Rationale, study design and implementation of the COLM study: the combination of OLMesartan and calcium channel blocker or diuretic in high-risk elderly hypertensive patients

The COLM study is an investigator-initiated trial comparing the combination therapy using an angiotensin II receptor blocker (ARB), olmesartan, and a calcium channel blocker (CCB) with that using an ARB and a diuretic in high-risk elderly hypertensive patients. Here we describe the rationale and study design. Olmesartan was administered concomitantly with a long-acting dihydropyridine CCB (ARB/CCB group) or with a low-dose diuretic (ARB/diuretic group) to elderly hypertensive patients with a history of or risk factors for cardiovascular disease. Cardiovascular morbidity and mortality as a primary end point were compared between the two groups, with the target blood pressure (BP) being < 140 mm Hg for systolic BP and < 90 mm Hg for diastolic BR Safety and tolerability will also be investigated. A total of more than 4000 patients were recruited and will be followed up for at least 3 years.