Lawrence J. Appel, MD, MPH, is the director of the Welch Center for Prevention, Epidemiology, and Clinical Research at Johns Hopkins University. His clinical research focuses on preventing blood pressure-related cardiovascular and kidney diseases. Here, he discusses the link between high blood pressure and kidney disease, and the importance of early detection and management.

Q: What is the link between kidney disease and high blood pressure?

A: High blood pressure is a leading cause for many adverse conditions, such as stroke, heart disease, heart failure, and possibly cognitive decline. Many patients are unaware of the link between elevated blood pressure and kidney disease.

In the United States, high blood pressure affects 108 million people, or almost 1 in 2 adults. High blood pressure is a condition that develops over time and requires long-term treatment to manage effectively. High blood pressure is the second leading cause of kidney failure in the United States. Kidney disease is one of the main outcomes of having high blood pressure over a period of years.

By middle and older ages, many individuals start to develop high blood pressure, requiring treatment. By age 50, 60, or 70, a lot of people have high blood pressure.

Q: What are your key messages about kidney disease for health care professionals who have patients with high blood pressure?

A: Perhaps the most important message is to keep patients under care. A lot of patients miss follow-up visits or even drop out of care. Without routine care, patients run out of medications, so that diabetes and high blood pressure become uncontrolled, leading to faster progression of kidney disease.

Second, while drug therapy is a mainstay, especially for blood pressure control and controlling diabetes, don’t underestimate the benefits of lifestyle changes for patients.

Third, measure blood pressure accurately. Health care providers and their assistants should follow the recommendations of the Journal of American College of Cardiology Scientific Expert Panel to measure blood pressure in a medical setting with the patient seated, resting quietly with their back supported and feet flat on the floor. Use of validated automated devices reduces much, but not all, of the error associated with manual devices, like aneroid manometers.

Fourth, encourage patients with diabetes to monitor their blood pressure and blood sugar. Provide training so that patient readings are accurate. This type of physician-patient partnership can make patients happier, more satisfied, and want to continue with their care.

Q: What's the relationship between chronic kidney disease and diabetic kidney disease?

A: Chronic kidney disease occurs when kidney function has deteriorated, but the term doesn't specify the actual cause of the kidney disease. It could be related to diabetes, hypertension, or certain genetic conditions like polycystic kidney disease. Diabetic kidney disease is a form of chronic kidney disease in which diabetes appears to be the cause.

Most people who have diabetes, especially type 2 diabetes, have hypertension as well. When a patient has both kidney disease and diabetes, they often have hypertension.

Q: What factors should health care professionals be aware of that can place patients at a high risk for high blood pressure, kidney disease, and diabetic kidney disease?

A: Age is probably the most important risk factor for all of these conditions. As people age, the risk of high blood pressure, diabetes, and kidney disease, including diabetic kidney disease, increases.

Race and ethnicity are also factors. African Americans have a very high risk of kidney disease, some of which may be related to having the APOL1 gene. However, even African Americans without the gene are at higher risk of developing kidney disease. American Indians are also at higher risk of kidney disease, but the actual risk level may differ between specific tribes. Certain tribes have a higher risk of kidney disease than others. Hispanics/Latinos also show a higher rate of kidney disease compared to non-Hispanic whites. Many of the differences in kidney disease by race and ethnicity are related to health and health care factors, such as poverty or access to care, as opposed to being directly related to race or ethnicity.

As mentioned previously, as blood pressure rises, so does the risk of chronic kidney disease and diabetic kidney disease.

Poor glycemic control and duration of diabetes increase the risks of developing diabetic kidney disease and other complications of diabetes.

Other factors associated with increased risk of developing high blood pressure and chronic kidney disease and/or diabetic kidney disease include

• Quality health care. Lack of health care continuity greatly affects the progression of these conditions.
• Food and beverages. What we eat and drink can directly affect blood pressure and glucose control in people with diabetes.
• Geographic location. The geographic distribution in the United States of high blood pressure, chronic kidney disease, diabetes, and obesity, while not completely overlapping, is highest in the southeastern states, from Virginia through Louisiana. Non-African Americans living in this area also show high rates of these conditions.
• Lower socioeconomic status. Individuals who are poor have a high risk of developing kidney disease. Less access to health care might be one reason.

Q: What can health care professionals do to help patients with high blood pressure prevent or slow the progression of kidney disease or diabetic kidney disease?

A: Health care professionals should measure patients’ blood pressure often and correctly. They should use a combination of lifestyle changes (for all patients) and medications (for some patients) to help patients achieve a target blood pressure less than 130/80 mm Hg.

Lifestyle changes include being physically active, except for those who are severely ill. Patients should quit smoking, which benefits them and their friends and family. Patients should strive to maintain a healthy weight by choosing healthier food and beverages. Heart-healthy eating plans, such as the Dietary Approaches to Stop Hypertension (DASH) eating plan, are especially important for people with high blood pressure. The DASH eating plan is rich in fruits, vegetables, and low-fat dairy, and includes reduced amounts of saturated fats, cholesterol, and sodium. Managing stress can also help patients achieve the other lifestyle changes.

Medications have an important role in controlling blood pressure and preventing the complications of high blood pressure. These medications include angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), calcium channel blockers, and diuretics.

All patients should have regular laboratory testing (glomerular filtration rate (GFR) and urine testing) to monitor the progression of their kidney disease. As kidney disease advances, monitoring frequency may increase, as well as the need for other checks such as blood levels of potassium. Patients with diabetic kidney disease should have their A1C glucose levels checked regularly to ensure they meet their target levels.

When somebody starts getting kidney disease, they really need to be under routine medical care. Most patients will be under the care of a primary care provider. We just don't have enough nephrologists to manage all the people with early stages of kidney disease. Patients are going to be seen by family physicians, internists, physician assistants, and nurse practitioners. They're the people who are on the front lines, especially for patients with early stages of kidney disease and for people with diabetes. Health professionals should also monitor people with diabetes for other comorbidities, including eye disease, peripheral artery disease, and heart and kidney diseases.