Study designs of evaluations included in the review
To be included, the studies had to be randomised controlled trials with a follow-up of at least 2 years and a sample size of at least 200. Two studies were excluded because alternate allocation was used to assign the treatment to recruited patients.
Specific interventions included in the review
To be included, the studies had to compare CCBs with placebo or another hypertensive. The drugs included in the review were: atenolol, amiloride, amlodipine, clonidine, chlorthalidone, diltiazem, enalapril, felodipine, fosinopril, hydrochlorothiazide, isradipine, lisinopril, metoprolol, nicardipine, nifedipine, nisoldipine, nitrendipine, pindolol, trichlormethiazide, and verapamil.
Participants included in the review
Patients with hypertension were eligible for inclusion. The presenceor absence of co-morbidities was not specified in the inclusion criteria. Hypertension was defined differently in each of the 10 studies, with the diastolic blood-pressure ranging from greater than 90 mmHg to at least 105 mmHg, and/or a systolic blood-pressure ranging from greater than 140 mmHg to greater than 160 mmHg. Two studies were of patients with diabetes mellitus. One study was of high-risk patients with hypertension and one other CV risk factor (e.g. diabetes, hypercholesterolaemia or coronary heart disease). The studies were of patients in the USA, Europe, Israel and Japan. No age limit was specified in the inclusion criteria, but the patients were aged 40 years or above; no upper age limit was specified.
Outcomes assessed in the review
To be included in the review, the studies had to include CV events as a primary or secondary end point. The primary end points of the included studies were: blood-pressure; mortality; progression of carotid artery intimal-medial thickness; CV complications; 24-hour creatinine clearance; total serum cholesterol and blood sugar control; total stroke; CV mortality; composite end point of fatal and nonfatal stroke, fatal and nonfatal myocardial infarction, and other CV death; composite end point of death from any CV or cerebrovascular cause, nonfatal stroke, myocardial infarction, and heart failure.
How were decisions on the relevance of primary studies made?
The authors do not state how the papers were selected for the review, or how many of the reviewers performed the selection.