***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objective : To revise and up date 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 r and omly selected patients who comprised 60 % of the data base . 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 ( ≤1.7 days ) or long ( ≥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 clinical ly 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 Purpose : To evaluate the influence of malignancy on the decision to limit life-sustaining therapy in the intensive care unit ( ICU ) . Methods : At the day of patients ’ admission to the ICU , we prospect ively collected information on demographics , acute physiology and chronic health evaluation ( APACHE ) II score , and features related to malignancy . We retrospectively collected information on in-hospital survival and decision to withhold or withdraw life-sustaining treatment .  Results : This study included 122 adult critically ill patients . After adjusting for age and APACHE II score , patients with malignancy had 3.02 ( 95 % CI 1.19 to 7.62 ) higher odds of having life-sustaining therapy withdrawn or withheld as compared to patients without active malignancy . Conclusion : Our study showed that critically ill patients with malignancy are more likely to have their life-sustaining therapy withheld or withdrawn than those without malignancy after adjusting for severity of disease . This finding may be related to a perception that critically ill patients with malignancy have worse prognosis as compared with those without malignancy OBJECTIVE To determine if racial and ethnic variations exist in  intensive care ( ICU ) use during terminal hospitalizations , and , if variations do exist , to determine whether they can be explained by systematic differences in hospital utilization by race/ethnicity . DATA SOURCE 1999 hospital discharge data from all nonfederal hospitals in Florida , Massachusetts , New Jersey , New York , and Virginia . DESIGN We identified all terminal admissions ( N = 192,705 ) among adults . We calculated crude rates of ICU use  among non-Hispanic whites , blacks , Hispanics , and those with " other " race/ethnicity . We performed multivariable logistic regression on ICU use , with and without adjustment for clustering of patients within hospitals , to calculate adjusted differences in ICU use and by race/ethnicity . We explored both a r and om-effects ( RE ) and fixed-effect ( FE ) specification to adjust for hospital-level clustering . DATA COLLECTION The data were collected by each state . PRINCIPAL FINDINGS ICU use during the terminal hospitalization was highest among nonwhites , varying from 64.4 percent among Hispanics to 57.5 percent among whites . Compared to white women , the risk-adjusted odds of ICU use was higher for white men and for nonwhites of both sexes ( odds ratios [ ORs ] and 95 percent confidence intervals : white men = 1.16 ( 1.14 - 1.19 ) , black men = 1.35 ( 1.17 - 1.56 ) , Hispanic men = 1.52 ( 1.27 - 1.82 ) , black women = 1.31 ( 1.25 - 1.37 ) , Hispanic women = 1.53 ( 1.43 - 1.63 ) ) . Additional adjustment for within-hospital clustering of patients using the RE model did not change the estimate for white men , but markedly attenuated observed differences for blacks ( OR for men = 1.12 ( 0.96 - 1.31 ) , women = 1.10 ( 1.03 - 1.17 ) ) and Hispanics ( OR for men = 1.19 ( 1.00 - 1.42 ) , women = 1.18 ( 1.09 - 1.27 ) ) . Results from the FE model were similar to the RE model ( OR for black men = 1.10 ( 0.95 - 1.28 ) , black women = 1.07 ( 1.02 - 1.13 ) Hispanic men = 1.17 ( 0.96 - 1.42 ) , and Hispanic women = 1.14 ( 1.06 - 1.24 ) ) CONCLUSIONS The majority of observed differences in terminal ICU use among blacks and Hispanics were attributable to their use of hospitals with higher ICU use rather than to racial differences in ICU use within the same hospital Context In the United States , what happens to incapacitated patients who lack surrogate decision makers  has not been quantified . Contribution This prospect i ve study of 3011 critically ill adults in 7 academically affiliated , geographically diverse intensive care units found that 5.5 % of the deaths occurred in patients who lacked a surrogate decision maker and an advance directive . Physicians and unit teams made life-support decisions without a formal hospital or court review for 30 of 37 such patients . Pertinent policies varied widely across hospitals and states . Caution Physicians self-reported information about decision making . Implication Physicians commonly make life-support decisions for patients who lack surrogate decision makers , without formal institutional or judicial review . The Editors The vast majority of deaths in intensive care units are preceded by a decision to limit life support ( 1 , 2 ) . Most critically ill patients can not participate in these decisions ( 1 , 3 ) . Consequently , the patients ' families generally function as surrogate decision makers ( 4 ) . However , some patients who lack decision-making capacity do not have a surrogate and have not completed an advance directive . Difficulties in making decisions for this patient population have been documented in skilled-nursing facilities ( 5 , 6 ) , general hospital wards ( 7 ) , and intensive care units of 1 major medical center ( 810 ) . These cases raise ethical and legal questions about who should make decisions for such patients and under what circumstances it is permissible to limit life-sustaining treatment . Although one third of physicians who care for critically ill patients have withdrawn life support in at least 1 patient who lacked decision-making capacity , a surrogate , and an advance directive , little is known about how frequently such decisions are made in intensive care units ( 11 ) . Professional organization guidelines differ on how decisions should be made for these patients . The American Medical Association ( AMA ) recommends ethics committee or judicial review , the American College of Physicians ( ACP ) recommends judicial review , and the American Geriatrics Society ( AGS ) advises against routine court involvement but recommends that decisions be made by clinicians caring for the patient ( 1214 ) . It is unknown what effect these recommendations have had on actual treatment decisions for incapacitated patients who lack a surrogate and an advance directive . Moreover , little is known about how decisions to limit life support are made for these patients . Therefore , we conducted a multicenter , prospect i ve study to determine the proportion of deaths in intensive care units that occur in patients who lack decision-making capacity , a surrogate , and an advance directive  and how decisions regarding life support are made for such patients . Methods Design , Patients , and Setting This multicenter , prospect i ve cohort study included all adults who were admitted to the medical or medical-surgical intensive care units of 7 hospitals in a 6-month period during 2004 to 2005 . The hospitals are located in California , Oregon , Washington , Pennsylvania , New York , and New Hampshire . Most of the study hospitals are located in metropolitan areas , and all have an academic affiliation . Several are county hospitals , and all are tertiary care centers . The number of beds in the intensive care units ranged from 8 to 16 . Other details regarding the study institutions have been deleted to protect the individual institutions and physicians from legal inquiry . The institutional review board at each hospital approved the study . We contacted the attending physician twice weekly to determine whether he or she had admitted any patients who lacked decision-making capacity , a surrogate , and an advance directive and , if so , whether there had been consideration of limiting life support in that patient . Patients were eligible if they lacked decision-making capacity and both a written advance directive and a surrogate decision maker . Because some physicians might not consider limiting life support without consent of the patient or a surrogate , we also included patients for whom a physician would have considered limiting life support if a family member had been available to act as a surrogate . Patients were considered to lack decision-making capacity if the attending physician determined that they could not participate in decisions about their medical care . We used the physicians ' assessment s of decision-making capacity rather than formal cognitive testing to capture how decisions were made in clinical practice , although physicians ' assessment s of decision-making capacity correlate highly with formal cognitive testing ( 15 ) . Written advance directives were defined as a document signed by the patient that delineated any aspect of their end-of-life treatment preferences . Patients were considered to lack a surrogate decision maker if they had no family , legally appointed guardian , or health care proxy available to participate in decisions about their medical care . Initial Evaluation and Follow-up If the attending physician indicated that withholding or withdrawing life-sustaining treatment had been considered or would have been considered if a surrogate had been available , he or she completed a question naire about the decision-making process that was vali date d in a separate pilot study for this project ( 10 ) . The question naire addressed patient and physician demographic characteristics , factors that influenced the decision of whether life-sustaining treatment should be limited , persons involved in the decision-making process , and whether the patient died in the intensive care unit . The question naire is available from the first author upon request . Physicians were told that the purpose of the study was to underst and processes of care for incapacitated patients without surrogates but were not informed of the specific research questions . At the end of the 6-month study period , we used administrative records from each institution to determine the number of admissions and deaths before discharge from the intensive care unit during the study period . We obtained written hospital policies that addressed how decisions about limiting life support should be made for incapacitated patients who lack a surrogate decision maker or an advance directive . We examined the published guidelines from the major U.S. medical societies ( AMA , ACP , and AGS ) and critical care organizations ( American Thoracic Society , American College of Chest Physicians , and Society for Critical Care Medicine ) to determine whether they had a policy for decision making in this population and , if so , what the policy was . In addition , a legal scholar research ed state laws to determine if relevant laws that addressed whether it is permissible to limit life support in these patients existed and , if so , the process by which these decisions should be made . We developed a categorization of groups that might be involved in the decision-making process , including , in increasing level of oversight , other members of the intensive care unit team ( nurses , fellows , and residents ) , another attending physician , hospital review ( an ethics committee , multidisciplinary committee , or patient ombudsman ) , and judicial review ( court ruling on the decision or a court-appointed guardian ) . At the end of the study , 3 investigators ( an ethicist , a lawyer , and a critical care physician ) together adjudicated whether each decision was made in accordance with hospital policy , professional society guidelines , and state statutes or court rulings . Legal Considerations Physicians may believe that they are in legal jeopardy if they limit life-sustaining treatment in a patient who can not provide informed consent and who lacks a surrogate decision maker and an advance directive . Therefore , we took several steps to protect the identities of physicians and patients . First , we removed from our data bases all information about the study hospitals , except the state in which they are located . Second , the study was anonymous for patients and physicians . Third , to minimize the chance that study records would allow a direct link between individual physicians and specific treatment decisions , we did not perform a chart review or collect identifying information . To protect individual physicians and institutions from legal scrutiny , we present the data on decision making in aggregate form only . Finally , we obtained a federal Certificate of Confidentiality from the National Institutes of Health that protects research data from subpoena in the event of a legal inquiry ( 16 ) . The Appendix provides more information about this Certificate . Role of the Funding Sources The funding sources had no role in the design , conduct , or analysis of this study or in the decision to su bmi t the manuscript for publication . Results A total of 3011 patients were admitted to intensive care units during the study period . Table 1 shows that the combined mortality rate for all intensive care units was 15.0 
    Output:
    
Patient factors predicting less intensive end-of-life care include increasing age , comorbidity , and limited functional status ; these factors appear to be influential for both clinicians and patients .
Patient and clinician race , ethnicity , and nationality also appear to influence the technological intensity of end-of-life care .
In general , white patients and those in North America and Northern Europe may be less likely to desire intensive end-of-life care than others .
Physicians of similar geo-ethnic origin to patients appear less likely to prescribe such therapy .
Physicians with more clinical experience and those routinely working in the intensive care unit are less likely than other physicians to recommend technologically intense care for critically ill patients at the end-of-life .
CONCLUSIONS Patients and clinicians may approach end-of-life discussion s with different expectations and preferences , influenced by religion , race , culture , and geography .