Studying outcomes of intensive care unit survivors: measuring exposures and outcomes

Background Measurement of long-term outcomes and the patient and intensive care unit (ICU) factors predicting them present investigators with unique challenges. There is little systematic guidance for measuring these outcomes and exposures within the ICU setting. As a result measurement methods are often variable and noncomparable across studies.Methods We use examples from the critical care literature to describe measurement as it relates to three key elements of clinical studies: subjects, outcomes and exposures, and time. Using this framework we review the principles and challenges of measurement and make recommendations for long-term outcomes research in the field of critical care medicine.Discussion Relevant challenges discussed include: (a) selection bias and heterogeneity of ICU research subjects, (b) appropriate selection and measurement of outcome and exposure variables, and (c) accounting for the effect of time in the exposure-outcome relationship, including measurement of baseline data and time-varying variables.Conclusions Addressing these methodological challenges will advance research aimed at improving the long-term outcomes of ICU survivors.Electronic Supplementary Material Electronic supplementary material to this paper can be obtained by using the Springer Link server located at .This research was supported by National Institutes of Health (ALI SCCOR Grant # P050 HL 73994-01). D.M.N. is supported by Clinician-Scientist Awards from the Canadian Institutes of Health Research and the University of Toronto, and a Detweiler Fellowship from the Royal College of Physicians and Surgeons of Canada.     

Depression in general intensive care unit survivors: a systematic review

Purpose  To critically review data on the prevalence of depressive symptoms in general intensive care unit (ICU) survivors, risk factors for these symptoms, and their impact on health-related quality of life (HRQOL). Methods  We conducted a systematic review using Medline, EMBASE, Cochrane Library, CINAHL, PsycINFO, and a hand-search of 13 journals. Results  Fourteen studies were eligible. The median point prevalence of “clinically significant” depressive symptoms was 28% (total n = 1,213). Neither sex nor age were consistent risk factors for post-ICU depression, and severity of illness at ICU admission was consistently not a risk factor. Early post-ICU depressive symptoms were a strong risk factor for subsequent depressive symptoms. Post-ICU depressive symptoms were associated with substantially lower HRQOL. Conclusions  Depressive symptoms are common in general ICU survivors and negatively impact HRQOL. Future studies should address how factors related to individual patients, critical illness and post-ICU recovery are associated with depression in ICU survivors.     

Effect of interhospital transfer on resource utilization and outcomes at a tertiary pediatric intensive care unit

Purpose

The study aimed to examine the effect of interhospital transfer on resource utilization and clinical outcomes at a tertiary pediatric intensive care unit (PICU) among patients with sepsis or respiratory failure.

Materials and methods

Data on 2146 consecutive admissions with respiratory failure or sepsis to the PICU were analyzed. Data included demographics, admission source, and outcomes. Admission source was classified as interhospital transfer from the emergency departments (ED), wards, or PICUs of referring hospitals; or from the study hospital ED (direct).

Results

Compared with direct admissions, inter-PICU transfers had higher crude mortality (odds ratio, 1.93; 95% confidence interval, 1.31-2.84) but not significant mortality difference (odds ratio, 1.16; 95% confidence interval, 0.71-1.86) after adjusting for illness severity, age, and sex. Conversely, ED transfers had lower PICU mortality than direct ED admissions. Children with transfer admissions stayed significantly longer and used more intensive care technology in the study PICU than children directly admitted (P < .01). In comparisons within quartiles of mortality risk, inter-PICU transfers had longer hospitalization and higher mortality in all but the highest quartile.

Conclusions

Interhospital transfer, particularly inter-PICU transfer, was associated with significant hospital resource consumption that often correlated with admission illness severity. Future prospective studies should identify determinants of pretransfer illness severity and investigate decision making underlying interhospital transfer.     

Significance of new-onset prolonged sinus tachycardia in a medical intensive care unit: a prospective observational study

Objective

Few data are available on sinus tachycardia among medical intensive care unit (ICU) patients. We investigated new critical illnesses related to new-onset prolonged sinus tachycardia (NOPST) and the relationship of NOPST with ICU mortality.

Methods

The heart rate (HR) of all enrolled patients was monitored hourly over a 12-month period, and NOPST was defined as sinus tachycardia (>100 beats/min) with an increase in HR of more than 20% from the baseline value lasting longer than 6 hours.

Results

Among the 522 patients enrolled, the average mean HR was 96.1 ± 18.4 beats/min. Fifty-two (10.0%) patients met the criteria for NOPST; pneumonia, delirium, septic shock, acute respiratory distress syndrome, catheter-related infections, and mechanical ventilator–related problems were related to the occurrence of NOPST. The ICU mortality rate in patients with a NOPST duration of more than 72 hours was higher compared with other patients with NOPST (60.0% vs 18.5%; P = .002). A high daily mean HR rather than NOPST was a significant predictor of ICU mortality (odds ratio, 1.415; 95% confidence interval, 1.177-1.700).

Conclusions

Although NOPST was not associated with ICU mortality, it indicates the presence of new critical events in the medical ICU setting.     

Quality of life in adult survivors of critical illness: A systematic review of the literature

Objective: To determine how the quality of life (QOL) of intensive care unit (ICU) survivors compares with the general population, changes over time, and is predicted by baseline characteristics. Design: Systematic literature review including MEDLINE, EMBASE, CINAHL and Cochrane Library. Eligible studies measured QOL 30 days after ICU discharge using the Medical Outcomes Study 36-item Short Form (SF-36), EuroQol-5D, Sickness Impact Profile, or Nottingham Health Profile in representative populations of adult ICU survivors. Disease-specific studies were excluded. Measurements and results: Of 8,894 citations identified, 21 independent studies with 7,320 patients were reviewed. Three of three studies found that ICU survivors had significantly lower QOL prior to admission than did a matched general population. During post-discharge follow-up, ICU survivors had significantly lower QOL scores than the general population in each SF-36 domain (except bodily pain) in at least four of seven studies. Over 1–12 months of follow-up, at least two of four studies found clinically meaningful improvement in each SF-36 domain except mental health and general health perceptions. A majority of studies found that age and severity of illness predicted physical functioning. Conclusions: Compared with the general population, ICU survivors report lower QOL prior to ICU admission. After hospital discharge, QOL in ICU survivors improves but remains lower than general population levels. Age and severity of illness are predictors of physical functioning. This systematic review provides a general understanding of QOL following critical illness and can serve as a standard of comparison for QOL studies in specific ICU subpopulationsAn erratum to this article can be found at     

The risk assessment tool for intensive care unit readmission: A systematic review and meta-analysis

ObjectiveTo review and evaluate existing risk assessment tools for intensive care unitreadmission.MethodsNine electronic databases (Medline, CINAHL, Web of Science, Cochrane Library, Embase, Sino Med, CNKI, VIP, and Wan fang) were systematically searched from their inception to September 2022. Two authors independently extracted data from the literature included. Meta-analysis was performed under the bivariate modeling and summary receiver operating characteristic curve method.ResultsA total of 29 studies were included in this review, among which 11 were quantitatively Meta-analyzed. The results showed Stability and Workload Index for Transfer: Sensitivity = 0.55, Specificity = 0.65, Area under curve = 0.63. And Early warning score: Sensitivity = 0.78, Specificity = 0.83, Area under curve = 0.88. The remaining tools included scores, nomograms, machine learning models, and deep learning models. These studies, with varying reports on thresholds, case selection, data preprocessing, and model performance, have a high risk of bias.ConclusionWe cannot identify a tool that can be used directly in intensive care unit readmission risk assessment. Scores based on early warning score are moderately accurate in predicting readmission, but there is heterogeneity and publication bias that requires model adjustment for local factors such as resources, demographics, and case mix. Machine learning models present a promising modeling technique but have a high methodological bias and require further validation.Implications for clinical practiceUsing reliable risk assessment tools is essential for the early identification of unplanned intensive care unit readmission risk in critically ill patients.  A reliable risk assessment tool must be developed, which is the focus of further research.     

Research issues in the evaluation of cognitive impairment in intensive care unit survivors

Neuropsychological assessment has been utilized extensively in the research of cognitive outcomes associated with medical illnesses, such as HIV, and post-surgical procedures, such as coronary artery bypass graft. However, few investigations of intensive care unit (ICU) survivors have examined cognitive function as a clinical outcome. Significant clinical questions exist regarding the impact of critical illness on long-term cognitive function. Many of these questions can be systematically evaluated through the use of standardized neuropsychological assessment instruments within the context of well designed, prospective research trials. This review will provide information for clinical researchers interested in the study of neuropsychological outcomes in intensive care unit survivors ( a comparison article in this issue will address clinical issues related to cognitive functioning).Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Long-term persistence of quality improvements for an intensive care unit communication initiative using the VALUE strategy

Purpose

Communication in the intensive care unit (ICU) is an important component of quality ICU care. In this report, we evaluate the long-term effects of a quality improvement (QI) initiative, based on the VALUE communication strategy, designed to improve communication with family members of critically ill patients.

Materials and Methods

We implemented a multifaceted intervention to improve communication in the ICU and measured processes of care. Quality improvement components included posted VALUE placards, templated progress note inclusive of communication documentation, and a daily rounding checklist prompt. We evaluated care for all patients cared for by the intensivists during three separate 3 week periods, pre, post, and 3 years following the initial intervention.

Results

Care delivery was assessed in 38 patients and their families in the pre-intervention sample, 27 in the post-intervention period, and 41 in follow-up. Process measures of communication showed improvement across the evaluation periods, for example, daily updates increased from pre 62% to post 76% to current 84% of opportunities.

Conclusions

Our evaluation of this quality improvement project suggests persistence and continued improvements in the delivery of measured aspects of ICU family communication. Maintenance with point-of-care-tools may account for some of the persistence and continued improvements.     

Prognostic models based on administrative data alone inadequately predict the survival outcomes for critically ill patients at 180 days post-hospital discharge

There is interest in evaluating the quality of critical care by auditing patient outcomes after hospital discharge. Risk adjustment using acuity of illness scores, such as Acute Physiology and Chronic Health Evaluation (APACHE III) scores, derived from clinical databases is commonly performed for in-hospital mortality outcome measures. However, these clinical databases do not routinely track patient outcomes after hospital discharge. Linkage of clinical databases to administrative data sets that maintain records on patient survival after discharge can allow for the measurement of survival outcomes of critical care patients after hospital discharge while using validated risk adjustment methods.     

Long-term cognitive impairment and delirium in intensive care: A prospective cohort study

Background

Whilst there is a growing body of research exploring the effect of delirium in intensive care unit (ICU) patients, the relationship between patient delirium and long-term cognitive impairment has not been investigated in settings where low rates of delirium have been reported.

Characterizing critical care physician staffing in rural America: A description of Iowa intensive care unit staffing

Purpose

This study aimed to characterize intensive care unit (ICU) physician staffing patterns in a predominantly rural state.

Materials and Methods

A prospective telephone survey of ICU nurse managers in all Iowa hospitals with an ICU was conducted.

Results

Of 122 Iowa hospitals, 64 ICUs in 58 (48%) hospitals were identified, and 46 (72%) responded to the survey. Most ICUs (96%) used an open admission model and cared for undifferentiated medical and surgical patients (88%), and only 27% of open ICUs required critical care or pulmonary consultation for admitted patients. Most (59%) Iowa ICUs had a critical care physician or pulmonologist available, and high-intensity staffing was practiced in 30% of ICUs. Most physicians identified as practicing critical care (63%) were not board certified in critical care. Critical care physicians were available in a minority of hospitals routinely for inpatient intubation and cardiac arrest management (29% and 10%, respectively), and emergency physicians and other practitioners commonly responded to emergencies throughout the hospital.

Conclusions

Many Iowa hospitals have ICUs, and staffing patterns in Iowa ICUs mirror closely national staffing practices. Most ICUs are multispecialty, open ICUs in community hospitals. These factors should inform training and resource allocation for intensivists in rural states.     

Paediatric index of mortality (PIM): a mortality prediction model for children in intensive care

Objective: To develop a logistic regression model that predicts the risk of death for children less than 16 years of age in intensive care, using information collected at the time of admission to the unit. Design: Three prospective cohort studies, from 1988 to 1995, were used to determine the variables for the final model. A fourth cohort study, from 1994 to 1996, collected information from consecutive admissions to all seven dedicated paediatric intensive care units in Australia and one in Britain. Results: 2904 patients were included in the first three parts of the study, which identified ten variables for further evaluation. 5695 children were in the fourth part of the study (including 1412 from the third part); a model that used eight variables was developed on data from four of the units and tested on data from the other four units. The model fitted the test data well (deciles of risk goodness-of-fit test p=0.40) and discriminated well between death and survival (area under the receiver operating characteristic plot 0.90). The final PIM model used the data from all 5695 children and also fitted well (p=0.37) and discriminated well (area 0.90). Conclusions: Scores that use the worst value of their predictor variables in the first 12–24 h should not be used to compare different units: patients mismanaged in a bad unit will have higher scores than similar patients managed in a good unit, and the bad unit‘s high mortality rate will be incorrectly attributed to its having sicker patients. PIM is a simple model that is based on only eight explanatory variables collected at the time of admission to intensive care. It is accurate enough to be used to describe the risk of mortality in groups of children. Received: 17 June 1996 Accepted: 28 September 1996     

Deep venous thrombosis: clinically silent in the intensive care unit

PURPOSE: The reliability of clinical signs and the physical examination in the evaluation of deep venous thrombosis (DVT) in the critically ill is unknown. The purpose of this study was to determine the diagnostic properties of clinical examination for signs of DVT in a cohort of medical-surgical intensive care unit (ICU) patients using screening compression ultrasonography as a reference standard. MATERIALS AND METHODS: We prospectively included patients older than 18 years with an expected length of ICU stay of more than 72 hours. Patients underwent bilateral lower limb screening compression ultrasound twice weekly and structured physical examination twice weekly by 2 independent trained research coordinators blinded to the ultrasonography results. We classified patients according to 2 methods: method 1, a DVT Risk Stratification System of 3 categories and method 2, a DVT Risk Score, both of which use the history and physical examination to stratify patients for their risk of DVT. RESULTS: We included 239 patients in our study, 32 of whom had DVT based on the results of their compression ultrasound. We excluded 7 patients with DVT on ICU admission and 2 who did not undergo any structured examinations. We matched controls with cases (9:1) based on duration of ICU stay. Cases and controls were then allocated to low, moderate, and high risk strata for DVT. Using method 1, the area under the receiver operating characteristic curve (AUC) was 0.57 (95% CI, 0.33-0.78, P = .01). Using method 2, the AUC was 0.59 (95% CI, 0.42-0.75, P = .02). An AUC of 1.0 indicates an ideal test, and AUC of 0.50 indicates a test with no diagnostic utility. CONCLUSIONS: The history and physical examination for DVT are not useful in detecting lower limb DVT in the ICU.     

Facilitators and barriers to initiating change in medical intensive care unit survivors with alcohol use disorders: A qualitative study

Purpose

Alcohol abuse and dependence are collectively referred to as alcohol use disorders (AUD). An AUD is present in up to one third of patients admitted to an intensive care unit (ICU). We sought to understand the barriers and facilitators to change in ICU survivors with an AUD to provide a foundation upon which to tailor alcohol-related interventions.

Methods

We used a qualitative approach with a broad constructivist framework, conducting semistructured interviews in medical ICU survivors with an AUD. Patients were included if they were admitted to 1 of 2 medical ICUs and were excluded if they refused participation, were unable to participate, or did not speak English. Digitally recorded and professionally transcribed interviews were analyzed using a general inductive approach and grouped into themes.

Results

Nineteen patients were included, with an average age of 51 (interquartile range, 36-51) years and an average Acute Physiology and Chronic Health Evaluation II score of 9 (interquartile range, 5-13); 68% were white, 74% were male, and the most common reason for admission was alcohol withdrawal (n = 8). We identified 5 facilitators of change: empathy of the inpatient health care environment, recognition of accumulating problems, religion, pressure from others to stop drinking, and trigger events. We identified 3 barriers to change: missed opportunities, psychiatric comorbidity, and cognitive dysfunction. Social networks were identified as either a barrier or facilitator to change depending on the specific context.

Conclusions

Alcohol-related interventions to motivate and sustain behavior change could be tailored to ICU survivors by accounting for unique barriers and facilitators.     

Sleep monitoring in the intensive care unit: comparison of nurse assessment, actigraphy and polysomnography

Objective  Sleep loss and sleep disruption are common in critically ill patients and may adversely affect clinical outcomes. Although polysomnography remains the most accurate and reliable way to measure sleep, it is costly and impractical for regular use in the intensive care unit. This study evaluates the accuracy of two other methods currently used for measuring sleep, actigraphy (monitoring of gross motor activity) and behavioural assessment by the bedside nurse, by comparing them to overnight polysomnography in critically ill patients. Design  Observational study with simultaneous polysomnography, actigraphy and behavioural assessment of sleep. Setting  Medical-surgical intensive care unit. Patients and participants  Twelve stable, critically ill, mechanically ventilated patients [68 (13) years, Glasgow coma scale 11 (0)]. Interventions  None. Measurements and results  Sleep was severely disrupted, reflected by decreased total sleep time and sleep efficiency, high frequency of arousals and awakenings and abnormal sleep architecture. Actigraphy overestimated total sleep time and sleep efficiency. The overall agreement between actigraphy and polysomnography was <65%. Nurse assessment underestimated the number of awakenings from sleep. Estimated total sleep time, sleep efficiency and number of awakenings by nurse assessment did not correlate with polysomnographic findings. Conclusions  Actigraphy and behavioural assessment by the bedside nurse are inaccurate and unreliable methods to monitor sleep in critically ill patients.     

Intensive care unit exposures for long-term outcomes research: development and description of exposures for 150 patients with acute lung injury

PURPOSE: Long-term follow-up studies in critical care have described survivors' outcomes, but provided less insight into the patient/disease characteristics and intensive care therapies ("exposures") associated with these outcomes. Such insights are essential for improving patients' long-term outcomes. This report describes the development of a strategy for comprehensively measuring relevant exposures for long-term outcomes research, and presents empiric results from its implementation. MATERIALS AND METHODS: A multistep, iterative process was used to develop the exposures strategy. First, a comprehensive list of potential exposures was generated and subsequently reduced based on feasibility, redundancy, and relevance criteria. Next, data abstraction methods were designed and tested. Finally, the strategy was implemented in 150 patients with acute lung injury with iterative refinement. RESULTS: The strategy resulted in the development of more than 60 unique exposures requiring less than 45 minutes per patient-day for data collection. Most exposures had minimal missing data and adequate reliability. These data revealed that evidence-based practices including lower tidal volume ventilation, spontaneous breathing trials, sedation interruption, adequate nutrition, and blood glucose of less than 6.1 mmol/L (110 mg/dL) occurred in only 23% to 50% of assessments. CONCLUSIONS: Using a multistep, iterative process, a comprehensive and feasible exposure measurement strategy for long-term outcomes research was successfully developed and implemented.