Risk factors for the development of acute kidney injury in patient groups between 65-80 years and over 80 years and factors affecting renal survival

Introduction and Aim: AKI is a clinical picture associated with accumulation of nitrogenous waste products secondary to sudden deterioration in kidney function as well as deterioration in extracellular fluid, electrolyte and acid- base balance other consequences of renal dysfunction. Risk factors, etiology, clinical findings and also outcome may differ in the elderly population. The aim of our study is to determine the risk factors for the development of AKI, to determine the factors affecting the course of the disease and to determine the determinants of the outcome in patients aged 65 and more. Materials and Methods: Patients aged 65 and over who were hospitalized for AKI or who developed AKI during hospitalization were evaluated in our study. Patients under 65 years of age or who did not give consent were excluded. The etiologies of AKI, reason(s) for hospitalization, comorbidities, the medications used by the patients, the follow-up period after the diagnosis of AKI, drugs or medical practices that may affect kidney functions during hospitalization, systolic and diastolic blood pressures and serum urea and creatinine levels, and eGFR at the time of discharge were recorded for each patient included. Patients over 80 years of age, which can be defined as advanced elderly group, were compared in terms of the study parameters with the patients aged 65-80 years. Since the distribution was not normal, the comparison of numerical parameters between two independent groups was performed by Mann Whitney U test. The ratios in the groups were analyzed with the Chi-Square test. Survival rates were calculated by Kaplan Meier Analysis. Risk factors were analyzed by Cox Regression Analysis. Statistical alpha significance level was accepted as p<0.05. Results: 196 patients were included in the study (103 female, 93 male). The mean age was 72,5±4,4 years. 148 patients were between 65-80 years age group while 48 patients were over 80 years old. 83 (56,1%) of the patients had underlying CKD. Basal creatinine levels of the patients were 1,30±0,57 mg/dl, creatinine level at time of diagnosis was 3,43±4,35 mg/dl, mean systolic and diastolic blood pressures were 125,9±31,6 mmHg and 68,8±17,7 mmHg, respectively. It was determined that 100 (51,0%) of the patients had stage-2, 53 (27,0%) stage-3 and 43 (21,9%) stage-1 AKI. Age groups were found to be similar in terms of AKI stage. AKI etiology was recorded as prerenal causes (56,6%) most frequently. There was no difference between age subgroups in terms of etiology groups. It was observed that the most common prerenal cause was dehydration due to lack of oral intake (29,1%), and nephrotoxin exposure (26,0%) was the most common intrinsic renal cause. The three most common reasons for hospitalization were determined as genitourinary system diseases, infections and cardiovascular system diseases. Among the patients over 80 years of age, the most common reason for hospitalization was infections, followed by genitourinary system diseases and cardiovascular diseases. The difference between age groups was not statistically significant. The three most common comorbid diseases were hypertension, DM and CKD in order, and in the analysis of age groups, this ranking was hypertension, CKD and ischemic heart disease in the age group over 80 years old. However, the difference was not statistically significant. The three most commonly used drug groups were beta- blockers, diuretics and RAAS blockers in order. There was no difference between age groups in terms of drug groups. When the outcomes of the patients at the time of discharge were examined, 74,9% of the total patient group recovered (40,3% complete and 34,6% partial), while 9.6% of the patients were discharged as dialysis-dependent renal failure patients, and 15,3% of the patients died. When the patient outcomes in the 65-80 age group were examined, it was observed that complete recovery was less frequent, dialysis-dependent renal failure was more frequent, and the frequency of death was lower in patients with CKD at baseline (p<0,021). The mortality rate was found to be significantly higher in patients with sepsis (p<0,001). It was observed that the rate of complete recovery rate decreased as the AKI stage progressed, while the frequency of dialysis-dependent renal failure and death increased (p<0,001). It was determined that complete recovery was less frequent, dialysis-dependent renal failure was more common, and death was less frequent in patients whose hospitalization reason was genitourinary system diseases (p<0,003). It was determined that the recovery rates were lower in patients with malignancy, and the frequency of dialysis-dependent renal failure and death was more frequent (p<0,023). Mortality rate was lower in patients using beta blockers (p<0,025). It was found that recovery rates were higher in nonoliguric patients, and dialysis-dependent renal failure and mortality rates were lower (p<0,001). In the subgroup analyzes performed according to gender, etiology, AKI stage, comorbid diseases, and oliguria in the group over 80 years of age, no difference was found in terms of outcome. The mortality rate was lower in patients using dihydropyridine group calcium channel blockers (p<0,033), and it was seen that partial recovery was more frequent in patients using RAAS blockers (p<0,031) or beta blocker (p<0,006), complete recovery was less, and dialysis-dependent renal failure and death rates were higher. According to Cox regression analysis, the main risk factors for no improvement (dialysis-dependent renal failure or death) were aminoglycoside use (p<0,001) and presence of DM (p<0,032) in the 65-80 age group; while these factors were heart failure (p<0,004), hospitalization for cardiovascular diseases (p<0,001) and colistin use (p<0,026) in the group over 80 years of age. Being nonoliguric reduced the risk of non-healing (p<0,003) in the 65-80 age group while it was observed that there was no effect in the group over 80 years of age (p<0,078). While there was no effect of AKI stages in the group over 80 years of age, it was observed that stage-2 AKI had a protective effect when compared to stage-3 AKI in the 65-80 age group (p<0,009). When the factors related to death were examined by Cox regression analysis, it was determined that the risk was higher in aminoglycoside- induced AKI and in those using nondihydropyridine calcium channel blockers, and lower in those who had a nonoliguric course. In multivariate analysis, background CKD (p<0,048) and being nonoliguric (p<0,005) was detected to have a protective effect for death or dialysis-dependent renal failure. Conclusion: The geriatric population is more vulnerable to AKI for many reasons. AKI prognosis is worse in this patient group, and as we reported in our study, dialysis-dependent renal failure and mortality rates are high. Particularly, systemic diseases such as sepsis, heart failure, and the use of nephrotoxic drugs can trigger the development of AKI, and adversely affect the prognosis as well. Therefore, the first goal in the geriatric patient population should be to prevent AKI. For this purpose, the goals of all clinicians are effective treatment of comorbid diseases, avoiding nephrotoxic agents, avoiding multiple drug use, and being careful about drug doses and applications. Another important point is the high awareness of dehydration, which is reported as the most common cause of AKI in elderly patients, careful titration of the dose of drug groups such as diuretics that may affect volume status, and the search for methods to cope with oral intake deficiencies that may be encountered in frequently seen geriatric syndromes. Keywords: Acute kidney injury, chronic kidney injury, old age, mortality, sepsis, dehydration.