The Importance of Early Screening for Chronic Kidney Disease

Chronic Kidney Disease (CKD) is a global health concern, and late diagnosis can lead to severe complications. Medical societies worldwide are now advocating for early screening to curb the progression of the disease. Virtually all patients in primary healthcare settings might be potential candidates for screening due to various risk factors associated with kidney disease.

Unpacking the Case for Early Screening

During the 29th National Conference of General and Family Medicine of the Spanish Society for General and Family Physicians (SEMG), esteemed medical professionals presented a compelling case for the significance of early screening for CKD.

Understanding Risk Factors

Teresa Benedito, MD, a family doctor, and Roberto Alcázar, MD, a nephrologist, outlined the risk factors for kidney disease. These include:

• Age over 60
• Family history of CKD
• Decreased kidney mass
• Hypertension
• Diabetes
• Smoking
• Obesity
• Low socioeconomic status

Dr. Alcázar emphasized that these factors mirror cardiovascular risk factors, stating, “The kidneys are a ball of vessels with double capillarization for purifying blood. They’re the organs with the most arteries per unit of weight, so anything that can damage the arteries can damage the kidneys.”

The Need for Wider Screening

CKD affects approximately 15% of the adult population in Spain, leading to questions about who should be screened. Dr. Alcázar added that patients on nephrotoxic drugs or those with a history of acute kidney injury due to chronic autoimmune disease or neoplasms should also be considered for screening. Therefore, almost all patients seen in primary care could potentially benefit from kidney disease screening.

The Two Pillars of Chronic Kidney Disease Screening

Screening for chronic kidney disease pivots on two critical parameters: glomerular filtration rate and albuminuria. Dr. Benedito emphasizes their significance, stating that these factors form the foundation for CKD screening.

Glomerular Filtration Rate

The glomerular filtration rate fluctuates based on factors such as:

• Age
• Sex
• Ethnicity
• Body mass

This parameter serves a dual purpose:

• Pinpointing the stage of the disease
• Tracking disease progression

Albuminuria

Albuminuria is another crucial metric, serving as:

• An indicator of the disease’s severity
• An early warning sign for kidney injury and systemic disease

Compared to proteinuria, albuminuria is more sensitive, making it a reliable marker for early detection.

The Symbiotic Relationship of the Two Parameters

Together, the glomerular filtration rate and albuminuria enable healthcare professionals to:

• Detect CKD early
• Classify the disease stage
• Monitor disease progression over time

Dr. Alcázar underscores the importance of observing trends in these parameters, given that the glomerular filtration rate can vary by nearly 9%, depending on serum creatinine levels. He further explains that a glomerular filtration rate of less than 60 mL/min indicates the loss of more than half of the nephrons in each kidney, while albuminuria provides insights into the structural damage of the remaining nephrons.

Addressing the Trend of Late Chronic Kidney Disease Diagnosis

The IBERICAN study reveals a concerning statistic: 14% of patients in primary care in Spain are living with chronic kidney disease (CKD). This alarming figure is a wake-up call for healthcare professionals, urging them to reevaluate current screening practices.

Dr. Benedito underscores the need to:

• Reflect on this statistic and its implications
• Acknowledge our responsibility in early CKD detection
• Question why earlier screening isn’t more prevalent

She advocates for an urgent reversal of the current trend of late diagnosis. As CKD advances, it considerably raises cardiovascular risk, increases mortality rates, and often necessitates dialysis or transplants.

Echoing these sentiments, Dr. Alcázar points out that a significant 80% of nephrology cases he encounters originate from primary care. He emphasizes the gravity of the situation, explaining that these patients face a sevenfold higher risk of experiencing a severe cardiovascular event within the next year compared to those without kidney issues. Alarmingly, most of these patients might experience such an event even if they don’t require dialysis (those in stage 3 and nearing stage 4).

These observations underline the pressing need to curb late CKD diagnosis. By implementing earlier and more routine screening, we can significantly improve.

Staging Chronic Kidney Disease

Understanding the staging of chronic kidney disease is crucial for effective management. Dr. Benedito emphasizes the importance of using a chart that pairs glomerular filtration rate (across six categories) with albuminuria levels (across three categories) during patient consultations. This chart can help classify cases, such as G3a-A2, for instance.

However, a simplified version of this chart may prove more practical in some scenarios. This version categorizes chronic kidney disease into mild, moderate, and severe risk levels, using different colors for easier comprehension.

Recognizing Albuminuria’s Role

Dr. Alcázar highlights that the European Society of Hypertension’s latest guidelines for 2023 recognize albuminuria as a significant parameter. The guidelines suggest that for patients at moderate or severe risk, calculating their score isn’t necessary. These patients are already considered at high cardiovascular risk, necessitating immediate intervention.

Tools for Reversing Albuminuria

There are several strategies available to reverse albuminuria, starting with reducing salt intake. These include:

1. Use of medications such as:

• Angiotensin-converting enzyme inhibitors
• Angiotensin II receptor antagonists
• Aldosterone receptor antagonists
• Glucagon-like peptide-1 analogues
• Sodium-glucose cotransporter-2 inhibitors (which slow kidney damage regardless of other measures)

2. Strict management of cardiovascular risk factors including:

• Smoking cessation
• Weight management
• Blood glucose control
• Hypertension control
• Regular moderate physical activity

Reducing Cardiovascular Risk

Dr. Alcázar underscores the importance of effectively managing cardiovascular risk factors in patients with chronic kidney disease.

Managing Hypertension

For hypertension, the target is to maintain levels below 130/80 mm Hg, although this can vary based on different guidelines. The 2021 KDIGO (Kidney Disease: Improving Global Outcomes) guidelines suggest focusing on systolic blood pressure (SBP) rather than diastolic blood pressure. If measured according to standardized methods, SBP should be less than 120 mm Hg. If not, the fallback readings should be 130/80 mm Hg.

Controlling Lipid Levels

For lipid control, particularly low-density lipoprotein cholesterol, the targets based on the staging chart are as follows:

• Mild risk: Levels should be below 100 mg/dL
• Moderate risk: Levels should be below 70 mg/dL
• Severe risk: Levels should be below 55 mg/dL

Hypertriglyceridemia should only be treated with fibrates if levels exceed 1000 mg/dL. However, caution is needed as these drugs can interfere with creatinine excretion, causing an increase in its levels.

Managing Diabetes

The KDIGO and American Diabetes Association guidelines recommend that anyone with diabetes and chronic kidney disease should receive a sodium-glucose cotransporter-2 inhibitor if their glomerular filtration rate is above 20 mL/min. This recommendation might slightly contradict what’s mentioned on the label. Additionally, if these patients have hypertension, they should also take an angiotensin-converting enzyme inhibitor.

Dr. Alcázar further notes that “oral antidiabetics, including metformin, must be adjusted based on renal function if the glomerular filtration rate is under 30 mL/min.”

The Urgency of Immediate Action in CKD Management

Dr. Alcázar asserts that the progression of chronic kidney disease (CKD) can indeed be altered, and associated cardiovascular risk can be significantly reduced.

According to him, nephrologists often lack access to patients in the early stages of CKD, whereas family doctors do. This fact underscores the critical importance of:

• Early screening for CKD
• Recognizing that starting dialysis at age 60 has different implications than starting at age 80
• Noting that scientific societies are currently urging authorities to begin CKD screening at younger ages

Drug-Based Therapy and Recent Studies

When it comes to medication, Dr. Alcázar mentions that empagliflozin, a sodium-glucose cotransporter-2 inhibitor, is not currently indicated for adult CKD. However, this drug delays kidney disease progression and reduces morbidity, as highlighted in two recent studies, DAPA-CKD and CREDENCE.

The EMPA-KIDNEY study, published in January, introduced a novel approach to nephroprotection for patients with CKD (whether diabetic or not). It focuses on patients with glomerular filtration rates between 20 and 40 mL/min without albuminuria or those with rates between 45 and 90 mL/min with albuminuria.

For over 6000 patients, empagliflozin showed promising results:

• A clear reduction in kidney disease progression
• Decreased cardiovascular mortality
• Lowered all-cause mortality
• Reduced need for dialysis

The push for early screening for CKD is gaining momentum globally. With the right approach to identification, diagnosis, and management, we can significantly reduce the impact of this disease. Primary care physicians play a key role in this process, making early detection and effective treatment a reality for more patients.