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Jack E Zimmerman

Publications and source records attributed to Jack E Zimmerman.

7 recordsLinked to original sources
PubMed2006

Acute Physiology and Chronic Health Evaluation (APACHE) IV: hospital mortality assessment for today's critically ill patients.

OBJECTIVE: To improve the accuracy of the Acute Physiology and Chronic Health Evaluation (APACHE) method for predicting hospital mortality among critically ill adults and to evaluate changes in the accuracy of earlier APACHE models. DESIGN: : Observational cohort study. SETTING: A total of 104 intensive care units (ICUs) in 45 U.S. hospitals. PATIENTS: A total of 131,618 consecutive ICU admissions during 2002 and 2003, of which 110,558 met inclusion criteria and had complete data. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We developed APACHE IV using ICU day 1 information and a multivariate logistic regression procedure to estimate the probability of hospital death for randomly selected patients who comprised 60% of the database. Predictor variables were similar to those in APACHE III, but new variables were added and different statistical modeling used. We assessed the accuracy of APACHE IV predictions by comparing observed and predicted hospital mortality for the excluded patients (validation set). We tested discrimination and used multiple tests of calibration in aggregate and for patient subgroups. APACHE IV had good discrimination (area under the receiver operating characteristic curve = 0.88) and calibration (Hosmer-Lemeshow C statistic = 16.9, p = .08). For 90% of 116 ICU admission diagnoses, the ratio of observed to predicted mortality was not significantly different from 1.0. We also used the validation data set to compare the accuracy of APACHE IV predictions to those using APACHE III versions developed 7 and 14 yrs previously. There was little change in discrimination, but aggregate mortality was systematically overestimated as model age increased. When examined across disease, predictive accuracy was maintained for some diagnoses but for others seemed to reflect changes in practice or therapy. CONCLUSIONS: APACHE IV predictions of hospital mortality have good discrimination and calibration and should be useful for benchmarking performance in U.S. ICUs. The accuracy of predictive models is dynamic and should be periodically retested. When accuracy deteriorates they should be revised and updated.

APACHE↗
PubMed2006

Intensive care unit length of stay: Benchmarking based on Acute Physiology and Chronic Health Evaluation (APACHE) IV.

OBJECTIVE: To revise and update the Acute Physiology and Chronic Health Evaluation (APACHE) model for predicting intensive care unit (ICU) length of stay. DESIGN: Observational cohort study. SETTING: One hundred and four ICUs in 45 U.S. hospitals. PATIENTS: Patients included 131,618 consecutive ICU admissions during 2002 and 2003, of which 116,209 met inclusion criteria. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The APACHE IV model for predicting ICU length of stay was developed using ICU day 1 patient data and a multivariate linear regression procedure to estimate the precise ICU stay for randomly selected patients who comprised 60% of the database. New variables were added to the previous APACHE III model, and advanced statistical modeling techniques were used. Accuracy was assessed by comparing mean observed and mean predicted ICU stay for the excluded 40% of patients. Aggregate mean observed ICU stay was 3.86 days and mean predicted 3.78 days (p < .001), a difference of 1.9 hrs. For 108 (93%) of 116 diagnoses, there was no significant difference between mean observed and mean predicted ICU stay. The model accounted for 21.5% of the variation in ICU stay across individual patients and 62% across ICUs. Correspondence between mean observed and mean predicted length of stay was reduced for patients with a short (< or =1.7 days) or long (> or =9.4 days) ICU stay and a low (<20%) or high (>80%) risk of death on ICU day 1. CONCLUSIONS: The APACHE IV model provides clinically useful ICU length of stay predictions for critically ill patient groups, but its accuracy and utility are limited for individual patients. APACHE IV benchmarks for ICU stay are useful for assessing the efficiency of unit throughput and support examination of structural, managerial, and patient factors that affect ICU stay.

APACHE↗
PubMed2003

The use of benchmarking to identify top performing critical care units: a preliminary assessment of their policies and practices.

PURPOSE: To describe the policies and practices of intensive care units (ICUs) with good patient survival and highly efficient resource use and to identify relevant variables for future investigation. MATERIALS AND METHODS: We used clinical data for 359,715 patients from 108 ICUs to compare the ratios of actual with Acute Physiology and Chronic Health Evaluation (APACHE) III predicted hospital mortality, ICU and hospital stay, and the proportion of low-risk monitor patients. The best performing ICUs (top 10%) were defined by a mortality ratio of 1.0 or less, and either the lowest ratio for ICU stay, hospital stay, or percentage of low-risk monitor patients. The medical and nursing directors of top performing ICUs completed a questionnaire to describe their unit's structure policies and practices. RESULTS: Among the 108 ICUs, 61 (56%) had a ratio of actual to predicted hospital mortality of 1.0 or less and the best performing units had ICU stay ratios of 0.62 to 0.79, hospital stay ratios of 0.73 to 0.77, and admitted 10% to 38% low-risk monitor patients. ICU structure varied among the best performing ICUs. Units with the shortest ICU and hospital stay had alternatives to intensive care, methods to facilitate patient throughput, used multiple protocols for high-volume diagnoses and care processes, and continuously monitored resource use. Units with the fewest low-risk monitor patients screened potential admissions, had intermediate care areas, extended-stay recovery rooms, and care pathways for high-volume diagnoses. CONCLUSIONS: Benchmarking can be used to identify ICUs with good patient survival and highly efficient resource use. The combination of policies and practices used by these units might improve resource use in other ICUs.

APACHE↗
PubMed2002

A multicenter description of intermediate-care patients: comparison with ICU low-risk monitor patients.

STUDY OBJECTIVES: To describe the characteristics and outcomes of patients admitted to intermediate-care areas (ICAs) and to compare them with those of ICU patients who receive monitoring only on day 1 and are at a low risk (i.e., < 10%) for receiving subsequent active life-supporting therapy (i.e., low-risk monitor patients). DESIGN: Nonrandomized, retrospective, cohort study. SETTING: Thirteen US teaching hospitals and 19 nonteaching hospitals. PATIENTS: A consecutive sample of 8,971 patients at 37 ICAs and 5,116 low-risk (i.e., < 10%) monitor patients at 59 ICUs in 32 US hospitals. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: We recorded demographic and clinical characteristics, resource use, and outcomes for the ICA and ICU low-risk monitor patients. Patient data and outcomes for this study were collected concurrently or retrospectively. ICA and ICU low-risk monitor patients were similar in regard to gender, race, and frequency of comorbitities, but ICA patients were significantly (p < 0.001) older, had fewer physiologic abnormalities (mean acute physiology score, 16.7 vs 19.8, respectively), and were more frequently admitted due to nonoperative diagnoses. The mean length of stay for ICA patients was significantly longer (3.9 days) than for ICU low-risk monitor patients (2.6 days; p < 0.001). The hospital mortality rate was significantly higher for ICA patients (3.1%) compared to ICU low-risk monitor patients (2.3%; p = 0.002). CONCLUSIONS: The clinical features of ICA patients are similar, but not identical to, those of less severely ill ICU monitor patients. Comparisons of hospital death rates and lengths of stay for these patients should be adjusted for characteristics that previously have been shown to influence these outcomes.

APACHE↗