Background: Hypertension is a serious public health problem responsible for significant mortality and morbidity from cardiovascular disease. In Singapore, 1 in 4 adults age 30 years or older suffer from hypertension. Nearly half of these patients have uncontrolled hypertension and only 50% of individuals are on antihypertensive treatment. Our study aims to evaluate the effectiveness, cost effectiveness and impact on medication adherence of a well-structured program using multicomponent intervention for hypertension control aimed at overall cardiovascular risk reduction among individuals with hypertension attending the polyclinics in Singapore, compared to existing services. Such a program is expected to be cost-effective in terms of improving hypertensive individuals' outcomes, and to be potentially scalable and sustainable.

Methods/design: Cluster randomized trial of 8 of the nine SingHealth Polyclinics randomized to intervention or usual care (4 each) and followed up for 2 years post randomization

Intervention: The structured multicomponent primary care program comprises of: 1) algorithm-driven antihypertensive treatment for all hypertensive individuals and using fixed-dose combination (FDC) and lipid-lowering medication for high-risk hypertensive individuals, 2) motivational conversation for high-risk hypertensive individuals, 3) Follow-up of all hypertensive individuals on improving blood pressure (BP) as a primary outcome and other cardiovascular risk factors as a secondary outcome, and 4) discounts on FDC antihypertensive medication

Usual care: The participants attending polyclinics randomized to usual care will continue to receive treatment from the health providers according to existing practices. The hypertensive individuals will also continue to pay for the services (physician or nurse consultation) as per their existing model of reimbursement.

Participants: A total of 1000 participants will be recruited, 125 from each of the 8 polyclinics. Recruitment will be in batches of 4 and 4 clinics sequentially (balanced by randomization group).

Outcomes: All hypertensive individuals will be assessed by trained outcomes assessors independent to treatment at baseline, 1-year and 2-yeat post randomization. The primary outcome will be the change in systolic blood pressure from baseline to 2 years. Primary Cost-Effectiveness measures will be- 1) Incremental cost per mm Hg systolic BP reduction from baseline to end of follow-up at two years post randomization; 2) incremental cost per projected CVD disability adjusted life years (DALYs) averted and quality adjusted life years (QALYs) saved, and 3) incremental cost per change in cardiovascular risk score from baseline to final follow-up at two-year post. The impact of effect on adherence to antihypertensive and lipid medication will be measured using data on adherence obtained from polyclinic pharmacy records and clinic notes. An average of percent adherence to antihypertensive and lipid lowering will be computed as a composite score. The change in percent composite adherence to antihypertensive and lipid medications from baseline to follow up will be compared between the intervention and control groups.

Inclusion Criteria:

• 40 years or older
• Singapore citizens or Permanent Residents
• Visiting the recruiting polyclinic at least twice during the last 1 year
• Individuals with a diagnosis of hypertension (systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg on two or more prior visits; physician diagnosed hypertension, or on antihypertensive medications) and uncontrolled blood pressure (systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg)

Exclusion Criteria:

• Active systemic illness including fever, recent hospitalization (i.e. during last 4 months),
• Clinically unstable heart failure or advanced kidney disease {estimated CKD-Epi glomerular filtration rate (GFR) <40 ml/min/1.73m2 or nephrotic range proteinuria (i.e. 3g/d or more)},
• Known liver disease,
• Pregnancy or breastfeeding
• Any other major debilitating disease or mental illness that precludes validity of informed consent