This trial aims to evaluate the effectiveness of a guideline-based decision support system for hypertension management by physicians at primary health care (PHC) centers in China in order to improve the delivery of appropriate treatment and blood pressure (BP) control for hypertensive individuals.

The LIGHT trial aims to assess the effectiveness of decision support system (DSS) for hypertension treatment in cluster clinics. At each stage, the main randomization will occur at the PHC center level. During the first 3 months (baseline period), the physicians at all sites will use an electronic data collection system to collect information about the individuals who attend the clinic. After site randomization, physicians at control sites will continue to deliver usual care, and physicians at intervention sites will receive training and support on the use of the DSS. And the DSS will recommend antihypertensive medications according to the assigned protocol. All individuals will be asked to attend the clinic at least once every 3 months.

Inclusion Criteria for Sites:

1. At least one drug available from each of the four classes of recommended antihypertensive drugs are provided at clinic:

   • A: Angiotensin-converting enzyme inhibitors (ACEI; e.g., captopril and nalapril) or angiotensin receptor blockers (ARB; e.g., losartan and valsartan)
   • B: β-blockers (e.g., atenolol and metoprolol)
   • C: Calcium antagonists (e.g., nitrendipine, nifedipine, and amlodipine)
   • D: Diuretics (e.g., hydrochlorothiazide and indapamide)

2. Has an outpatient clinic for hypertension treatment and staff willing to take part in the study

3. Electronic data collection system is routinely used at clinic for hypertension management

4. At least 100 individuals with hypertension can attend the clinic every 3 months.

Inclusion Criteria for Visits:

1. Scheduled or unscheduled visit for hypertension treatment or prescription for antihypertensive medications
2. Visit for elevated blood pressure or adverse effect of antihypertensive medications
3. Visit for other cardiovascular diseases such as diabetes, stroke, PAD, or newly diagnosed of CKD, CAD and heart failure regardless of individuals' blood pressure level.

Inclusion Criteria for Participants:

1. Age ≥18 years
2. Local resident of the community/township who attend the PHC clinic for hypertension management
3. Established diagnosis of essential hypertension (defined as systolic blood pressure≥140 mmHg, diastolic blood pressure ≥90 mmHg, or both, measured on at least 3 separate visits; or currently taking antihypertensive medications)
4. Taking 0-2 types of antihypertensive medications (not including B)

Exclusion Criteria for participants:

1. Patients with SBP≥180 mmHg and/or DBP≥110 mmHg
2. History of coronary heart disease (i.e., angina, MI, coronary artery bypass grafting [CABG], percutaneous coronary intervention [PCI], >50% stenosis of coronary artery, or positive stress test)
3. Physician- diagnosed heart failure
4. Physician-diagnosed or self-reported CKD, estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 (if serum creatinine is available), or currently on dialysis
5. Physician-diagnosed secondary hypertension
6. Intolerance to at least two classes of antihypertensive medications among A, C or D
7. Other serious medical illness such as malignant cancer, hepatic dysfunction, et al
8. Currently at the acute phase of any disease
9. Subject is pregnant or breast feeding, or planning to become pregnant or breast feeding during study period