Japan Morning Surge -1 (JMS-1) Study: Effect of predominant morning BP control on target organ damage in medicated morning hypertensive patients

Cardiovascular events occur more frequently in the morning than at other times of the day, and morning high BP is a risk factor for cardiovascular disease. However, the effects of a predominant reduction in morning BP on hypertensive target organ damage and subsequent cardiovascular disease have not been fully investigated. We here present the protocol of the Japan Morning Surge -1 (JMS-1) Study in which we attempt to clarify the hypothesis that predominant reduction in morning BP using add-on bedtime administration of an alpha-adrenergic blocker, doxazosin, will reduce hypertensive target organ damage. This study was initiated in August 1, 2003, and 582 patients had been recruited by November 30, 2004. The baseline data will be presented at the Scientific Meeting of the American Society of Hypertension in 2005. We will recruit 600 hypertensive patients, whose morning systolic BP levels measured by home BP monitoring are >135mmHg while on antihypertensive medication for at least 3 months. The study patients are recruited from 20 clinics in Japan, and the independent study center randomly divides these patients into the strict morning BP control group who receive bedtime administration of doxazosin (doxazosin group), and a control group who are followed without any add-on medication (control group). In the doxazosin group, doxazosin is initiated at 1 mg hs and titrated to 4 mg for 3 months to achieve morning systolic BP<135mmHg. When morning systolic BP remains >135mmHg 3 months after doxazosin initiation, a β blocker is added. We assess hypertensive organ damages using urinary microalbumin excretion and brain-type natriuretic peptide in all the participants of both groups at the baseline and 6 months after the randomization. As a substudy, we also assess left ventricular mass index, pulse wave velocity, and augmentation index. The Japan Morning Surge -1 (JMS-1) Study will clarify the effects of bedtime add-on therapy of doxazosin on morning BP control and the regression of hypertensive target organ damage in patients with uncontrolled morning hypertension.