Risk prediction models: recalibration.
Explore the source record for details and available documents.
Calibration↗
Biomedical subjects
David A Harrison
Publications and source records attributed to David A Harrison.
Identification and characterisation of the high-risk surgical population in the United Kingdom.
INTRODUCTION: Little is known about mortality rates following general surgical procedures in the United Kingdom. Deaths are most common in the 'high-risk' surgical population consisting mainly of older patients, with coexisting medical disease, who undergo major surgery. Only limited data are presently available to describe this population. The aim of the present study was to estimate the size of the high-risk general surgical population and to describe the outcome and intensive care unit (ICU) resource use. METHODS: Data on inpatient general surgical procedures and ICU admissions in 94 National Health Service hospitals between January 1999 and October 2004 were extracted from the Intensive Care National Audit & Research Centre database and the CHKS database. High-risk surgical procedures were defined prospectively as those for which the mortality rate was 5% or greater. RESULTS: There were 4,117,727 surgical procedures; 2,893,432 were elective (12,704 deaths; 0.44%) and 1,224,295 were emergencies (65,674 deaths; 5.4%). A high-risk population of 513,924 patients was identified (63,340 deaths; 12.3%), which accounted for 83.8% of deaths but for only 12.5% of procedures. This population had a prolonged hospital stay (median, 16 days; interquartile range, 9-29 days). There were 59,424 ICU admissions (11,398 deaths; 19%). Among admissions directly to the ICU following surgery, there were 31,633 elective admissions with 3,199 deaths (10.1%) and 24,764 emergency admissions with 7,084 deaths (28.6%). The ICU stays were short (median, 1.6 days; interquartile range, 0.8-3.7 days) but hospital admissions for those admitted to the ICU were prolonged (median, 16 days; interquartile range, 10-30 days). Among the ICU population, 40.8% of deaths occurred after the initial discharge from the ICU. The highest mortality rate (39%) occurred in the population admitted to the ICU following initial postoperative care on a standard ward. CONCLUSION: A large high-risk surgical population accounts for 12.5% of surgical procedures but for more than 80% of deaths. Despite high mortality rates, fewer than 15% of these patients are admitted to the ICU.
Adult↗
You can take it with you: individual differences and expatriate effectiveness.
The authors report the collaborative efforts of 2 research teams that independently investigated the effects of stable personality traits (the Big Five) and specific behavioral competencies (cultural flexibility, task and people orientations, and ethnocentrism) on key dimensions of expatriate effectiveness: psychological adjustment, assignment withdrawal cognitions, and job performance. Analyses of multiple-source and longitudinal data from 3 studies, including a diverse sample of expatriates in Hong Kong and separate samples of Korean and Japanese expatriates posted around the world, indicate several direct effects of individual differences. Further data show reliable distinctions between the traits and competencies as well as incremental prediction by either set of predictors in the presence of the others.
Adaptation, Psychological↗
Understanding attitudes toward affirmative action programs in employment: summary and meta-analysis of 35 years of research.
Affirmative action programs (AAPs) are controversial employment policies in the United States and elsewhere. A large body of evidence about attitudinal reactions to AAPs in employment has accumulated over 35 years: at least 126 independent samples involving 29,000 people. However, findings are not firmly established or integrated. In the current article, the authors summarize and meta-analytically estimate relationships of AAP attitudes with (a) structural features of such programs, (b) perceiver demographic and psychological characteristics, (c) interactions of structural features with perceiver characteristics, and (d) presentation of AAP details to perceivers, including justification of the AAP. Results are generally consistent with predictions derived from self-interest considerations, organizational justice theory, and racism theories. They also suggest practical ways in which AAPs might be designed and communicated to employees to reduce attitudinal resistance.
Attitude↗
Withholding inputs in team contexts: member composition, interaction processes, evaluation structure, and social loafing.
Social loafing was observed as a naturally occurring process in project teams of students working together for 3-4 months. The authors assessed the contributions that member composition (i.e., relational dissimilarity and knowledge, skills, and abilities; KSAs), perceptions of the team's interaction processes (i.e., dispensability and the fairness of the decision-making procedures), and the team's evaluation structure (i.e., identifiability) make toward understanding loafing behavior. Identifiability moderated the impact of dispensability on loafing but not the impact of fairness on loafing. Perceptions of fairness were negatively related to the extent that participants loafed within their team. Specific aspects of relational dissimilarity were positively associated with perceptions of dispensability and negatively associated with perceptions of fairness, whereas KSAs were negatively associated with perceptions of dispensability.
Adolescent↗
Recalibration of risk prediction models in a large multicenter cohort of admissions to adult, general critical care units in the United Kingdom.
OBJECTIVE: To assess the performance of published risk prediction models in common use in adult critical care in the United Kingdom and to recalibrate these models in a large representative database of critical care admissions. DESIGN: Prospective cohort study. SETTING: A total of 163 adult general critical care units in England, Wales, and Northern Ireland, during the period of December 1995 to August 2003. PATIENTS: A total of 231,930 admissions, of which 141,106 met inclusion criteria and had sufficient data recorded for all risk prediction models. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The published versions of the Acute Physiology and Chronic Health Evaluation (APACHE) II, APACHE II UK, APACHE III, Simplified Acute Physiology Score (SAPS) II, and Mortality Probability Models (MPM) II were evaluated for discrimination and calibration by means of a combination of appropriate statistical measures recommended by an expert steering committee. All models showed good discrimination (the c index varied from 0.803 to 0.832) but imperfect calibration. Recalibration of the models, which was performed by both the Cox method and re-estimating coefficients, led to improved discrimination and calibration, although all models still showed significant departures from perfect calibration. CONCLUSIONS: Risk prediction models developed in another country require validation and recalibration before being used to provide risk-adjusted outcomes within a new country setting. Periodic reassessment is beneficial to ensure calibration is maintained.
APACHE↗
The epidemiology of severe sepsis in England, Wales and Northern Ireland, 1996 to 2004: secondary analysis of a high quality clinical database, the ICNARC Case Mix Programme Database.
INTRODUCTION: To evaluate the impact of recent evidence-based treatments for severe sepsis in routine clinical care requires an understanding of the underlying epidemiology, particularly with regard to trends over time. We interrogated a high quality clinical database to examine trends in the incidence and mortality of severe sepsis over a nine-year period. METHODS: Admissions with severe sepsis occurring at any time within 24 hours of admission to critical care were identified to an established methodology using raw physiological data from the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, containing data from 343,860 admissions to 172 adult, general critical care units in England, Wales and Northern Ireland between December 1995 and January 2005. Generalised linear models were used to assess changes in the incidence, case mix, outcomes and activity of these admissions. RESULTS: In total, 92,672 admissions (27.0%) were identified as having severe sepsis in the first 24 hours following admission. The percentage of admissions with severe sepsis during the first 24 hours rose from 23.5% in 1996 to 28.7% in 2004. This represents an increase from an estimated 18,500 to 31,000 admissions to all 240 adult, general critical care units in England, Wales and Northern Ireland. Hospital mortality for admissions with severe sepsis decreased from 48.3% in 1996 to 44.7% in 2004, but the total number of deaths increased from an estimated 9,000 to 14,000. The treated incidence of severe sepsis per 100,000 population rose from 46 in 1996 to 66 in 2003, with the associated number of hospital deaths per 100,000 population rising from 23 to 30. CONCLUSION: The population incidence of critical care admission with severe sepsis during the first 24 hours and associated hospital deaths are increasing. These baseline data provide essential information to those wishing to evaluate the introduction of the Surviving Sepsis Campaign care bundles in UK hospitals.
Databases, Factual↗
Community-acquired pneumonia on the intensive care unit: secondary analysis of 17,869 cases in the ICNARC Case Mix Programme Database.
INTRODUCTION: This paper describes the case mix, outcome and activity for admissions to intensive care units (ICUs) with community-acquired pneumonia (CAP). METHODS: We conducted a secondary analysis of a high quality clinical database, the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, of 301,871 admissions to 172 adult ICUs across England, Wales and Northern Ireland, 1995 to 2004. Cases of CAP were identified from pneumonia admissions excluding nosocomial pneumonias and the immuno-compromised. It was not possible to review data from the time of hospital admission; therefore, some patients who developed hospital-acquired/nosocomial pneumonia may have been included. RESULTS: We identified 17,869 cases of CAP (5.9% of all ICU admissions). There was a 128% increase in admissions for CAP from 12.8 per unit to 29.2 per unit during the study period compared to only a 24% rise in total ICU admissions (p < 0.001). Eighty-five percent of admissions were from within the same hospital. Fifty-nine percent of cases were admitted to the ICU < 2 days, 21.5% between 2 and 7 days, and 19.5% > 7 days after hospital admission. Between 1995 and 1999 and 2000 and 2004 there was a rise in admissions from accident and emergency (14.8% to 16.8%; p < 0.001) and high dependency units (6.9% to 11.9%; p < 0.001) within the same hospital, those aged > 74 (18.5 to 26.1%; p < 0.001), and mean APACHE II score (6.83 to 6.91; p < 0.001). There was a fall in past history of severe respiratory problems (8.7% to 6.4%; p < 0.001), renal replacement therapy (1.6% to 1.2%; p < 0.01), steroid treatment (3.4% to 2.8%; p < 0.05), sedation/paralysis (50.2% to 40.4%; p < 0.001), cardiopulmonary resuscitation prior to admission (7.5% to 5.5%; p < 0.001), and septic shock (7.3% to 6.6%; p < 0.001). ICU mortality was 34.9% and ultimate hospital mortality 49.4%. Mortality was 46.3% in those admitted to the ICU within 2 days of hospital admission rising to 50.4% in those admitted at 2 to 7 days and 57.6% in those admitted after 7 days following hospital admission. CONCLUSION: CAP makes up a small, but important and rising, proportion of adult ICU admissions. Survival of over half of all cases vindicates the use of ICU facilities in CAP management. Nevertheless, overall mortality remains high, especially in those admitted later in their hospital stay.
Adolescent↗
End-of-life decisions: a cohort study of the withdrawal of all active treatment in intensive care units in the United Kingdom.
OBJECTIVE: To describe the epidemiology of active treatment withdrawal in a nationally representative cohort of intensive care units (ICUs) focusing on between-unit differences. DESIGN AND SETTING: Cohort study in 127 adult general ICUs in England, Wales and Northern Ireland, 1995 to 2001. PATIENTS: 118,199 adult admissions to ICUs. MEASUREMENTS AND RESULTS: The decision to withdraw all active treatment was made for 11,694 of 118,199 patients (9.9%). There were a total of 36,397 deaths (30.8%) before discharge from hospital, and 11,586 (31.8%) of these occurred after the decision to withdraw active treatment, with no change over time (p=0.54). Considerable variation existed between units regarding the percentage of ICU deaths that occurred after the decision to withdraw active treatment (1.7-96.1%). Median time to death after the decision to withdraw active treatment was 2.4 h; 8% survived more than 24 h. After multilevel modelling, the factors independently associated with the decision to withdraw active treatment were: older age, pre-existing severe medical conditions, emergency surgery or medical admission, cardiopulmonary resuscitation in the 24 h prior to admission, and ventilation or sedation/paralysis in the first 24 h after admission. Substantial between unit variability remained after accounting for case-mix differences in admissions. CONCLUSIONS: Although we were unable to examine partial withdrawal or withholding of care in this study, we found that the withdrawal of all active treatment is widespread in ICUs in the United Kingdom. There was little change in this practice over the period examined. However, there was considerable variation by unit, even after accounting for patient factors and differences in size and type of ICU, suggesting improved guidelines may be useful to facilitate uniform decision making.
Adolescent↗
Health services research in critical care using administrative data.
The aim of health services research is to provide unbiased, scientific evidence to influence health services policy at all levels. Secondary analysis of administrative data can be employed for the purpose of evaluating questions relevant to health services research in the field of critical care. This article provides an overview of the topic and specifically reviews the key components to evaluating and performing research in critical care using administrative data, including how to evaluate the quality of administrative data itself, and also how to evaluate the quality of studies that employ administrative data. The article concludes with a step-wise approach to conducting studies of critical care based on administrative data.
Critical Care↗
Winter excess mortality in intensive care in the UK: an analysis of outcome adjusted for patient case mix and unit workload.
OBJECTIVE: To investigate whether mortality in UK intensive care units is higher in winter than in non-winter and to explore the importance of variations in case mix and increased pressure on ICUs. DESIGN AND SETTING: Cohort study in 115 adult, general ICUs in England, Wales and Northern Ireland. PATIENTS AND PARTICIPANTS: 113,389 admissions from 1995 to 2000. MEASUREMENTS AND RESULTS: Hospital mortality following admission to ICU was compared between winter (December-February) and non-winter (March-November). The causes of any observed differences were explored by adjusting for the case mix of admissions and the workload of the ICUs. Crude hospital mortality was higher in winter. After adjusting for case mix using the APACHE II mortality probability this effect was reduced but still significant. When additional factors reflecting case mix and workload were introduced into the model, the overall effect of winter admission was no longer significant. Factors reflecting both the case mix of the individual patient and of the patients in surrounding beds were found to be significantly associated with outcome. After adjustment for other factors, the occupancy of the unit (proportion of beds occupied) was not significantly associated with mortality. CONCLUSIONS: The excess winter mortality observed in UK ICUs can be explained by variation in the case mix of admissions. Unit occupancy was not associated with mortality.
APACHE↗
Characteristics and outcome for admissions to adult, general critical care units with acute severe asthma: a secondary analysis of the ICNARC Case Mix Programme Database.
INTRODUCTION: This report describes the case mix, outcome and activity (duration of intensive care unit [ICU] and hospital stay, inter-hospital transfer, and readmissions to the ICU) for admissions to ICUs for acute severe asthma, and investigates the effect of case mix factors on outcome. METHODS: We conducted a secondary analysis of data from a high-quality clinical database (the Intensive Care National Audit and Research Centre [ICNARC] Case Mix Programme Database) of 129,647 admissions to 128 adult, general critical care units across England, Wales and Northern Ireland over the period 1995-2001. RESULTS: Asthma accounted for 2152 (1.7%) admissions, and in 57% mechanical ventilation was employed during the first 24 hours in the ICU. A total of 147 (7.1%) patients died in intensive care and 199 (9.8%) died before discharge from hospital. The mean age was 43.6 years, and the ratio of women to men was 2:1. Median length of stay was 1.5 days in the ICU and 8 days in hospital. Older age, female sex, having received cardiopulmonary resuscitation (CPR) within 24 hours before admission, having suffered a neurological insult during the first 24 hours in the ICU, higher heart rate, and hypercapnia were associated with greater risk for in-hospital death after adjusting for Acute Physiology and Chronic Health Evaluation II score. CPR before admission, neurological insult, hypoxaemia and hypercapnia were associated with receipt of mechanical ventilation after adjusting for Acute Physiology and Chronic Health Evaluation II score. CONCLUSION: ICU admission for asthma is relatively uncommon but remains associated with appreciable in-hospital mortality. The greatest determinant of poor hospital survival in asthma patients was receipt of CPR within 24 hours before admission to ICU. Clinical management of these patients should be directed at preventing cardiac arrest before admission.
APACHE↗
Case mix, outcome and length of stay for admissions to adult, general critical care units in England, Wales and Northern Ireland: the Intensive Care National Audit & Research Centre Case Mix Programme Database.
INTRODUCTION: The present paper describes the methods of data collection and validation employed in the Intensive Care National Audit & Research Centre Case Mix Programme (CMP), a national comparative audit of outcome for adult, critical care admissions. The paper also describes the case mix, outcome and activity of the admissions in the Case Mix Programme Database (CMPD). METHODS: The CMP collects data on consecutive admissions to adult, general critical care units in England, Wales and Northern Ireland. Explicit steps are taken to ensure the accuracy of the data, including use of a dataset specification, of initial and refresher training courses, and of local and central validation of submitted data for incomplete, illogical and inconsistent values. Criteria for evaluating clinical databases developed by the Directory of Clinical Databases were applied to the CMPD. The case mix, outcome and activity for all admissions were briefly summarised. RESULTS: The mean quality level achieved by the CMPD for the 10 Directory of Clinical Databases criteria was 3.4 (on a scale of 1 = worst to 4 = best). The CMPD contained validated data on 129,647 admissions to 128 units. The median age was 63 years, and 59% were male. The mean Acute Physiology and Chronic Health Evaluation II score was 16.5. Mortality was 20.3% in the CMP unit and was 30.8% at ultimate discharge from hospital. Nonsurvivors stayed longer in intensive care than did survivors (median 2.0 days versus 1.7 days in the CMP unit) but had a shorter total hospital length of stay (9 days versus 16 days). Results for the CMPD were comparable with results from other published reports of UK critical care admissions. CONCLUSIONS: The CMP uses rigorous methods to ensure data are complete, valid and reliable. The CMP scores well against published criteria for high-quality clinical databases.
Adult↗
Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial.
BACKGROUND: Over the past 30 years the pulmonary artery catheter (PAC) has become a widely used haemodynamic monitoring device in the management of critically ill patients, though doubts exist about its safety. Our aim was, therefore, to ascertain whether hospital mortality is reduced in critically ill patients when they are managed with a PAC. METHODS: We did a randomised controlled trial to which we enrolled 1041 patients from 65 UK intensive care units. We assigned individuals to management with (n=519) or without (n=522) a PAC. The timing of insertion and subsequent clinical management were at the discretion of the treating clinician. Intensive care units decided a priori to have the option of using an alternative cardiac output-monitoring device in control patients. FINDINGS: 1014 patients were eligible for analysis. We noted no difference in hospital mortality between patients managed with or without a PAC (68% [346 of 506] vs 66% [333 of 507], p=0.39; adjusted hazard ratio 1.09, 95% CI 0.94-1.27). We noted complications associated with insertion of a PAC in 46 of 486 individuals in whom the device was placed, none of which was fatal. INTERPRETATION: Our findings indicate no clear evidence of benefit or harm by managing critically ill patients with a PAC. Efficacy studies are needed to ascertain whether management protocols involving PAC use can result in improved outcomes in specific groups if these devices are not to become a redundant technology.
Adolescent↗