Hypertension

Hypertension is an important contributor to cardiovascular disease. The 2020 National Population Health Survey showed an increasing trend in the crude prevalence of hypertension among Singapore residents aged between 18 to 74 years, from 24.2% in 2017 to 35.5% in 2019-2020¹.
Blood pressure category is defined by the highest level of blood pressure, whether systolic or diastolic².
Treatment decisions are individualised for each patient and based on an assessment of overall cardiovascular risk.

Clinical Approach[3]

Recommended considerations when taking blood pressure measurements for diagnosis:

Allow the patient to sit or lie down for at least 3 minutes before measuring the BP.
Use the correct size BP cuff.
Take an average of 2 seated blood pressure (BP) measurements separated by 2 minutes. If the first two readings differ by 5mmHg or more, further readings should be obtained and averaged.
Repeat BP measurements on at least 2 separate occasions.
Consider home BP monitoring, where appropriate.

Diagnose hypertension if systolic ≥ 140 mmHg or diastolic ≥ 90 mmHg. For home blood pressure monitoring, use 135/85 as the cut-off for hypertension.

Table 1: Initial Screening Blood Pressure (BP) (Average of 2 or More Readings)

Systolic BP (mmHg)	Diastolic BP (mmHg)	Category	Recommended Action
<130	<85	Normal	“Normal BP". Advise BP check biennially
130 – 139	85 – 89	High-Normal BP	Advise lifestyle modification. Check BP annually or more frequently if cardiovascular risk factors are present.
140 – 159	90 – 99	Grade 1 Hypertension	For those without cardiovascular risk factors, try lifestyle modifications first for 3 – 6 months (shorter for those with cardiovascular risk factors). For those at high risk with established cardiovascular or renal disease, diabetes mellitus or target organ damage, initiate drug treatment with lifestyle measures at the same time
160 – 179	100 – 109	Grade 2 Hypertension	For those at low risk with 0 to 2 cardiovascular risk factors, can try lifestyle modification first for several weeks; otherwise, initiate drug treatment with lifestyle measures at the same time.
≥ 180	≥ 110	Grade 3 Hypertension	Initiate drug treatment with lifestyle measures at the same time.
≥ 140	< 90	Isolated Systolic Hypertension	Isolated systolic hypertension is graded according to the same ranges of systolic BP as the above, and the corresponding recommendations apply.

Hypertensive emergency:

Diagnose if high blood pressure (often > 180/110 mmHg) associated with signs or symptoms of acute end organ damage or dysfunction.

History, examination and investigations

Important Note - determine whether there is/are

Secondary causes for the hypertension
Target organ damage
Other cardiovascular risk factors present

Management[3]

Blood Pressure Treatment Targets

1. General:

< 140/90 mmHg in patients < 80 years old.
< 150/90 mmHg in patients ≥ 80 years old (do not decrease diastolic BP to < 60 mmHg).

2. Special conditions:

< 140/80 mmHg in patients with diabetes mellitus
≤ 130/80 mmHg in patients with proteinuria (both diabetic and non-diabetic patients)
< 150/100 mm Hg in pregnant patients without target organ damage (do not decrease diastolic BP to < 80 mm Hg)
< 140/90 mmHg in pregnant patients with target organ damage

The Cardiovascular Disease (CVD) Risk Calculator may be used to determine the BP targets of patients.

Recommended Care Components²

Table 2. Recommended Care Components

Recommended Care Components	Minimum Frequency*	Remarks
Blood Pressure Measurement	Twice a year
Weight and BMI Assessment	Twice a year	Keep <23kg/m² (For Non-Asian population, keep BMI <25 kg/m²)
Kidney Assessment Serum Cr and/or eGFR, and Urine Albumin-Creatinine Ratio (uACR) or Protein-Creatinine Ratio (uPCR)	Annually	If patient also has DM, Angiotensin Converting Enzyme (ACE) inhibitor or Angiotensin Receptor Blocker (ARB) are preferred antihypertensives to slow progression of diabetic nephropathy Annual screening of: Serum Cr and/or eGFR and uACR in all patients, or uPCR if significant levels of proteinuria
Smoking Assessment	Annually for smokers; Once-off for non-smokers, unless there is a change in smoking habit	Assessment on smoking habits (estimated sticks/day; zero for non- or ex-smoker) and provide smoking cessation counselling
Lipid Profile	At baseline	All patients should be stratified for their risk of developing future coronary events⁵. Targets of treatment should be personalised by levels of risk. Please refer to Care Protocol for Lipid Disorders
Cardiac Assessment	At diagnosis before initiating medications	Includes baseline ECG

*More frequently if clinically indicated.

Non-pharmacological^3,4

Where resources are available, consider the roles of other primary care team members – nurse counsellors and primary care coordinator.

Regular exercise
Smoking cessation
Weight reduction
Reduction of alcohol intake
Reduction of sodium intake. Refer to High Blood Pressure: Healthy Eating Guide. (e.g. Dietary Approaches to Stop Hypertension (DASH) diet)
Reduction of stress

*Please refer to BMI Control and Smoking Cessation Care Protocols for lists of programmes.

Pharmacological⁴

Figure 1: Drug Choices

Drug Combinations

Beta-blocker + ACE-I / ARB does not produce synergistic BP reduction
ACE-I + ARB decreases GFR in CKD patients and should be avoided. (Consider monitoring serum creatinine and potassium levels for all patients started on either ACE-I or ARB)
Beta-blocker + diuretic increases risk of developing diabetes mellitus
Beta-blocker + non-dihydropyridine CCB (e.g., diltiazem) increases risk of bradycardia and AV Block and should be avoided

Considerations for Specialist Referral²

Specialist Referral Recommended

Emergency or urgent treatment indicated e.g., malignant hypertension, hypertensive cardiac failure or other impending complications.
Hypertension difficult to manage e.g., unusually labile BP, hypertension refractory to multiple (3 or more) drug regimens.
Suspected secondary hypertension i.e., hypertension due to an underlying cause, such as hyperaldosteronism.
Hypertension in special circumstances e.g., pregnancy, young children.

Consider Specialist Input

Young hypertensive patients who are less than 30 years old.
Patients suspected to have secondary causes of hypertension.

GPs may use the CHAS Medical Referral Form to make subsidised SOC referrals and the GPFirst Referral Form for Emergency Department referrals. These can be found on Healthier SG compatible GP CMS and on the PCDS web-portal.

Data Submission

The following data fields should be documented in GPs' case notes as part of good clinical practice for all patients enrolled to their practice.

Submission of data fields marked with asterisks* is required for subsidy claims and Healthier SG payments.

Blood Pressure

Systolic BP (mmHg)*
Diastolic BP (mmHg)*
Date*

Blood Glucose

HbA1c (%) or Fasting Plasma Glucose (mmol/L or mg/dL)
Date

Lipid Profile

LDL-Cholesterol (mmol/L or mg/dL)
HDL-Cholesterol (mmol/L or mg/dL)
Triglycerides (mmol/L or mg/dL)
Total Cholesterol (mmol/L or mg/dL)
Date

Weight

BMI (kg/m²), calculated from height*, weight*
Waist Circumference (in cm; optional field to fill)
Date*

Kidney Assessment

Serum creatinine (mol/L)* or eGFR (ml/min/1.73m²)*
Urine ACR (mg/mmol)* or Urine PCR (mg/mmol)*
Date*

Smoking History

Smoking Status* [Never smoker, Ex-smoker, Current Smoker]
Year started smoking (if smoker)
No. of sticks smoked/day* (if smoker)
State of change: (i) Pre-contemplation, (ii) Contemplation, (iii) Preparation (iv) Action, OR (v) Maintenance

Financing

CHAS/PG/MG cardholders who are Healthier SG enrolees would be eligible for the Healthier SG Chronic Tier, which provides percentage-based subsidies for a whitelist of drug products at capped selling prices. When making claims, GPs will need to submit the quantities and selling prices for each whitelisted drug product prescribed.

Details on the GP annual service fee for enrolees with hypertension can be found in the Healthier SG Letter of Appointment. Enrolment Programme Agreement.

References