| Abstract|| |
The increased incidence of the acute kidney injury (AKI) in the elderly is becoming a disturbing reality in our days, mainly with the aging of the general population, and the predisposition of old persons to chronic diseases, drug toxicity, and infections. The aim of this study was to investigate the epidemiological, clinical, and biological features and to assess variant etiologies and outcomes of AKI in the elderly. Data were collected from the medical records of patients older than 65 years age having AKI admitted in the Internal Medicine Department of the Military Hospital of Tunis from January 2006 to June 2014. One hundred and seventeen cases were included in the study. The median age was 74.2 years. Male:female ratio was 1.6. Hypertension and diabetes were the most frequently found comorbidities seen in 69.2% and 48.7% of patients, respectively. The percentage of patients having acute-on-chronic renal failure was 13.7%. The AKI was manifested by nausea or vomiting in 33.3% of cases. One patient had hematemesis. The other symptoms were dyspnea in 14.5% of cases, uremic encephalopathy in 6.8% of cases, and oligoanuria in 16.2% of cases. The AKI was discovered fortuitously in 31.6% of cases and was diagnosed early within the 48 h after admission in 94% of cases and after this delay, in 6% of cases. It was ranked Acute Kidney Injury Network 1, 2, or 3, respectively, in 29.9%, 24.8%, and 45.3% of cases. Organic etiologies were observed more frequently (53.8%) followed by functional etiologies (37.6%) and then by obstructive ones (8.5%). Hemodialysis was performed for 9.4% of the patients. Of all the patients, 70.1% had favorable outcome, 49.6% of patients recovered totally. There was aggravation of the AKI in 29.9% of cases. Death occurred in eight cases (6.8%). The epidemiological, clinical, biological, and etiological profile of AKI in the elderly emphasizes the effect of aging of the human being on determining the pathology.
|How to cite this article:|
Selmi Y, Ariba YB, Labidi J. Epidemiology, diagnosis, and etiology of acute kidney injury in the elderly: A retrospective analysis. Saudi J Kidney Dis Transpl 2019;30:678-85
|How to cite this URL:|
Selmi Y, Ariba YB, Labidi J. Epidemiology, diagnosis, and etiology of acute kidney injury in the elderly: A retrospective analysis. Saudi J Kidney Dis Transpl [serial online] 2019 [cited 2019 Sep 21];30:678-85. Available from: http://www.sjkdt.org/text.asp?2019/30/3/678/261344
| Introduction|| |
Acute renal failure in the elderly is a common disorder whose incidence in the world is increasing owing to aging of the general population, improvement of methods of screening, discovering new biomarkers of acute kidney injury (AKI), concomitant increase of the incidence of chronic kidney disease (CKD), and the use of new diagnostic and therapeutic medical practices that could disturb kidney function.,
However, there are little data on AKI in the elderly. Therefore, it is interesting to know this disease better and refine the methods of screening, prevention, and care.
The aim of this study was to gain insight into epidemiological, clinical, biological, and etio-logical features of AKI and its outcomes in the elderly.
| Patients and Methods|| |
A retrospective descriptive study was performed in the Internal Medicine Department of the Military Hospital of Tunis between January 1, 2006 and June 30, 2014.
All patients older than 65-year-old who had AKI, diagnosed on the classification of the Acute Kidney Injury Network “AKIN” criteria were included.
Data about the epidemiological, clinical, biological, radiological, histological, and etiolo-gical features of the AKI, the therapeutic protocols and the outcome for each patient were collected.
| Results|| |
One hundred and seventeen cases of AKI in subjects aged over 65 years were included. Mean age was 74.2 years and 44.4% of patients were aged over 75 years. A male predominance was observed in our series with a sex ratio of 1.6. Smoking was found in 33.3% of patients and alcoholism in 1.7% of them. The main comorbidities noted were hypertension, diabetes, and urinary tract disease recorded, respectively, in 69.2%, 48.7%, and 22.2% of patients.
The AKI was diagnosed early, within 48 h after admission, in 94% of cases and after this period in 6% of patients. It was classified AKIN stage 1, 2, or 3, respectively in 29.9%, 24.8%, and 45.3% of cases.
The discovery of AKI was fortuitously made in 41% of cases. In the other cases, it was revealed by digestive symptoms with nausea or vomiting in 40 cases and hematemesis in one case, dyspnea in 17 cases, uremic ence-phalopathy in eight cases, and oligoanuria in 19 cases.
Impaired general condition was found in 20.5 of cases. Dehydration was found in 57.2% of patients and an extracellular overhydration in only 9.4% of them. Biologic findings are described in [Table 1].
The AKI was severe in 32 patients. Metabolic acidosis and hyperkalemia were found, respectively, in 16.9% and 17.9% of cases followed by acute pulmonary edema in five cases, gastrointestinal bleeding, and hemodynamic instability in one case each. The origin of AKI was organic in 53.8% of cases, functional in 37.6%, and obstructive in 8.5% of them.
Neurogenic bladder was the most common cause of obstructive AKI (3 cases). Etiology of functional AKI was dominated by dehydration, noted in 50% of cases. Acute interstitial nephritis was the main etiology of organic AKI, affecting 65.1% of cases. It was due to acute pyelonephritis in 23 cases, to sepsis in 12 cases, and multiple myeloma in four cases. Sarcoidosis, tubulointerstitial nephritis, and uveitis syndrome (TINU syndrome) and immune-allergic cause were observed in one case each.
The other etiologies of organic AKI were as follows: acute tubular necrosis in 13 cases (20.6%), acute glomerular nephropathies, and papillary necrosis in three cases each and cortical necrosis in one case. Among acute glomerular nephropathies, one patient had acute glomerulonephritis (AGN) and another one had granulomatosis with polyangiitis. Vascular lesions represented 3.2% of organic causes and were caused by malignant nephron-angiosclerosis. Results concerning AKI etiologies are shown in [Table 2].
Treatment modalities included correction of fluid and electrolyte disorders and interruption of nephrotoxic medication. Vasoactive drugs and diuretics were used in one patient each. Hemodialysis was performed in 9.4% of our patients.
The mean hospital stay was 17 days. The outcome was favorable in 70% of cases, with 49.6% of patients achieving a total recovery and unfavorable in 30% of cases. Death occurred in eight cases (6.8%).
| Discussion|| |
In our study, among the 117 cases, we found that AKI was more frequent in patients with older age and there was a male predominance. Main associated comorbidities were hypertension, diabetes, and urinary tract diseases. AKI was discovered precociously in 94% of cases. It was often asymptomatic. When it was symptomatic, digestive symptoms predominated. It was severe in nearly a third of patients.
Organic etiology was the most frequent, caused mainly by AIN related to infections or systemic disorders, followed by ATN. Functional etiology was due to dehydration in half of cases. The treatment of AKI had two targets: correction of symptomatic disorders and providing etiologic therapeutics with a favorable outcome in major cases.
Diagnosis of AKI always remains difficult to establish because there is no consensual definition. The estimation of glomerular filtration rate (GFR) by using plasma creatinine concentration may be a kinetic means of monitoring the evolution of AKI but should not be considered as the actual GFR because of the influence of nonrenal factors, such as muscle mass, volume of distribution, catabolic state, and medications. This is of particular concern in the elderly patient, in whom reduced muscle mass may induce only a modest elevation in serum creatinine following even severe AKI.,
The risk, injury, failure, loss of kidney function and end-stage kidney disease (RIFLE) and AKIN definitions based on the degree of recovery of urine output and the rise of creatinine concentration are actually only of epidemiological interest. It has been recently identified that age older than 76 years was associated with the failure of RIFLE to accurately predict the outcomes of geriatric AKI patients. The search for specific urinary AKI biomarkers such as neutrophil gelatinase-associated lipocalin, urinary liver-type fatty-acid binding protein, the kidney injury molecule 1, interleukin 18, and cystatin C would move toward early diagnosis. A study published in 2012 showed that cystatin C may be superior to conventional GFR in the diagnosis of AKI in the elderly. The diagnosis of AKI based on the international classification of disease codes is controversial. There is no consensus on diagnosis modalities of AKI in geriatric population.
The greater frequency of AKI among the elderly is explained by both the structural and functional changes in the kidney associated with aging and the impact of many chronic diseases whose incidence increases with age such as diabetes, hypertension and obstructive urinary tract diseases on the kidney, without forgetting the increasing role of iatrogenicity in the geriatric population.
The incidence of AKI is increasing in individuals of all ages. However, people aged over 65 y are more likely to develop AKI. An analysis of Medicare beneficiaries in the USA showed that the incidence of AKI increases from 13.6 episodes in subjects aged between 66 and 69 years to 24.9 for those aged between 75 and 79 years; to 34.2 episodes for those between 80 and 84 and finally to 46.9 episodes for subjects aged over 85 years and this by 1000 patients per year.
Indeed, patients developing AKI are very often elderly persons, a fact that was widely reported in the literature especially in developed countries.,,,
A retrospective study in the United Kingdom on patients in intensive care units found that of 202 patients with AKI collected, 192 (95.1%) were aged over 65 years. Selby et al noted that the median age of patients with AKI was 80 years.
However unlike the western populations, the AKI, in countries of Africa and India, is characterized by its occurrence in younger subjects with a mean age of around 40 years and this can be explained by the low life expectancy in these countries.,,,,,
In our study, the mean age of patients was 74.22 years, ranging from 65 to 92 years. An age greater than or equal to 75 years was noted in 44.4% of the patients.
There was a male predominance in elderly patients with AKI. This has been confirmed by several studies.,,, In fact, it has been proven experimentally and clinically that the female sex hormones have a protective role on the kidneys through a lesser stimulation of renin-angiotensin-aldosterone system, an increase of the rate of oxyde nitrogen and metallo-proteases.,,,,,,,, In our series, the sex ratio was 1.6; a result that is consistent with most published series.
In the literature, most of the elderly patients with AKI have a history of hypertension, diabetes, preexisting chronic renal failure, or cardiovascular disease. In our work, hypertension was noted in 69.2% of patients and diabetes in 48.7% according to the large cohort study of Mittalhenkle. However, Druml has reported lower percentages, respectively, 29% and 15%. The association between diabetes and hypertension and AKI may partially be mediated through the pathway of early CKD, because CKD likely predisposes to AKI. CKD was found in 13.7% of our patients against 30% in the study of Mittalhenkle. This may be due to the lack of screening for CKD in our country. According to the literature, we found a high frequency of associated cardiac pathology.
In our study, clinical manifestations were dominated by general extra-renal signs like impaired general condition in 20.5% of cases and digestive symptoms in 33.3% of cases. Oliguria and anuria were observed, respectively, in 12% and 6% of cases, which is less frequent that in the most previous data.,,,
According to Cameron, AKI can be a revelation mode of nephrotic syndrome (NS) in the elderly, in whom it is often misdiag-nosed with a heart failure particularly among patients with minimal glomerular lesion or glomerular sclerosis.
Gong et al did not find any significant differences between the biological data of young and old patients.
Since the practice of renal biopsy is not common in the elderly because of the frequency of the presence of contraindications, the etiologic diagnosis of AKI is often presumptive, based on clinical criteria. The causes of AKI in the elderly and adults differ in their distribution. In the elderly, the two most common mechanisms are absolute or relative hypovolemia causing functional renal impairment and second, urinary tract obstruction.
In contrast with studies from western countries, the etiologies of AKI in our study were obstructive in 8.5% of cases, functional in 37.6% and organic in 53.8%. This may be explained by the frequency of the infectious etiology in our country responsible for a large part of septic AIN.
Obstructive AKI has an increasing incidence in the elderly population because of the high incidence of prostatic pathology and pelvic tumors. In our study, it was observed in 10 patients who represented 8.5% of the population. Prostatic hyperplasia affects 50% of men over 50 years old and 90% of men over 90 years old.
The main causes of obstructive AKI include prostate adenoma, prostate cancer, cervical uterine tumors, and retroperitoneal pathologies.,
Prerenal or ischemic AKI is responsible for the largest proportion of AKI in the elderly. However, some studies found a less important part of this functional origin, especially in the very elderly patients., According to various authors, dehydration represents the main cause of functional AKI. Its frequency ranges from 38.3% to 74.4% in functional AKI and from 21.7% to 27.9% in overall AKI.,,,
In our study, dehydration accounted for 64% of functional AKI and 20% of total AKI cases, joining both international and national studies results.
Drugs are a significant cause of functional AKI as reported by Tsagalis. It was mainly nonsteroid anti-inflammatory drugs (NSAIDs) and to a lesser extent anti-cox-2 agents, contrast agents, cisplatin, ciclosporin, angiotensin-converting enzyme inhibitors (ACEIs), sartans.
A 2005 UK comparative study found that short-term and long-term use of NSAIDs in patients with diabetes, heart failure taking diuretics, or calcium channel blockers or who were hospitalized in the previous year is associated with increased risk of AKI (3-to 4fold higher) while taking ACEIs was not significantly associated with an increased risk of AKI.
In our study, drugs found to be responsible for functional AKI were ACEIs and/or angio-tensin receptor blockers (ARBs) in 8% of cases.
Organic AKI is, according to several authors, the most common cause of AKI., Its frequency varies from 44.4% to 68.5% of total AKI. In our study, its frequency reaches 53.8%. AIN was the most common etiology; about 65% of organic AKI cases and 35% of the study population, probably due to the frequency of infectious etiology, especially in the fragile, elderly population.
In the literature data, it is suggested by various studies that ATN is the most common cause of AKI in the elderly. While sepsis and ischemia are the two main mechanisms of ATN in adults without nephropathy, we must underline the high frequency of drug-induced or contrast agent-induced ATN in the elderly.,
AGN account for one-third of parenchymal causes of AKI in the elderly, compared with less than 10% in young subjects. A recent study published in 2010 by de Oliveira et al including 71 renal biopsies performed in patients over 60 years showed that renal biopsy was indicated for AKI in 19 cases and the main histopathological diagnosis was ATN (six cases) followed by myeloma nephropathy (three cases).
Treatment of AKI is first of all preventive. In fact, particular care should be given to patients at risk, particularly elderly patients with vascular, heart, or hepatic disease., It must be verified that drugs that can interfere with renal hemodynamics have been stopped and that drug doses are adapted to the renal function. X-ray examinations must be performed without contrast agents and, in case of absolute indication, the least osmolar product, and the smallest amount needed must be used with the implementation of all necessary preventive measures (stopping diuretics, NSAIDs, ACEIs, ARBs rehydration…). Treatment of organic AKI has no specificity, apart from cortisone sparing in glomerular causes.
The prevalence of AKI requiring extra-renal treatment is 5%–6%. In our study, 9.4% of the patients underwent extra-renal treatment. Extra-renal treatment remains a discussed choice of treatment in elderly population. In the general population, extra-renal treatment in AKI increases the risk of renal damage leading to chronic renal failure and sometimes to the need for permanent dialysis., However, some believe that age should not be a contraindication to initiate an intensive therapy, including initiation of extra-renal treatment., The therapeutic strategy must be made case-by-case, depending on patient condition and the underlying pathologies.
| Conclusions|| |
In summary, we conclude that AKI in the elderly is certainly a common but often potentially treatable disease because of the frequency of functional and iatrogenic etiologies. From this, it is clear to see the importance of improving the means of detection of AKI, especially with the advent of new AKI biomarkers. The indications for renal biopsy should also be expanded in this population.
Further studies need to be performed to assess epidemiological, clinical, paraclinical features of AKI in this particular population and to describe its modalities of progress and to identify the factors of poor outcomes.
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Yosra Ben Ariba
Department of Internal Medicine, Military Hospital of Tunis, Tunis
[Table 1], [Table 2]