Study designs of evaluations included in the review
Randomised controlled trials (RCTs). Both placebo and active control designs were included, but the trials must have included at least 30 participants.
Specific interventions included in the review
Nine different monotherapies (atenolol, verapamil, enalapril, lisinopril, nifedipine, amlodipine, diltiazem, captopril and hydrochlorothiazide (HCTZ)) and one combination therapy (amlodipine/benazepril). Dosage and duration of the treatment varied between the drugs given, but to be included in the review, treatment duration had to be at least four weeks. The control was placebo or another drug.
Participants included in the review
People with mild to moderate essential hypertension defined as a baseline supine diastolic BP of 95 to 115 mm Hg. Studies which only included elderly participants (aged 60 years or over), or adolescents (aged less than 20 years) were excluded. Furthermore, studies were also excluded if they included patients with a history of poor control with prior antihypertensive therapy; if patients were allowed to continue concomitant antihypertensive medication during a placebo or baseline run-in phase; or if patients had significant concomitant diseases such as end-stage renal disease.
Outcomes assessed in the review
Change in supine diastolic BP from baseline to end of treatment; control of BP (defined as supine diastolic BP of 90 mm Hg or less and/or a decrease in supine diastolic BP of 10 mm Hg ore more); adverse effects and incidence of withdrawal due to adverse effects.
How were decisions on the relevance of primary studies made?
The article titles and abstracts from the MEDLINE search were initially screened for inclusion (not stated by how many reviewers). Selected articles were then subjected to subsequent review and were further evaluated by two independent reviews. Disagreements between the two reviewers were resolved by a third reviewer.