Analysis: the development of kidney disease in Ireland's health system is linked to the 126% increase over a decade in Acute Kidney Injury amongst Irish patients
Chronic Kidney Disease (CKD) is a common chronic condition that affects 15 percent of adults in the Irish health system and has a major impact on a person's health. The term CKD reflects permanent kidney damage and is defined clinically as a reduction in kidney function (typically less than 60 percent of normal function) or a leaking of protein through the kidneys (called proteinuria). CKD can lead to kidney failure, for which a patient may require dialysis or kidney transplant, and substantially shortened lifespan
In Ireland, over 4,440 individuals were receiving treatment for kidney failure at the end of 2017 (54 percent with a kidney transplant and the remainder on dialysis), and the numbers have been increasing year on year. Each year, over 400 new patients develop kidney failure and require dialysis, a rate of 90 per million head of population. In fact in over a decade, the numbers of patients who develop kidney failure in Ireland has increased from 2,848 in 2005 to 4,440 in 2017 (a growth of 56 percent).
CKD may results from several causes including diabetes, high blood pressure, polycystic kidney disease and other specific diseases of the kidney. However, there is a growing body of evidence that Acute Kidney Injury (AKI) may also be responsible for kidney failure in some cases and may accelerate the progression of CKD in many others.
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From RTÉ Radio One's Today With Sean O'Rourke Show, Dr. Colm Magee, Consultant Nephrologist and Transplant Physician in Beaumont Hospital, talks about the paired kidney transplant program
What is Acute Kidney Injury (AKI)?
Acute Kidney Injury was formerly called acute renal failure and describes the sudden and often temporary loss of kidney function that can occur when the kidney is suddenly damaged. There are many causes for this, ranging from severe dehydration, acute illnesses like pneumonia, specific medications like anti-inflammatory drugs or dyes that are used to outline the coronary arteries when doing an angiogram. Some patients are more prone to AKI than others, especially the elderly, patients with pre-existing kidney disease, diabetes and dehydration, and patients who are treated with multiple medications. AKI is silent and most patients may not even realise that their kidneys are affected unless a blood test called the serum creatinine is measured.
Severity of AKI
AKI can range in severity from mild (graded as Stage 1) to severe (graded as Stage 3), where severe forms are more likely to cause kidney failure and require dialysis. Many times, this is reversible but depending on the cause and severity, it may be irreversible and lead to chronic kidney disease and kidney failure and death.
Why is AKI important?
There is a growing body of evidence that links AKI with the development of chronic kidney disease (CKD). When a patient suffers an acute AKI event, the outcome is one of the following: full recovery of kidney function, partial recovery of kidney function and, for a small minority, the kidney never recovers and the patient developed immediate kidney failure.
While recovery of kidney function occurs in the majority of patients who survive an AKI episode, it has emerged that a large number of patients do not recover their kidney function completely and are left with chronic kidney damage (CKD). There is increasing proof that every episode of AKI is linked to a greater risk of kidney failure. The more severe the AKI, the greater the risk.
Our research
Given the emerging importance of AKI as a risk factor for kidney failure, we wanted to find out how common AKI was in the Irish health system and whether the frequency of AKI episodes has changed over time. We used information from the National Kidney Disease Surveillance System (based in UL’s Graduate Entry Medical School) to track trends in the rates of AKI from 2005 to 2014.
The National Kidney Disease Surveillance System is designed to identify all patients over 18 years of age with kidney disease within the health system using routine makers of kidney disease that are commonly screened for in primary care or hospital settings. The system links health information from several sources including regional laboratory information systems (which capture all inpatient and outpatient laboratory tests within a designated region), dialysis registers that capture patients who progress to kidney failure and information on deaths that were available from the national Central Statistics Office (CSO).
We found that the overall rate of Acute Kidney Injury increased from 5.5 percent to 12.4 percent over the nine year period (a growth of 126 percent).
How big was the study?
The entire study allowed us to track the clinical course of 451, 646 patients in the Irish health system from 2005 to 2014.
What did we find?
(1) During this period, we identified 40,786 episodes of AKI. We found that the overall rate of AKI increased from 5.5 percent to 12.4 percent over the nine year period (a growth of 126 percent). In 2014, more than 12 percent, or one in eight patients in Ireland, experienced an acute insult to their kidneys leading to a rapid reduction in kidney function.
(2) Patients who suffered an AKI event were generally older in age, male, hospitalised as inpatients or located in the emergency department, and had higher levels of inflammatory makers and poorer nutrition.
(3) Among all AKI episodes, Stage 1 occurred most frequently (81.3 percent), followed by Stage 2 (11.6 percent) and Stage 3 (7.1 percent). From 2005 to 2014, the rate of AKI Stage 1 (mild) increased from 4.4 percent to 10.1 percent (a 130 percent increase), while Stage 3 AKI (the most severe form of AKI) increased from 0.46 percent to 0.81 percent (a 76 percent increase).
Men were 28 percent more likely to experience an Actute Kidney Injury event than women
(4) Men experienced higher rates of AKI than women and this persisted over the nine year period.
(5) A trend of rising rates of AKI was observed in most clinical settings such a emergency departments, inpatient wards, outpatient clinics and general practice. The highest rates of AKI were detected among hospitalised patients where the rates increased from 28.8 percent in 2005 to 46.2 percent in 2014.
(6) We also found variation in rates of AKI across counties
What factors were related to the increase in rates of AKI over time?
(1) Older patients were more likely to experience an AKI event over time (25 percent risk for every five year increase in age)
(2) Men were 28 percent more likely to experience an AKI event than women
(3) Inpatients were 19 times more likely to experience an AKI event than patients in general practice, while patients in the emergency department were almost six times more likely to have an AKI than those in general practice
Patients who entered the health system in 2014 were at least 4.4 times more likely to experience an AKI event compared to those in 2005
(4) Patients with a Clare, Limerick or Sligo address were far more likely to experience an AKI event than those in Donegal accounting for differences in age, sex, and location of medical supervision.
(5) Patients who entered the health system in 2014 were far more likely (at least 4.4 times more likely) to experience an AKI event compared to those in 2005, taking into consideration changes in age, sex, country of origin, baseline level of kidney function, and indicators of health illness. This would suggest that these factors (age, sex, county of residence, patients health status) do not explain the rapid increase in AKI rates over the nine year period and suggest that other factors might be responsible.
What does this study mean for patients?
(1) AKI is very common among Irish patients who enter the Irish health system and puts patients at greater risk of death and kidney failure
(2) The highest risk groups were elderly, men, patients hospitalised as inpatients, attending emergency departments and outpatient clinics, and those with poorest kidney function.
(3) Stage 1 (mild) is the most common form of AKI and is far more common than Stage 2 and Stage 3 AKI (severe forms)
We have revealed a huge increase in the rate of AKI in the Irish health system and this is a cause for concern
(4) Despite the alarming rise in rates, there was evidence that the overall growth of AKI overall appears to have plateaued in recent years and that the most severe form of AKI (stage 3) had declined in frequency from 2012 to 2014 (from 0.80 in 2012 to 0.71 in 2014)
(5) We need to develop better systems of management for the prevention and treatment of AKI, and track the quality of these interventions prospectively
What does this study mean for the Irish health system?
We have revealed a huge increase in the rate of AKI in the Irish health system and this is a cause for concern. Prior studies have shown that AKI is common affecting about 20 percent of hospitalised patients and is harmful leading to death and disability. AKI is a silent condition that can cause significant harm to people, lead to kidney failure and reduce life expectancy.
The Irish health system needs to respond with an appropriate multi-pronged cross disciplinary approach. Key strategies to prevent AKI and its consequences include:
(1) Education and awareness of AKI: the first step is to recognise that we have a problem across the health system and we have shown this in this large study. Key strategies to prevent AKI and its consequences include: greater public and physician awareness
(2) Early identification of high-risk individuals: elderly, diabetes, acute illness, patients undergoing surgery or receiving contrast for radiology procedures.
(3) Early detection of AKI in all clinical settings using specific criteria and electronic alert systems,
(4) Early use of treatment strategies including prevention of dehydration, avoidance of nephrotoxic medications (drugs that damage kidneys),
(5) Early referral/discussion to kidney specialists.
(6) We would advocate for the development and implementation of a national strategy designed to prevent the occurrence of Acute Kidney Injury and its consequences in the health system.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
