Acute kidney injury in critically ill adults: A cross-sectional study.

Background: Wide differences in the estimates of acute kidney injury (AKI) have been reported in studies from various parts of the world. Due to dearth of data from the region, we carried out the present study to assess the incidence and the associated factors for AKI in our critically ill population.
Methods: A prospective, observational study in critically ill adults who developed AKI was carried out. The diagnosis of AKI was attained by AKI Network (AKIN) criteria. The key details collected included details related to demographics, APCAHE score, concomitant diagnoses, whether mechanical ventilation was provided or not, radiological findings, drugs with potential nephrotoxicity, requirement of renal replacement therapy (RRT), whether recovered from AKI and time taken for recovery, duration of stay in the intensive care unit, and outcome (died/alive).
Results: One hundred patients out of the total 560 with an incidence of 17.9% developed AKI. Forty-five had Stage 1, 22 had Stage 2, and 33 had Stage 3 AKI, and a significantly higher mortality was observed with Stage 3 AKIN Class compared to Stages 1 and 2. Two-thirds of the patients had septic shock, while 29 had contrast-induced nephropathy. Ninety-five patients received at least one drug with potential nephrotoxicity. Sixty-three patients recovered from AKI episodes. Only 29 patients underwent RRT of which 41% died.
Conclusion: We observed an incidence of 17.9% for AKI in our critically ill patients. The estimates from this study will serve as a baseline for future studies in the region. Copyright:

INTRODUCTION

Acute kidney injury (AKI) has been defined as abrupt cessation of kidney function. AKI has been observed in around one-third to half of critically ill adults with a 90-day mortality of around 23%.[12] Increasing trend in the incidence of AKI has been observed in critically ill adults; however, mortality risk reduces owing to improved treatment strategies.[3] A multicenter study with large majority of nations from Europe revealed that more than 200 definitions of AKI were followed in the critical care units.[4] However, recently, Kidney Disease: Improving Global Outcomes guidelines; Risk, Injury, Failure, Loss, and End-stage Kidney; or AKI Network (AKIN) classification is widely followed.[5] Elderly age, sepsis, hypotension, hypovolemia, chronic kidney disease, congestive heart failure, diabetes mellitus, and presence of drugs with potential nephrotoxicity are the risk factors associated with AKI.[6] Considering the dearth of data from Bahraini population, we carried out the present study to evaluate the factors identified with AKI in our critically ill patients.

METHODS

Study design and ethics

This study was a prospective, observational study carried out in the adult intensive care unit (ICU) of the largest healthcare center in the Kingdom of Bahrain between January 1 and May 31, 2021. The study was carried out after obtaining approval from the Institutional Ethics Committee and written consent from either the patients or their legally accepted representatives.

Study participants and procedure

Adult patients (>18 years) of either sex admitted in the ICU with baseline normal renal function as defined by their serum creatinine values were included in this study if they develop AKI as per the AKIN criteria [Table 1].[7] Those with prior history of chronic renal failure/injury or previous episodes of AKI were excluded. The following details were captured for each of the study participants: demographics (age and sex), body weight, height, body mass index, APCAHE score, concomitant diagnoses, whether mechanical ventilation was provided or not, radiological findings, drugs with potential nephrotoxicity, requirement of renal replacement therapy (RRT), whether recovered from AKI and time taken for recovery, duration of stay in the ICU, and outcome (died/alive).

Table 1

Stages of acute kidney injury as per Acute Kidney Injury Network Criteria

Stages	Serum creatinine	Urine output
1	1.5-1.9 times baseline or >0.3 mg/dl increase	<0.5 ml/kg/h for 6-12 h
2	2-2.9 times baseline	<0.5 ml/kg/h for >12 h
3	>3 times baseline or >4 mg/dl or dialysis	<0.3 ml/kg/h for >24 h or anuria for >12 h

Statistical analyses

Descriptive statistics were used for representing the demographic variables. Chi-square test of association was used for evaluating the association between AKIN stages, requirement of RRT, and the risk of mortality. A P ≤ 0.05 was considered statistically significant. SPSS (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY, USA: IBM Corp.) was used for statistical analysis.

RESULTS

Demographics

A total of 560 admissions were observed during the study period of which 100 (17.9%) were identified with AKI. The demographic characteristics of these 100 patients are represented in Table 2. The following diagnoses were observed among the study participants: community-acquired pneumonia (n = 25), septic shock (n = 14), acute chest syndrome/vaso-occlusive crisis (n = 9), postoperative following major surgeries (n = 8), polytrauma (n = 5), acute stroke (n = 5), acute pancreatitis (n = 5), diabetic ketoacidosis (n = 4), morphine overdose (n = 2), and obstructive jaundice (n = 2), and one each was admitted for acute asthma, burns, H1N1 influenza, anaphylactic shock, pyelonephritis, placental abruption, acute gastroenteritis/hemolytic–uremic syndrome, acute myocardial infarction, hepatic encephalopathy, intestinal obstruction, sepsis, transverse myelitis, pulmonary embolism, Goodpasture syndrome, organophosphate poisoning, meningoencephalitis, lupus nephritis, and gangrenous cholecystitis. The following concomitant diseases were observed: diabetes mellitus (n = 29), systemic hypertension (n = 33), sickle cell disease (n = 13), cerebrovascular accident (n = 5), chronic obstructive pulmonary airway disease (n = 3), hypothyroidism (n = 3), epilepsy (n = 3), ischemic heart disease (n = 2), chronic liver disease (n = 2), tuberculosis (n = 1), Type 2 respiratory failure (n = 1), pulmonary hypertension (n = 1), multiple sclerosis (n = 1), multiple myeloma (n = 1), alcoholic liver disease (n = 1), and dilated cardiomyopathy (n = 1).

Table 2

Demographic characteristics of the study participants (n=100)

Parameters	Values
Age (years)	50 (18-95)
Male:female (n)	64:36
Body weight (kg)	75 (27-160)
Height (cm)	164 (100-185)
BMI (kg/m2)	27.7 (12-54.1)
APACHE II score	13 (1-26)
Number of patients requiring mechanical ventilation (n)	83
Duration of ICU stay (days)	10 (1-55)

The values are represented in median (range) unless specified otherwise. BMI: Body mass index, ICU: Intensive care unit, APACHE II: Acute Physiology and Chronic Health Evaluation II

Stages and causes of acute kidney injury

Forty-five met the criteria for Stage 1, 22 for Stage 2, and 33 for Stage 3 AKI. Sixty patients had septic shock, 29 had contrast-induced nephropathy, 11 had hypovolemic shock, six had hepatorenal syndrome, three had cardiorenal syndrome, two had hemolytic–uremic syndrome, and one each had obstructive nephropathy, pyelonephritis, multiple myeloma, lupus nephritis, and drug-induced (colistin). Median (range) time of onset of AKI from the time of admission in the ICU was 1 (1–17) days. Twenty-nine patients required continuous RRT. No significant association was observed between mechanical ventilation and the stages of AKI (1-38/45 [84.4%], 2-15/22 [68.2%], and 3-30/33 [90.9%]; P = 0.08).

Computed tomography was carried out in four patients, of which no abnormality was detected in three, and one had renal injury. Ultrasound imaging revealed no abnormalities in 24 patients, and one each had hydronephrosis, bilateral perinephric free fluid, and obstructive uropathy. None of them underwent renal biopsy investigation.

Potential nephrotoxic medicines administered to study participants

Ninety-five patients received one or more of potential nephrotoxic medicines as depicted in Figure 1. Meropenem followed by furosemide was the most administered potentially nephrotoxic drug. In 82 patients, such drugs were stopped as soon as AKI was diagnosed, and in 17 patients, a dose/frequency of drug administration was reduced.

Figure 1

Potential nephrotoxic medicines received before acute kidney injury was diagnosed. This Pareto chart represents the number of patients receiving one or more drugs with potential nephrotoxicity arranged in the ascending order

Outcomes

Twenty-nine patients required RRT (eight [17.8%] with Stage 1, six [27.3%] with Stage 2, and 15 [45.5%] with Stage 3 AKI; P = 0.02). Mortality rate was significantly higher among those who underwent RRT compared to those who did not (16/39 [41%], 20/71 [28.2%]; P = 0.0001). Sixty-three patients recovered from AKI and 36 died. Median (range) recovery time for the study participants was 6 (2–65) days. Nine out of 45 (20%) patients with AKIN Stage 1, 7/22 (31.8%) patients with Stage 2, and 20/33 (39.4%) patients with Stage 3 died (P = 0.0001).

DISCUSSION

We carried out an observational study evaluating critically ill adults diagnosed with AKI and observed an incidence of 17.9%. Forty-five had Stage 1, 22 had Stage 2, and 33 had Stage 3 AKI, and a significantly higher mortality was observed with Stage 3 AKIN Class compared to Stages 1 and 2. Two-thirds of the patients had septic shock, while 29 had contrast-induced nephropathy. Ninety-five patients received at least one drug with potential nephrotoxicity. Sixty-three patients recovered from AKI episodes. Only 29 patients underwent RRT of which 41% died.

Wide variations are observed in the incidences of AKI reported from various nations. However, the incidence observed in the present study is comparable to other reports.[8] However, few other studies, particularly from the Western world, have reported a higher incidence to an extent of around 39%.[9] The differences in the incidence of AKI are primarily attributed to the differences in the guidelines adhered in defining AKI. We observed that only 29 patients required RRT, and a significantly higher risk of death was observed in this group. This could be explained by the severity of AKI among those who underwent RRT as most of them were AKIN Stage 3.

Medications are an important causative factor for AKI. We observed that almost 95 of the total 100 patients have received one or more of the potential nephrotoxic drugs. Drugs lead to nephrotoxicity by tubular/tubule–interstitial injury.[10] Incidence of AKI is very high among critically ill patients receiving nephrotoxic drugs. A nested case–control study from 1001 patients in the ICU estimated that 617 (62%) patients received at least one nephrotoxic drug, and 303 (30%) received two or more; and the authors observed AKI in 61% of these patients.[11] More vigilance is required in frequent monitoring and early recognition of AKI in patients receiving such nephrotoxic drugs.

The study is limited in not comparing the risk factors between those who had developed AKI with those who did not.

CONCLUSION

The present study is the first evaluating the prevalence and the associated factors for AKI amongst the critically ill Bahraini population. The estimates from this study will serve as a baseline for future studies in the region.

Research quality and ethics statement

This study was approved by the Institutional Review Board/Ethics Committee at Salmaniya Medical Complex (Approval # 16/19; Approval date December 31, 2019). The authors followed the applicable EQUATOR Network (http://www.equator-network.org/) guidelines, specifically the STROBE Guidelines, during the conduct of this research project.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.