Carol George

A comparison of the RIFLE and AKIN criteria for acute kidney injury in critically ill patients

BACKGROUND The Acute Dialysis Quality Initiative Group has published a consensus definition/classification system for acute kidney injury (AKI) termed the RIFLE criteria. The Acute Kidney Injury Network (AKIN) group has recently proposed modifications to this system. It is currently unknown whether there are advantages between these criteria. METHODS We interrogated the Australian New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD) for all adult admissions to 57 ICUs from 1 January 2000 to 31 December 2005. We compared the performance of the RIFLE and AKIN criteria for diagnosis and classification of AKI and for robustness of hospital mortality. RESULTS We included 120 123 critically ill patients, of which 27.8% had a primary diagnosis of sepsis. We found only small differences (<1%) in the number of patients classified as having some degree of kidney injury using either the AKIN or RIFLE definition or classification systems. AKIN slightly increased the number of patients classified as Stage I injury (category R in RIFLE) (from 16.2 to 18.1%) but decreased the number of patients classified as having Stage II injury (category I in RIFLE) (13.6% versus 10.1%). The area under the ROC curve for hospital mortality was 0.66 for RIFLE and 0.67 for AKIN in all patients and it was 0.65 for both in septic patients. CONCLUSION Compared to the RIFLE criteria, the AKIN criteria do not materially improve the sensitivity, robustness and predictive ability of the definition and classification of AKI in the first 24 h after admission to ICU.

Early acute kidney injury and sepsis: a multicentre evaluation

IntroductionWe conducted a study to evaluate the incidence, risk factors and outcomes associated with early acute kidney injury (AKI) in sepsis.MethodsThe study was a retrospective interrogation of prospectively collected data from the Australian New Zealand Intensive Care Society Adult Patient Database. Data were collected from 57 intensive care units (ICUs) across Australia. In total, 120,123 patients admitted to ICU for more than 24 hours from 1 January 2000 to 31 December 2005 were included in the analysis. The main outcome measures were clinical and laboratory data and outcomes.ResultsOf 120,123 patients admitted, 33,375 had a sepsis-related diagnosis (27.8%). Among septic patients, 14,039 (42.1%) had concomitant AKI (septic AKI). Sepsis accounted for 32.4% of all patients with AKI. For septic AKI stratified by RIFLE (risk of renal failure, injury to the kidney, failure of kidney function, loss of kidney function and end-stage kidney disease) category, 38.5% of patients belonged to the risk category, 38.8% to the injury category and 22.7% to the failure category. Septic AKI patients had greater acuity of illness (P < 0.0001), lower blood pressure (P < 0.0001), higher heart rates (P < 0.0001), worse pulmonary function measures by arterial oxygen tension/fraction of inspired oxygen ratio (P < 0.0001), greater acidaemia (P < 0.0001) and higher white cell counts (P < 0.0001) compared with patients with nonseptic AKI. Septic AKI was also associated with greater severity of AKI (RIFLE category injury or failure) compared with nonseptic AKI. Septic AKI was associated with a significantly higher crude and co-variate adjusted mortality in the ICU (19.8% versus 13.4%; odds ratio 1.60, 95% confidence interval 1.5 to 1.7; P < 0.001) and in hospital (29.7% versus 21.6%; odds ratio 1.53, 95% confidence interval 1.46 to 1.60; P < 0.001) compared with nonseptic AKI. Septic AKI was associated with higher ICU and hospital mortality across all strata of RIFLE categories. Septic AKI patients had longer durations of stay in both ICU and hospital across all strata of RIFLE categories.ConclusionSeptic AKI is common during the first 24 hours after ICU admission. Patients with septic AKI are generally sicker, with a higher burden of illness, and have greater abnormalities in acute physiology compared with patients with nonseptic AKI. Moreover, septic AKI is independently associated with higher odds of death and longer duration of hospitalization.

Very old patients admitted to intensive care in Australia and New Zealand: a multi-centre cohort analysis.

IntroductionOlder age is associated with higher prevalence of chronic illness and functional impairment, contributing to an increased rate of hospitalization and admission to intensive care. The primary objective was to evaluate the rate, characteristics and outcomes of very old (age ≥ 80 years) patients admitted to intensive care units (ICUs).MethodsRetrospective analysis of prospectively collected data from the Australian New Zealand Intensive Care Society Adult Patient Database. Data were obtained for 120,123 adult admissions for ≥ 24 hours across 57 ICUs from 1 January 2000 to 31 December 2005.ResultsA total of 15,640 very old patients (13.0%) were admitted during the study. These patients were more likely to be from a chronic care facility, had greater co-morbid illness, greater illness severity, and were less likely to receive mechanical ventilation. Crude ICU and hospital mortalities were higher (ICU: 12% vs. 8.2%, P < 0.001; hospital: 24.0% vs. 13%, P < 0.001). By multivariable analysis, age ≥ 80 years was associated with higher ICU and hospital death compared with younger age strata (ICU: odds ratio (OR) = 2.7, 95% confidence interval (CI) = 2.4 to 3.0; hospital: OR = 5.4, 95% CI = 4.9 to 5.9). Factors associated with lower survival included admission from a chronic care facility, co-morbid illness, nonsurgical admission, greater illness severity, mechanical ventilation, and longer stay in the ICU. Those aged ≥ 80 years were more likely to be discharged to rehabilitation/long-term care (12.3% vs. 4.9%, OR = 2.7, 95% CI = 2.6 to 2.9). The admission rates of very old patients increased by 5.6% per year. This potentially translates to a 72.4% increase in demand for ICU bed-days by 2015.ConclusionsThe proportion of patients aged ≥ 80 years admitted to intensive care in Australia and New Zealand is rapidly increasing. Although these patients have more co-morbid illness, are less likely to be discharged home, and have a greater mortality than younger patients, approximately 80% survive to hospital discharge. These data also imply a potential major increase in demand for ICU bed-days for very old patients within a decade.

Changes in the incidence and outcome for early acute kidney injury in a cohort of Australian intensive care units

IntroductionThere is limited information on whether the incidence of acute kidney injury (AKI) in critically ill patients has changed over time and there is controversy on whether its outcome has improved.MethodsWe interrogated the Australian New Zealand Intensive Care Society Adult Patient Database to obtain data on all adult admissions to 20 Australian intensive care units (ICUs) for ≥ 24 hours from 1 January 1996 to 31 December 2005. Trends in incidence and mortality for ICU admissions associated with early AKI were assessed.ResultsThere were 91,254 patient admissions to the 20 study ICUs, with 4,754 cases of AKI, for an estimated crude cumulative incidence of 5.2% (95% confidence interval, 5.1 to 5.4). The incidence of AKI increased during the study period, with an estimated annual increment of 2.8% (95% confidence interval, 1.0 to 5.6, P = 0.04). The crude hospital mortality was significantly higher for patients with AKI than those without (42.7% versus 13.4%; odds ratio, 4.8; 95% confidence interval, 4.5 to 5.1; P < 0.0001). There was also a decrease in AKI crude mortality (annual percentage change, -3.4%; 95% confidence interval, -4.7 to -2.12; P < 0.001), however, which was not seen in patients without AKI. After covariate adjustment, AKI remained associated with a higher mortality (odds ratio, 1.23; 95% confidence interval, 1.14 to 1.32; P < 0.001) and there was a declining trend in the odds ratio for hospital mortality.ConclusionOver the past decade, in a large cohort of critically ill patients admitted to 20 Australian ICUs, there has been a significant rise in the incidence of early AKI while the mortality associated with AKI has declined.

Early blood glucose control and mortality in critically ill patients in Australia

Objective:To measure temporal trends in blood glucose (BG) control and describe their association with hospital mortality in a cohort of critically ill patients from Australia. Design:Interrogation of prospectively collected data from the Australia New Zealand Intensive Care Society Adult Patient Database. Setting:Twenty-four intensive care units (ICU) across Australia. Patients and Participants:A cohort of 66,184 adult ICU admissions for ≥24 hours from January 1, 2000, to December 31, 2005. Interventions:None. Measurements and Main Results:Highest and lowest BG values within 24 hours of ICU admission, standard demographic, clinical, and physiologic data, and hospital mortality. Medical, mechanically ventilated surgical, cardiac surgical, and septic subgroups were evaluated. Average BG was evaluated as a continuous variable and by quartiles (low [<5.6 mmol/L], near normal [5.6–8.69 mmol/L], high [8.69–11.79 mmol/L], and highest [>11.79 mmol/L]). There were 132,368 BG values, with a mean (95% confidence intervals) value 8.69 mmol/L (8.66–8.73). There was no trend in BG for the entire cohort (p = 0.66) over the study period; yet, BG increased after 2002 (0.17 mmol/L, p < 0.0001). The mechanically ventilated surgical and cardiac surgical subgroups had decreasing trends in BG (p < 0.001), whereas the septic subgroup had an increasing BG trend (p < 0.001). BG in the low, high, and highest quartiles, compared with the near-normal quartile, were consistently associated with higher hospital mortality in crude (odds ratio 1.31, 1.58, and 2.00) and multivariable analysis (odds ratio 1.29, 1.07, and 1.10), respectively. This association was similarly shown for the mechanically ventilated surgical and cardiac surgical subgroups. Conclusions:In a large cohort of ICU patients from Australia, there was no significant change in early glycemic control from 2000 to 2005. There were differences in selected subgroups. Average BG decreased in surgical subgroups, whereas it increased in septic patients. Both high and early low BG values were independently associated with hospital mortality.

Mortality and length-of-stay outcomes, 1993-2003, in the binational Australian and New Zealand intensive care adult patient database*

Objective:Intensive care unit (ICU) outcomes have been the subject of controversy. The objective was to model hospital mortality and ICU length-of-stay time-change of patients recorded in the Australian and New Zealand Intensive Care Society adult patient database. Design:Retrospective, cohort study of prospectively collected data on index patient admissions. Setting:Australian and New Zealand ICUs, 1993–2003. Patients:The Australian and New Zealand Intensive Care Society adult patient database, which contains data for 223,129 patients. Interventions:None. Measurements and Main Results:Hospital mortality and ICU length of stay were modeled using logistic and linear regression, respectively, with determination (80%) and validation (20%) data sets. Model adequacy was assessed by discrimination (receiver operating characteristic curve area, AZ) and calibration (Hosmer-Lemeshow Ĉ) for mortality and R2 for length of stay. Predictor variables included patient demographics, severity score, surgical and ventilation status, ICU categories, and geographical locality. The data set comprised 223,129 patients: Their mean (sd) age was 59.2 (18.9) yrs, 41.7% were female, their mean (sd) Acute Physiology and Chronic Health Evaluation (APACHE) III score was 53 (31), they had 16.1% overall mortality rate, and 45.7% were mechanically ventilated. ICU length of stay was 3.6 (5.6) days. AZ, Ĉ statistic, and R2 for developmental and validation model data sets were 0.88, 17.64 (p = .02), and 0.18; and 0.88, 12.32 (p = .26), and 0.18, respectively. Variables with mortality impact (p ≤ .001) were age (odds ratio [OR] 1.023), gender (OR 1.16; males vs. females), APACHE III score (OR 1.06), mechanical ventilation (OR 1.66), and surgical status (elective, OR 0.17; emergency, OR 0.47; compared with nonsurgical). ICU level and locality had significant mortality-time effects. Similar variables were found to predict length of stay. Risk-adjusted mortality declined, during 1993–2003, from 0.19 (95% confidence interval 0.17–0.21) to 0.15 (0.13–0.16) and similarly for ventilated patients: 0.26 (0.24–0.29) to 0.23 (0.21–0.25). Predicted mean ICU length of stay (days) demonstrated minimal overall time-change: 3.4 (2.2) in 1993 to 3.5 (2.7) in 2003, peaking at 3.7 (2.4) in 2000. Conclusions:Overall hospital mortality rate in patients admitted to Australian and New Zealand ICUs decreased 4% over 11 yrs. A similar trend occurred for mechanically ventilated patients. Length of stay changed minimally over this period.

A multi-center evaluation of early acute kidney injury in critically ill trauma patients.

Rationale. Few studies have evaluated the epidemiology of acute kidney injury (AKI) in trauma. Objective. To evaluate the incidence, risk factors, and outcomes associated with early AKI (evident within 24 hours of admission) in critically ill trauma patients. Methods. A retrospective interrogation of prospectively collected data from the Australian New Zealand Intensive Care Society Adult Patient Database. A total of 9,449 trauma patients were admitted for ≥24 hours to 57 intensive care units across Australia from January 1st, 2000, to December 31st, 2005. Main Findings. The crude incidence of AKI was 18.1% (n = 1,711). Older age, female sex (OR 1.60, 95% CI, 1.43–1.78, p < 0.0001), and the presence of co-morbid illness (OR 2.70, 95% CI 2.3–3.2, p < 0.0001) were associated with higher odds of AKI. Those with trauma not associated with brain injury (OR 2.40, 95% CI, 2.1–2.7, p < 0.0001) and a higher illness severity (OR 1.12, 95% CI, 1.11–1.12, p < 0.001) also had higher likelihood of AKI. Overall, AKI was associated with a higher crude mortality (16.7% vs. 7.8%, OR 2.36, 95% CI, 2.0–2.7, p < 0.001). Each RIFLE category of AKI was independently associated with hospital mortality in multi-variable analysis (risk: OR 1.69; injury OR 1.88; failure 2.29). Conclusions. Trauma admissions to ICU are frequently complicated by early AKI. Those at high risk for AKI appear to be older, female, with co-morbid illnesses, and present with greater illness severity. Early AKI in trauma is also independently associated with higher mortality. These data indicate a higher burden of AKI than previously described.

Introduction of Medical Emergency Teams in Australia and New Zealand: a multi-centre study

IntroductionInformation about Medical Emergency Teams (METs) in Australia and New Zealand (ANZ) is limited to local studies and a cluster randomised controlled trial (the Medical Emergency Response and Intervention Trial [MERIT]). Thus, we sought to describe the timing of the introduction of METs into ANZ hospitals relative to relevant publications and to assess changes in the incidence and rate of intensive care unit (ICU) admissions due to a ward cardiac arrest (CA) and ICU readmissions.MethodsWe used the Australian and New Zealand Intensive Care Society database to obtain the study data. We related MET introduction to publications about adverse events and MET services. We compared the incidence and rate of readmissions and admitted CAs from wards before and after the introduction of an MET. Finally, we identified hospitals without an MET system which had contributed to the database for at least two years from 2002 to 2005 and measured the incidence of adverse events from the first year of contribution to the second.ResultsThe MET status was known for 131 of the 172 (76.2%) hospitals that did not participate in the MERIT study. Among these hospitals, 110 (64.1%) had introduced an MET service by 2005. In the 79 hospitals in which the MET commencement date was known, 75% had introduced an MET by May 2002. Of the 110 hospitals in which an MET service was introduced, 24 (21.8%) contributed continuous data in the year before and after the known commencement date. In these hospitals, the mean incidence of CAs admitted to the ICU from the wards changed from 6.33 per year before to 5.04 per year in the year after the MET service began (difference of 1.29 per year, 95% confidence interval [CI] -0.09 to 2.67; P = 0.0244). The incidence of ICU readmissions and the mortality for both ICU-admitted CAs from wards and ICU readmissions did not change. Data were available to calculate the change in ICU admissions due to ward CAs for 16 of 62 (25.8%) hospitals without an MET system. In these hospitals, admissions to the ICU after a ward CA decreased from 5.0 per year in the first year of data contribution to 4.2 per year in the following year (difference of 0.8 per year, 95% CI -0.81 to 3.49; P = 0.3).ConclusionApproximately 60% of hospitals in ANZ with an ICU report having an MET service. Most introduced the MET service early and in association with literature related to adverse events. Although available in only a quarter of hospitals, temporal trends suggest an overall decrease in the incidence of ward CAs admitted to the ICU in MET as well as non-MET hospitals.

Landmark survival as an end-point for trials in critically ill patients – comparison of alternative durations of follow-up: an exploratory analysis

IntroductionInterventional ICU trials have followed up patients for variable duration. However, the optimal duration of follow-up for the determination of mortality endpoint in such trials is uncertain. We aimed to determine the most logical and practical mortality end-point in clinical trials of critically ill patients.MethodsWe performed a retrospective analysis of prospectively collected data involving 369 patients with one of the three specific diagnoses (i) Sepsis (ii) Community acquired pneumonia (iii) Non operative trauma admitted to the Royal Perth Hospital ICU, a large teaching hospital in Western Australia (WA cohort). Their in-hospital and post discharge survival outcome was assessed by linkage to the WA Death Registry. A validation cohort involving 4609 patients admitted during same time period with identical diagnoses from 55 ICUs across Australia (CORE cohort) was used to compare the patient characteristics and in-hospital survival to look at the Australia-wide applicability of the long term survival data from the WA cohort.ResultsThe long term outcome data of the WA cohort indicate that mortality reached a plateau at 90 days after ICU admission particularly for sepsis and pneumonia. Mortality after hospital discharge before 90 days was not uncommon in these two groups. Severity of acute illness as measured by the total number of organ failures or acute physiology score was the main predictor of 90-day mortality. The adjusted in-hospital survival for the WA cohort was not significantly different from that of the CORE cohort in all three diagnostic groups; sepsis (P = 0.19), community acquired pneumonia (P = 0.86), non-operative trauma (P = 0.47).ConclusionsA minimum of 90 days follow-up is necessary to fully capture the mortality effect of sepsis and community acquired pneumonia. A shorter period of follow-up time may be sufficient for non-operative trauma.

Improved outcomes from acute severe asthma in Australian intensive care units (1996 – 2003)

Background: There is limited information on changes in the epidemiology and outcome of patients with asthma admitted to intensive care units (ICUs) in the last decade. A database sampling intensive care activity in hospitals throughout Australia offers the opportunity to examine these changes. Methods: The Australian and New Zealand Intensive Care Society Adult Patient Database was examined for all patients with asthma admitted to ICUs from 1996 to 2003. Demographic, physiological and outcome information was obtained and analysed from 22 hospitals which had submitted data continuously over this period. Results: ICU admissions with the primary diagnosis of asthma represented 1899 (1.5%) of 126 906 admissions during the 8-year period. 36.1% received mechanical ventilation during the first 24 h. The overall incidence of admission to ICU fell from 1.9% in 1996 to 1.1% in 2003 (p<0.001). Overall hospital mortality was 3.2%. There was a significant decline in mortality from a peak of 4.7% in 1997 to 1.1% in 2003 (p = 0.014). This was despite increasing severity of illness (as evidenced by an increasing predicted risk of death derived from the APACHE II score) over the 8-year period (p = 0.002). Conclusions: There has been a significant decline in the incidence of asthma requiring ICU admission between 1996 and 2003 among units sampled by the Australian and New Zealand Intensive Care Society Adult Patient Database. The mortality of these patients has also decreased over time and is lower than reported in other studies.