesity management is crucial to reduce cardiovascular risk in patients with hypertension. Strategies to reduce body weight and BP, which include dietary modification and physical activity, should be emphasised.¹⁰ Angiotensin-converting enzyme inhibitors and ARBs should be regarded as first-line treatment in individuals with obesity and hypertension.¹⁰ Patients with obesity also require a larger number of medications, thereby making BP control difficult.¹¹

In addition to obesity, mean total cholesterol and non-HDL cholesterol levels were associated with hypertension across all three guidelines. The higher cholesterol values using the ACC/AHA guidelines compared with the ESH and Philippine guidelines and the lower BP cut-off to define hypertension using the ACC/AHA guidelines imply perhaps higher BP levels do not necessarily translate to higher total cholesterol and non-HDL levels. However, more people classified as hypertensive tend to have higher total cholesterol and non-HDL cholesterol. More importantly, non-HDL cholesterol is reported in the recent ESH guidelines as an additional parameter for risk stratification in patients with hypertension.⁴ This shows how dyslipidaemia management should go beyond lowering LDL cholesterol and should support the concept of risk-based lipid-lowering treatment.¹² In fact, one study showed that higher non-HDL cholesterol levels were associated with cardiovascular disease than LDL cholesterol levels, which may explain the association of non-HDL cholesterol with hypertension in this study.¹³

Most of the present study population had uncontrolled hypertension and the percentage of antihypertensive medications prescribed during clinic visits on record review was suboptimal. One reason may be due to differences in BP targets used by the wellness physician. A physician may classify a patient as Stage 1 hypertension in the ACC/AHA guidelines but use an SBP target of <140 mmHg in the ESH guidelines. These discrepancies may lead to a lack of prescription or uptitration of additional antihypertensive medications, and the physician may focus on lifestyle and dietary advice. Another possible explanation for the low prescription of new medications at clinic visit is that internal medicine physicians may be less likely to prescribe CCBs, β-blockers and ACE inhibitors than a cardiologist.¹⁴

Based on the Philippine guideline classification, most of study population had borderline BP (120–139/80–89 mmHg), which comprises part of the subset of patients who are already classified as having elevated BP (SBP 120–129 mmHg and DBP <80 mmHg) and Stage 1 hypertension (SBP 130–139 mmHg or DBP 80–89 mmHg) in the 2017 ACC/AHA guidelines. With regard to treatment, therapeutic disparities may arise as to whether additional medication should have been given at this point and what BP target needs to be achieved. Although both the ACC/AHA and Philippine guidelines recommend lifestyle intervention at this stage, the ACC/AHA guidelines take into account overall atherosclerotic cardiovascular disease risk, as determined by a risk calculator, to indicate the start of pharmacological monotherapy with a lower BP cut-off (130/80 mmHg).¹⁵ The Philippines has yet to create and adopt its own cardiovascular disease risk assessment tool. Conversely, the Philippines guidelines, like other Asian guidelines, have patterned themselves after European guidelines by adopting and recommending specific risk groups or categories for hypertension management.¹⁵

All three guidelines recommend initial single-pill combination therapy as the standard treatment.^3–5 However, it appears that its application in real-world practice is low.¹⁶ In the present study, most patients were given monotherapy with ARBs, which is similar to the results of PRESYON-4.² This preponderance of monotherapy and clinical inertia can hinder successful pharmacological management of hypertension.¹⁷ It should also be noted that there seemed to be an increased use of the single-pill combination of an ARB+CCB from 2020 to 2022, which incidentally coincided with the improved control of hypertension in 2021 and 2022, probably reflecting increased awareness of the latest guidelines prescribing combination therapy. It has been shown that initiation of hypertensive treatment using a single-pill combination may improve adherence to antihypertensive medication, eventually leading to better BP control and fewer composite cardiovascular events.^18,19

This study has many limitations. The study population is from a single centre, limiting the generalisability of the results. Because of this, the lower prevalence of hypertension compared with that reported in PRESYON-4 study may be biased. To clarify, this study’s results represent diagnostic reclassification under different guidelines rather than true prevalence because the individuals included in the study were known to have hypertension. Given that the study population already includes all known hypertensive individuals, we relied on a single clinic BP reading to identify any inconsistencies in hypertension classification across the three guidelines. In addition, because the wellness physician relied solely on clinical history and current antihypertensive medications to diagnose hypertension, it was unknown whether these patients underwent other diagnostic procedures, such as home BP monitoring or 24-hour ambulatory BP monitoring, to confirm a diagnosis of hypertension, as recommended by guidelines. The compliance rate to medications for the high percentage of uncontrolled hypertension cannot be accounted for because it was not measured in this study. In addition, management of hypertension is at the discretion of the wellness physician, who may use different hypertension guidelines and may refer the patient back to their own attending physician or cardiologist for further management. The true prevalence of hypertension in our setting, with the newly released guidelines and classifications, is uncertain.

To the best of our knowledge, this study is the first of its kind to compare the local Philippine classification with those of the ACC/AHA and ESC. Our findings provide insights into the prevalence of hypertension, which can differ depending on the classification used and may potentially alter approaches to management. Future adequately powered multicentre studies are recommended to determine the potential therapeutic impact of these different guideline classifications in clinical practice.

Conclusion

The prevalence of hypertension is higher when using the ACC/AHA guidelines compared with the local Philippine and ESC guidelines. These differences may potentially impact clinicians’ decision-making regarding therapeutic interventions to achieve adequate BP control in our setting.

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