Effects of Blood Pressure Drugs in Patients with Diabetes and Kidney Disease

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Effects of Blood Pressure Drugs in Patients with Diabetes and Kidney Disease
1 April 2003
Annals of Internal Medicine

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The summary below is from the full report titled "Cardiovascular Outcomes in the Irbesartan Diabetic Nephropathy Trial of Patients with Type 2 Diabetes and Overt Nephropathy." It is in the 1 April 2003 issue of Annals of Internal Medicine (volume 138, pages 542-549). The authors are T. Berl, L.G. Hunsicker, J.B. Lewis, M.A. Pfeffer, J.G. Porush, J.-L. Rouleau, P.L. Drury, E. Esmatjes, D. Hricik, C.R. Parikh, I. Raz, P. Vanhille, T.B. Wiegmann, B.M. Wolfe, F. Locatelli, S.Z. Goldhaber, and E.J. Lewis, for the Collaborative Study Group.


What is the problem and what is known about it so far?
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Diabetes is characterized by persistent elevations in blood sugar. It is one of the most common chronic diseases in the United States and it increases risks for heart disease and stroke (cardiovascular disease). Diabetes often affects the kidneys and causes protein to leak into the urine, a condition called diabetic nephropathy. Many adults with diabetic nephropathy also have high blood pressure. Several different drugs, called antihypertensive agents, can lower blood pressure. Although these agents help prevent cardiovascular disease, we do not know which ones work best in adults with diabetic nephropathy.


Why did the researchers do this particular study?
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To compare effects of an angiotensin-receptor blocker (irbesartan) and a calcium-channel blocker (amlodipine) on cardiovascular disease in adults with diabetic nephropathy.


Who was studied?
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1715 adults with diabetes, nephropathy, and high blood pressure.


How was the study done?
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The researchers randomly assigned patients to begin blood pressure treatment with irbesartan, amlodipine, or a dummy pill (placebo). Neither the patients nor their doctors were told who got which treatment. The researchers often measured each patient's blood pressure. They aimed to lower each person's blood pressure to less than 135/85 mm Hg. Other drugs were added as necessary to control blood pressure. The researchers followed patients for about 2.5 years to see if any patients had strokes or heart disease (heart attacks; heart failure; or coronary artery procedure, such as bypass surgery or stenting).


What did the researchers find?
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Most patients in all three groups needed at least three drugs to control their blood pressure. On average, patients who started treatment with either irbesartan or amlodipine achieved blood pressures of about 140/77 mg Hg. On average, patients who started treatment with the dummy pill achieved blood pressures of about 144/80 mg Hg. Overall, the total numbers of patients with cardiovascular disease did not vary between the three groups. However, patients who started treatment with amlodipine had heart attacks less often than patients who started treatment with the dummy pill. Also, patients who started treatment with irbesartan had heart failure less often than patients in the other two groups.


What were the limitations of the study?
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It was difficult to sort out effects of individual drugs (irbesartan and amlodipine) because most patients needed several drugs for blood pressure control. The researchers also had limited ability to detect differences in numbers of strokes between groups because few patients had strokes.


What are the implications of the study?
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In patients with diabetic nephropathy, starting antihypertensive therapy with either amlodipine or irbesartan has no clear difference in preventing cardiovascular disease.