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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Almost 1 in 2 people with chronic kidney disease are undiagnosed, research found. Many are therefore not receiving recommended treatment, such as medicines to lower blood pressure (antihypertensives). This puts them at risk of their kidney disease getting worse, and of other conditions such as heart failure.

High blood pressure can cause chronic kidney disease and drive its progression. Current guidelines recommend that people with chronic kidney disease take antihypertensives, and medicines (such as statins) to lower cholesterol levels, even if their cholesterol levels are normal.

Researchers carried out a study in Lambeth, an ethnically diverse area of South London. They aimed to find out how many people with moderate to advanced chronic kidney disease (stage 3-5) go undiagnosed. They explored whether people with the disease receive appropriate treatment, and which groups are most at risk of being under-treated.

Targets for controlling high blood pressure were often not met in people with chronic kidney disease, the study found. Those least likely to achieve recommended blood pressure levels included people over 60 years, of Black African ethnicity, and those with obesity.

The research emphasises the importance of screening, recording and treating high blood pressure and cholesterol levels in these vulnerable groups. This would prevent future kidney disease and cardiovascular disease, the research team says.

Further information on kidney disease is available on the NHS website.

What’s the issue?

Estimates suggest that in England, around 6% people – 3 million in all - have chronic kidney disease. Many do not realise they have the condition because it has few symptoms in the early stages. Sometimes there are no symptoms at all. This can mean people do not receive advice and treatment to prevent it getting worse.

In around 1 in 1000 people, the kidneys stop working (kidney failure). These people need a kidney transplant or regular dialysis, which takes over some of the kidney’s functions.

Chronic kidney disease is more common when people have other conditions that put a strain on the kidneys (such as high blood pressure). These conditions also make chronic kidney disease worse. Controlling high blood pressure with antihypertensives can help slow the progression of chronic kidney disease.

Researchers wanted to find out how well chronic kidney disease is diagnosed and treated, and which groups of people are most likely not to receive recommended treatment.

What’s new?

The researchers gathered anonymised data from 286,000 patient records from 47 GP surgeries in Lambeth. This included 4,131 people with moderate to advanced chronic kidney disease (stage 3-5). The study did not include people with diabetes, who can have different risk factors for kidney disease.

The 4,131 people with kidney disease were identified through recorded blood tests. But for many, their records were not flagged. They might not have known they had kidney disease.

On diagnoses, the study found that:

  • almost half (48%) of those with chronic kidney disease stage 3-5 were undiagnosed.
  • half (50%) of those with chronic kidney disease (both diagnosed and undiagnosed) had also been diagnosed with high blood pressure.
  • almost 1 in 4 (23%) people with undiagnosed chronic kidney disease also had undiagnosed high blood pressure.

The researchers looked at people's prescriptions, to see how well blood pressure, cholesterol and other health conditions, were being managed.

On treatments, the study found that:

  • medicines to lower cholesterol were under-prescribed, especially for people under 75; they were prescribed in less than half of those with moderate (stage 3-4) chronic kidney disease
  • in people with high blood pressure and chronic kidney disease:
    • 1 in 15 (7%) were not taking antihypertensives
    • of those taking antihypertensives, only 2 in 3 (64%) had controlled blood pressure.

The researchers looked at different groups of people and found that:

  • those under 60, or diagnosed with chronic kidney disease, cardiovascular disease, or serious mental illness were likely to have better blood pressure control.
  • those over 60, of Black African ethnicity, or living with obesity, were likely to have poorer blood pressure control.
  • those under 75, of Black African, Asian or Other ethnicity, were most likely to have undiagnosed stage 3 chronic kidney disease.

Why is this important?

People with undiagnosed chronic kidney disease are usually not aware of the severity of their condition. Primary care professionals need to be more aware of the importance of managing risk factors. This includes treatment of blood pressure and cholesterol, smoking cessation and obesity guidance. These measures prevent the development and progression of chronic kidney disease.

Public health strategies and education about chronic kidney disease can help reduce related illness and early deaths. Ensuring that kidney disease is recorded and flagged in people's medical notes will improve the data standards, and patient care.

This study offers insights into health inequalities in people aged 60 years and older, those of Black African ethnicity, and those who have obesity. These groups are at increased risk of kidney disease that progresses, and of cardiovascular disease. Diagnosis of chronic kidney disease needs to be improved in people under 75, of Black African, Asian and Other ethnic groups.

What’s next?

The team calls for improvements to flagging (coding) of chronic kidney disease in electronic medical records. This would help GPs identify people with chronic kidney disease and support better care. The researchers would like to see increased prescribing of antihypertensives and medicines to lower cholesterol.

In further studies, the researchers are trialling a home test to detect protein in urine. They are exploring use of the test (a postal testing kit and a smartphone app) in people with high blood pressure, diabetes and other long-term conditions. The aim is to diagnose kidney diease earlier, and help people access treatment sooner.

The study was carried out in London. Further research in other regions could establish whether these findings are true elsewhere.

You may be interested to read

The NIHR Alert was based on: Carpio EM, and others. Hypertension and cardiovascular risk factor management in a multi-ethnic cohort of adults with CKD: a cross sectional study in general practice. Journal of Nephrology 2022;35:901–910

National Institute for Health and Care Excellence (NICE). Chronic kidney disease: assessment and management. NICE guideline [NG203]. 2021

Information for patients on chronic kidney disease from Kidney Research UK.

Funding: This research was supported by the NIHR Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust and King's College London.

Conflicts of Interest: None declared.

Disclaimer: Summaries on NIHR Evidence are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that the views expressed are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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