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Introduction: Acute kidney injury (AKI) rarely occurs in isolation in critically ill patients and has a multifactorial etiology. Its incidence is increasing and is associated with considerable morbidity and mortality. Renal support therapies (RST) have become a routine and essential measure for managing patients in the intensive care unit (ICU). It is applied in 23.50% of patients with AKI (i.e., 13.5% of all ICU admissions), and its utilization has increased by more than 10% per year over the last decade. There are controversies regarding the optimal modality of RST, and there is no clear evidence on long-term outcomes. However, both intermittent dialysis and hybrid forms, as well as continuous therapy, can be used interchangeably.
Objective: To analyze the epidemiological profile for the development of AKI-D (acute kidney injury treated with dialysis) in a population of critically ill patients and explore predictors of mortality.
An epidemiological, observational, retrospective study was conducted on 113 adult patients admitted to the British Hospital (Buenos Aires, Argentina) between January and December 2021, requiring renal support therapy (RST). Epidemiological, clinical, and laboratory data were obtained from the hospital's computer system.
Variables analyzed included: Gender, age, baseline glomerular filtration rate (GFR), reason for ICU admission, need for mechanical ventilation, PaO2/FiO2 ratio, SOFA score, APACHE II score, need for vasoactive drugs, reason and modality of renal replacement therapy, intradialytic hypotension (IDH) events, mortality, and progression to end-stage renal disease.
A Multiple Linear Regression model was used since the variable to predict is quantitative (days of dialysis). The chosen predictor variables were Age, APACHE II, SOFA, and baseline GFR.
Additionally, a Logistic Regression model was used to predict mortality (a dichotomous variable). The selected predictor variables were Age, APACHE II, SOFA, baseline GFR, Number of dialysis sessions, Albumin value at admission, and IDH events.
The study included 113 patients over a 12-month period, 74% male, with a median age of 70 years (IQR 63-67). The reason for ICU admission was medical in 88.50% of cases. The median APACHE II score was 18 (IQR 14-21), SOFA median of 12 (IQR 9-14), and PaO2/FiO2 median of 190 (IQR 150-276). Vasopressors were used in 67.26% of the population. The median total days of hospitalization were 22 (IQR 12-37), and days in the ICU were 18 (IQR 6.5-29.5).
Initiation criteria for RST were uremia in 42.99%, fluid removal need 39.25%, hyperkalemia 8.41%, metabolic acidosis 3.74%, anuria 2.80%, hypernatremia 1.87%, and intoxication 0.93%. The median days between the start and end of dialysis were 10 days (IQR 3-20), maintaining a negative balance in 54.72% of patients. A total of 1154 dialytic treatments were performed, with hemodialysis (HD) being the most used modality (47%), followed by extended high-flux hemodiafiltration (HDF) at 22%, extended HD at 17%, and HDF at 10%. The total days of continuous renal replacement therapy (CRRT) were 46 (4%). The recorded mortality was 64.60% (73). Of the survivors, 10 patients (8.85%) remained on dialysis. Among those depending on high-flux dialysis, the median GFR was 49.1 ml/min/1.73 m2 (median baseline GFR of 70 ml/min/1.73 m2, IQR 43.8-93). No significant difference was observed in relation to the chosen RST modality.
The multivariable model did not find a correlation between Age, APACHE II, SOFA, and baseline GFR to predict more days of dialysis. As predictors of mortality, the variables Age, APACHE II, SOFA, baseline GFR, Number of dialysis sessions, Albumin value at admission, and IDH events were analyzed. The equation yielded a statistically significant result for IDH events as a predictor of mortality (p=0.0002) with a 95% confidence interval.
This study allowed for the description of the characteristics and clinical evolution of patients with KDIGO stage III AKI admitted to the ICU requiring RST. Mortality was 64.60%, and survivors who remained on dialysis were 8.85%. We found no significant differences regarding the RST modality performed, nor predictors for more days of dialysis. However, when analyzing predictors of mortality, the equation shows a statistically significant relationship for IDH events.