Abstract
Objective: We aimed to evaluate acute kidney injury (AKI), occurrence of recovery and risk factors associated with permanent kidney injury and mortality in the elderly individuals. Design: Evidence for this study was obtained from retrospective cohort study from our center. Patients: A total of 193 patients (>65 years, mean age: 79.99 ± 6.93) with acute kidney injury were enrolled in this study between 2011 and 2012. Patients with kidney failure or renal replacement therapy (RRT) history at admission were excluded. Intervention: Main outcome measurements: serum creatinine (SCr), estimated GFR (with CKD-Epi) and complete blood counts were evaluated at baseline and daily basis thereafter. The AKI was defined based on Kidney Disease Improving Global Outcomes (KDIGO) classification. Results: Among 193 patients, 43 (22%) patients required RRT. Mortality rate was 18% (n = 36) SCr levels were restored within 9.9 ± 6.7days on average (8–39 days). Sixteen patients (12.7%) required RRT after discharge. The mean hospital stay was 10.1 ± 8.6 days (7–41 days). Mortality rate of patients who have no renal recovery was higher (44.8% vs. 4.8%) than renal recovery group (p < 0.01). Conclusion: The AKI represents a frequent complication in the elderly patients with longer hospital stay and increased mortality and morbidity. Our results show that dialytic support requirement is an independent predictor of permeant kidney injury in the elderly AKI patients. Older age, low diastolic blood pressure, high CRP and low hemoglobin levels were independent risk factors for mortality.
Introduction
Acute kidney injury (AKI) is a serious event and most often complicates longer hospitalization.Citation1 AKI is associated with a very high rate of mortality and morbidity.Citation2–4 Incidence of dialysis requiring AKI increased last years, an average increase of 10% per year.Citation5 An important factor for increase in AKI is the older age of the population.
Elderly patients have an increased risk for AKI. The BEST Kidney study showed that advanced age was independently associated with increased hospital mortality in patients with AKI.Citation6 These patients have a lot of comorbid conditions accumulated that can lead to chronic kidney disease (CKD), they are exposed to multiple nephrotoxic medications, they have structural, functional and molecular changes in their kidneys that decrease renal reserve and susceptibility to severe damage.
AKI is largely a disease of the elderly. It was demonstrated that there is 3–8 fold progressive increase in the frequency of AKI in patients older than 60 years.Citation7 The outcomes for elderly patients who develop dialysis requiring AKI are uniformly poor, reported mortality rates ranging from 31% to 80%.Citation8
In one meta-analysis, patients older than 65 years had significantly worse renal function recovery rates than younger patients (31% of elderly patients did not recover kidney function compared to 26% younger patients).Citation9 Other studies have also demonstrated that the rates of renal recovery after AKI are lower in the elderly.Citation10,Citation11
In our cohort we aimed to investigate the outcomes of AKI in the hospitalized patients; hospital mortality, etiology of AKI, rate of initiating renal replacement therapy (RRT), rate of recovery or no recovery in kidney function of the elderly patients with AKI.
Serum creatinine elevations are used to diagnose AKI according to Kidney Disease Improwing Global Outcomes (KDIGO) criteria for the diagnosis of acute kidney injuryCitation12 ().
Box 1. Kidney Disease Improwing Global Outcomes (KDIGO) criteria for the diagnosis of acute kidney injury.
Design
Evidence for this study was obtained from retrospective cohort from our center.
Patients
A total of 193 patients hospitalized (>65 years, mean age: 79.99 ± 6.93) with acute kidney failure were enrolled in this study between 2011 and 2012. Patients with history of kidney failure or renal replacement therapy (RRT) at admission were excluded.
Statistical analysis
Continuous variables were expressed as mean ± standard deviation and discrete variables as frequencies and percentages. One way Anova test, Tukey HDS test, Kruskal–Wallis and Mann–Whitney U test were used for comparing the groups. Independent sample t tests were applied to evaluate the differences in means between the two groups. Pearson chi square test, Exact test and Fisher–Freeman–Halton tests, were used to compare frequencies between the two groups. Multiple logistic regression analysis was used to identify the independent predictors of worse renal recovery, mortality. Parameters having a p value <0.05 in univariate analysis were included in the model. The mean difference for the continuous variables with its corresponding 95% confidence interval was also included in the model. Statistical analyses were performed using NCSS (Number Cruncher Statistical System) 2007&PASS (Power Analysis and Sample Size) 2008 Statistical Software (Kaysville, UT) version.
Results
We identified a total of 193 hospitalized cohorts due to AKI. Characteristics, laboratory, medications, outcomes and results of the patients are presented in .
Table 1. Characteristics of patients.
Table 2. Laboratory parameters.
Table 3. Medications.
Table 4. RRT requirement – recovery.
Table 5. Risk factors for permanent kidney failure.
Table 6. Risk factors for permanent renal failure.
Table 7. Risk factors for mortality.
Table 8. Analysis risk factors for mortality.
The causes of AKI in our elderly patients were: dehydratation (n = 66), vomiting (n = 24), diarrhea (n = 25), cardiorenal (decreased cardiac output) (n = 18), ATN (nephrotoxic) (n = 22), sepsis (n = 15), prostat hyperplasia (n = 17), prostat carcinoma (n = 10) bladder carcinoma (n = 12), hemorrhage (n = 5) and contrast material (n = 1).
The comorbid conditions – DM (p < 0.01), HT (p < 0.05), and dementia (p < 0.05) rates – were higher in prerenal groups than others.
Mortality rate of patients who have no renal recovery was higher (44.8% vs. 4.8%) than renal recovery group (p < 0.01) ().
There were no association between comorbid conditions (DM, CHF, CAD) and medications (diuretics, antihypertensives, antibiotics) for permanent dialysis (p > 0.05) ().
Hemodialysis requirement increased risk factor; odds ratio: 3.21 (%95 CI: 1.37–7.55) for permanent chronic kidney disease.
Patients with mortality have older age (median 83.47) (p = 0.001), lower diastolic blood pressure (p = 0.026), higher CRP (p = 0.04) and lower Hb (p = 0.038) levels ().
Discussion
AKI is a growing disease for the elderly patients, with dramatic increases in the incidence over the past decade. AKI is associated with morbidity and mortality. Hospitalized patients with dialysis requiring AKI are older than their counterparts without dialysis requiring AKI. In one meta-analysis, patients older than 65 years had significantly worse renal function recovery rates than younger patients. Some reports have demonstrated that the rates of renal recovery after AKI are lower in the elderly.
The outcomes for the elderly patients who develop dialysis requiring AKI associated with an increased mortality rates ranges from 31% to 80%.Citation13 In our findings mortality rate of all the patients was 18%. Patients who have no renal recovery had higher mortality rate (44.8% vs. 4.8%) than the renal recovery group. In our study, deaths were higher recorded probably in connection with higher rate of patients with severe comorbidity.
The incidence of comorbid conditions that increase for AKI dramatically increases with age. More seen comorbid conditions were HT (54%), DM (32%), CHF (26%), CAD (12%) and SVA (11%) in our cohorts. The important role of prostatic disease in causing AKI is highlighted by the fact that 35% of AKI cases in patients aged 80–89 years were accounted for this cause in one study.Citation6 In our patients, obstructive AKI due to prostatic disease was lower than (14%) the study by Uchino et al. Prerenal AKI in some series accounts nearly one-third of AKI causes.Citation14 Elderly patients are more prone to the development of volume depletion and dehydration. In our cohort, prerenal AKI rate was higher (60%) than other series.
The contribution of each nephrotoxic medication to the development of AKI was studied. During the course of the study, pharmacological treatments were modified according to the clinical status and renal function of the patient. As a matter of fact, polypharmacy was very common among our patients including angiotensin converting enzyme inhibitors/angiotensin receptor blockers (40%), NSAIDs (29%) PPI (20%) and aminoglycosides (9%), that are known to be associated with nephrotoxic effects.Citation15–17 However, it was not possible to determine individual contribution of these medications due to the multiplicity of combinations.
Patients with AKI may recover completely, require permanent RRT, partially recover, or may die of their acute ilness.Citation18 Recent data have demonstrated that older age is associated with a greater risk of non-recovery of renal function back to baseline and survivors are often left with CKD.Citation2,Citation9,Citation19,Citation20
In our study, after multivariable adjustment, there was no association between comorbid conditions (DM, CHF, CAD) and medications (diuretics, antihypertensives, antibiotics) for permanent dialysis only hemodialysis requirement remained as an independent predictor, for permeant kidney disease or non-recovery. Older age, low diastolic blood pressure, high CRP and low hemoglobin levels were independent risk factors for mortality.
Conclusion
In conclusion, AKI is mostly frequent in the elderly hospitalized patients associated with increased length of hospital stay, mortality and morbidity. Our findings suggest that hemodialysis requiring AKI is an independent predictor for the development of permanent kidney failure; and older age, low diastolic blood pressure, high CRP and low hemoglobin levels were independent risk factors for mortality
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
References
- Lamiere N, Van Biesen W, Wanholder R. Acute kidney injury. Lancet. 2008;372:1863–1865
- Lo LJ, Go AS, Chertow GM, et al. Dialysis requiring acute renal failure increases the risk of progressive chronic kidney disease. Kidney Int. 2009;76:893–899
- Hsu CY, Chertow GM, Mc Culloch CE, et al. Nonrecovery of kidney function and death after acute on chronic renal failure. Clin J Am Soc Nephrol. 2009;4:891–898
- Liangos O, Wald R, O’Bell JW, et al. Epidemiology and outcomes of acute renal failure in hospitalized patients: a national survey. Clin J Am Soc Nephrol. 2006;1:43–51
- Hsu RK, Mc Culloch CE, Dudley RA, et al. Temporal changes in incidence of dialysis requiring AKI. J Am Soc Nephrol. 2013;24(1):37–42
- Uchino S, Kellum JA, Bellomo R, et al. Acute renal failure in critically ill patients: A multinational, multicenter study. JAMA. 2005;294:813–818
- Feest TJ, Round A, Hamad S. Incıdence of severe acute renal failure in adults: Results of a community based study. BMJ. 1993;306:481–489
- Chronopoulos A, Rosner MH, Cruz DN, et al. Acute kidney injury in elderly intensive care patients: A review. Intensive Care Med. 2010;36:1454–1464
- Schmitt R, Coca S, Kanbay M, et al. Recovery of kidney function after acute kidney injury in the elderly: A systematic review and meta-analysis. Am J Kidney Dis. 2008;52:262–271
- Wald R, Quinn RR, Luo J, et al. Chronic dialysis and death among survivors of acute kidney injury requiring dialysis. JAMA. 2009;302:1179–1185
- Macedo E, Bouchard J, Mehta RL. Renal recovery following acute kidney injury. Curr Opin Crit Care. 2008;14:660–665
- Clinical practice guidelines for acute kidney injury 2012. Available at: http//www.kdigo.org/clinical_practice_guidelines/AKI.php. Accessed December 16, 2012
- Groeneweld AB, Tran DD, Van der Meulen J, et al. Acute renal failure in the intensive care unit: Predisposing, complicating factors affecting outcome. Nephron. 1991;59:602–607
- Cheung CM, Ponnusamy A, Anderton JG. Management of acute renal failure in the elderly patient: Aclinican’s guide. Drug Aging. 2008;25:455–462
- Turgut F, Balogun RA, Abdel-Rahman EM. Renin-angiotensin-aldosterone system blockade effects on the kidney in the elderly: Benefits and limitations. Clin J Am Soc Nephrol. 2010;5:1330–1339
- Chang YS. Hypersensitivity reactions to proton pump inhibitors. Curr Opin Allergy Clin Immunol. 2012;4:348–353
- Reis AM, Cassiani SH. Adverse drug events in an intensive care unit of a university hospital. Eur J Clin Pharmacol. 2011;67:625–632
- Rosner MH. Acute kidney injury in the elderly. Clin Geriatr Med. 2013;29:565–578
- Ishani A, Xue JL, Himmelfarb J, et al. Acute kidney injury increases risk of ESRD among elderly. J Am Soc Nephrol. 2009;20:223–228
- Newsome BB, Warnock DG, Mc Clellan WM, et al. Long term risk of mortality and end stage renal disease among the elderly after small increases in serum creatinine level during hospitalization for acute myocardial infarction. Arch Intern Med. 2008;168:609–616