Utilization of small changes in serum creatinine with clinical risk factors to assess the risk of AKI in critically lll adults.

BACKGROUND AND OBJECTIVES: Disease biomarkers require appropriate clinical context to be used effectively. Combining clinical risk factors, in addition to small changes in serum creatinine, has been proposed to improve the assessment of AKI. This notion was developed in order to identify the risk of AKI early in a patient's clinical course. We set out to assess the performance of this combination approach. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A secondary analysis of data from a prospective multicenter intensive care unit cohort study (September 2009 to April 2010) was performed. Patients at high risk using this combination approach were defined as an early increase in serum creatinine of 0.1-0.4 mg/dl, depending on number of clinical factors predisposing to AKI. AKI was defined and staged using the Acute Kidney Injury Network criteria. The primary outcome was evolution to severe AKI (Acute Kidney Injury Network stages 2 and 3) within 7 days in the intensive care unit. RESULTS: Of 506 patients, 214 (42.2%) patients had early creatinine elevation and were deemed at high risk for AKI. This group was more likely to subsequently develop the primary endpoint (16.4% versus 1.0% [not at high risk], P<0.001). The sensitivity of this grouping for severe AKI was 92%, the specificity was 62%, the positive predictive value was 16%, and the negative predictive value was 99%. After adjustment for Sequential Organ Failure Assessment score, serum creatinine, and hazard tier for AKI, early creatinine elevation remained an independent predictor for severe AKI (adjusted relative risk, 12.86; 95% confidence interval, 3.52 to 46.97). Addition of early creatinine elevation to the best clinical model improved prediction of the primary outcome (area under the receiver operating characteristic curve increased from 0.75 to 0.83, P<0.001). CONCLUSION: Critically ill patients at high AKI risk, based on the combination of clinical factors and early creatinine elevation, are significantly more likely to develop severe AKI. As initially hypothesized, the high-risk combination group methodology can be used to identify patients at low risk for severe AKI in whom AKI biomarker testing may be expected to have low yield. The high risk combination group methodology could potentially allow clinicians to optimize biomarker use.

Determinants of prolonged intensive care unit stay after cardiac surgery in the elderly.

OBJECTIVES: In the last decade, there has been a rapid increase in the number of elderly patients referred for cardiac surgery. Recent studies have identified risk factors for prolonged intensive care unit (ICU) stay in cardiac surgery patients. The aims of this study was to evaluate pre-operative risk factors for ICU stay longer than 3 days in a cardiac surgery elderly population, and whether prolonged ICU stay may influence disability, functional recovery and length of rehabilitation. METHODS: Two hundred and fifty elderly (≥65 years) cardiac surgery patients were consecutively evaluated at enter in cardiac rehabilitation after ICU dismissal from January 2008 to July 2009. Univariate and multivariate analyses for risk factors were performed for ICU stay longer than 3 days. Thereafter, 6-minute walking test (6MWT), Barthel Index (BI), BI percent recovery and length of stay (LOS) in rehabilitation were evaluated. RESULTS: Mean age was 72.9±4.8 yrs, 170 (68%) patients underwent cardiac surgery for coronary artery by-pass grafting (CABG), 56 (22.4%) for valve replacement and 24 (9.6%) for both CABG and valve replacement. Mean ICU stay was 1.9±1.5 days and 72 patients (28.8%) spent more than 3 days in ICU. Age, New York Heart Association class ≥3, Cumulative Illness Rating Scale (CIRS) score, prevalence of stroke and renal failure were significantly higher in patients with than in those without ICU stay ≥3 days. Off-pump CABG, Physical Activity Scale for the Elderly (PASE), BI and 6MWT were significantly lower in patients with than in those without ICU stay ≥3 days. Multivariate analysis shows that female sex, a NYHA class ≥3, CIRS and PASE score are predictors of ICU stay ≥3 days independently of age, off-pump CABG, stroke and renal failure. Multiple linear regression shows that ICU stay ≥3 days is negatively associated with 6MWT, BI at entry and BI percent recovery, whereas it is positively associated with a longer rehabilitation LOS. CONCLUSIONS: Pre-operative comprehensive assessment in the elderly could help to identify predictors of long ICU stay after cardiac surgery. This approach could help to better define the elderly cardiac surgery patients and their needs throughout the cardiac rehabilitation program in order to maximize functional capacity recovery, reducing disability and rehabilitation LOS.

RIFLE-based data collection/management system applied to a prospective cohort multicenter Italian study on the epidemiology of acute kidney injury in the intensive care unit.

The epidemiology of acute kidney injury (AKI) has been difficult to explore in the past, due to different definitions across various studies. Nevertheless, this is a very important topic today in light of the high morbidity and mortality of critically ill patients presenting renal dysfunction during their stay in the intensive care unit (ICU). The case mix has changed over the years, and AKI is a common problem in critically ill patients often requiring renal replacement therapy (RRT). The RIFLE and AKIN initiatives have provided a unifying definition for AKI, making possible large retrospective studies in different countries. The present study aims at validating a unified web-based data collection and data management tool based on the most recent AKI definition/classification system. The interactive database is designed to elucidate the epidemiology of AKI in a critically ill population. As a test, we performed a prospective observational multicenter study designed to prospectively evaluate all incident admissions in ten ICUs in Italy and the relevant epidemiology of AKI. Thus, a simple user-friendly web-based data collection tool was created with the scope to serve for this study and to facilitate future multicenter collaborative efforts. We enrolled 601 consecutive incident patients into the study; 25 patients with end-stage renal disease were excluded, leaving 576 patients for analysis. The median age was 66 (IQR 53-76) years, 59.4% were male, while median Simplified Acute Physiology Score II and Acute Physiology and Chronic Health Evaluation II scores were 43 (IQR 35-54) and 18 (IQR 13-24), respectively. The most common diagnostic categories for ICU admission were: respiratory (27.4%), followed by neurologic (17%), trauma (14.4%), and cardiovascular (12.1%). Crude ICU and hospital mortality were 21.7% and median ICU length of stay was 5 (IQR 3-14) days. Of 576 patients, 246 patients (42.7%) had AKI within 24 h of ICU admission, while 133 developed new AKI later during their ICU stay. RIFLE-initial class was Risk in 205 patients (54.1%), Injury in 99 (26.1%) and Failure in 75 (19.8%). Progression of AKI to a worse RIFLE class was seen in 114 patients (30.8% of AKI patients). AKI patients were older, with higher frequency of common risk factors. 116 AKI patients (30.6%) fulfilled criteria for sepsis during their ICU stay, compared to 33 (16.7%) of non-AKI patients (p < 0.001). 48 patients (8.3%) were treated with RRT in the ICU. Patients were started on RRT a median of 2 (IQR 0-6) days after ICU admission. AKI patients were started on RRT a median of 1 (IQR 0-4) day after fulfilling criteria for AKI. Median duration of RRT was 5 (IQR 2-10) days. AKI patients had a higher crude ICU mortality (28.8 vs. 8.1%, non-AKI; p < 0.001) and longer ICU length of stay (median 7 vs. 3 days, non-AKI; p < 0.001). Crude ICU mortality and ICU length of stay increased with greater severity of AKI. 225 (59.4% of AKI patients) had complete recovery of renal function, with a serum creatinine at time of ICU discharge which was ≤120% of baseline; an additional 51 AKI patients (13.5%) had partial renal recovery, while 103 (27.2%) had not recovered renal function at the time of death or ICU discharge. The study supports the use of RIFLE as an optimal classification system to stage AKI severity. AKI is indeed a deadly complication for ICU patients, where the level of severity is correlated with mortality and length of stay. The tool developed for data collection was user-friendly and easy to implement. Some of its features, including a RIFLE class alert system, may help the treating physician to systematically collect AKI data in the ICU and possibly may guide specific decisions on the institution of RRT.