Older Americans with high blood pressure and moderate to severe chronic kidney disease have a greater chance of developing heart disease than people with normal kidney function. This finding is one of three in a new paper published in the Feb. 7 issue of the Annals of Internal Medicine.
The study also found these patients are at higher risk for developing heart disease than kidney failure (end stage renal disease). Lastly, it found for the first time that new types of drugs such as ACE inhibitors and calcium-channel blockers are no better than older type diuretic drugs, also called water pills, in preventing heart disease, and may be even less effective at preventing heart failure in patients with chronic kidney disease.
Lead author of the study is Mahboob Rahman, M.D., M.S., of Case Western Reserve University School of Medicine, University Hospitals of Cleveland and the Louis Stokes Cleveland VA Medical Center. The study was sponsored by the National Heart Lung and Blood Institute and coordinated by the Clinical Trials Center at the University of Texas School of Public Health in Houston.
The study looked at more than 31,000 men and women 55 years and older who have high blood pressure and one other risk factor of cardiovascular disease, such as diabetes. A blood test was used to determine kidney function and severity of disease.
Patients with moderate chronic kidney disease had a 38 percent greater chance of developing heart disease and a 35 percent increase in overall cardiovascular disease (which includes heart disease, stroke, heart failure and others) than those with normal kidney function. In addition, patients with moderate to severe chronic kidney disease were twice as likely to develop heart disease than to experience kidney failure.
Rahman said the researchers are not quite sure why moderate and severe kidney disease leads to greater risk in heart disease. "It may be related to other factors associated with renal failure, such as anemia or abnormalities of calcium or phosphorus metabolism, for example. We are participating in other ongoing studies to establish the connections," he said.
The study also confirmed other earlier findings that diuretics are as effective as or better for preventing cardiovascular disease than newer drugs.
"Overall, ACE inhibitors and diuretics were about equally likely to protect against heart attacks," said Rahman, "but diuretics seemed more effective at preventing other kinds of cardiovascular diseases, such as stroke and heart failure."
Calcium-channel blockers were about equal in protecting against all cardiovascular disease, but diuretics were more effective at preventing heart failure. These results held for all participants regardless of kidney function.
Rahman cautioned patients not to stop taking their medications after reading these results, however, and to consult their physicians.
He added, "Exercise, maintaining optimal body weight, smoking avoidance, and maintaining low cholesterol levels - these are all things that should be done with renewed emphasis in most patients with high blood pressure. Most patient with hypertension and chronic kidney disease will require multiple medications to control blood pressure. Our results demonstrate that the risk for cardiovascular disease is lower if one of the medications is a diuretic."
He recommends patients who have high blood pressure talk to their doctors about measuring their kidney function to determine if they are suffering from chronic kidney disease.