Are We Exchanging Morbidity for Mortality in Pediatric Intensive Care?* Troy E. Dominguez, MD Cardiac Intensive Care Division of Critical Care Medicine Great Ormond Street Hospital for Children NHS Foundation Trust London, United Kingdom
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ith the improvement in ICU mortality rates in the 1990s, assessment of functional outcomes in PICU survivors was recognized to be important. However, the tools available to do so at that time were limited in adults and nonexistent in children. The Glasgow Outcome Scale, having been published in 1975 (1), was and still is used as a way to grossly categorize functional disability in adults, but is inappropriate for use in children. In 1991, Fiser (2) developed and validated the pediatric performance category scales (pediatric overall performance category [POPC] and pediatric cerebral performance category [PCPC] scores). These scales, similar to the Glasgow Outcome Scale, categorize disability in children into six categories ranging from no disability (normal) to death and are now commonly in use. Other instruments for pediatric outcome assessment have been developed but may be resource intensive to administer and/or limited to certain patient populations. Recognizing the limitations of our present tools for assessing PICU outcomes, researchers at the Collaborative Pediatric Critical Care Research Network (CPCCRN) have developed the Functional Status Scale (FSS) for pediatric hospitalized patients as a tool that is easy to use, objective, quantitative, and appropriate for large-scale outcomes research (3). The FSS has been validated and is currently being used in more than 10,000 patients as part of research being done by the CPCCRN (4). In a recent follow-up publication since the FSS validation study (4), the authors identified two important findings when comparing the FSS to the pediatric performance category scales. First, FSS scores correlated well with PCPC/POPC scores both at admission and discharge. Second, they identified that the dispersion (spread) of the FSS scores increased with worsening disability category of the PCPC/POPC scores. The last finding suggests a lack of precision by the pediatric performance category scales since wider dispersion of FSS scores in a category results in more overlap across categories. Dependency on some subjective assessment
*See also p. 821. Key Words: functional outcomes; pediatric intensive care; severity of illness The author has disclosed that he does not have any potential conflicts of interest. Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000281
898
www.pccmjournal.org
for PCPC/POPC disability categories is thought to account for this dispersion. In this issue of Pediatric Critical Care Medicine (5), investigators from the Collaborative Pediatric Critical Care Research Network (CPCCRN) identify the prevalence of new morbidity in surviving PICU patients selected from seven institutions participating in the CPCCRN over a 10-month time period. Based on knowledge of the dispersion for each POPC/PCPC category from the authors’ recent study (4), they categorized patients as having five functional states: good, mildly abnormal, moderately abnormal, severely abnormal, and very severely abnormal. The authors also defined new morbidity as change in FSS by greater than or equal to 3 from baseline to hospital discharge. The study is remarkable in that more than 5,000 patients were enrolled. The average morbidity rate at PICU discharge was 4.8%. There were significant differences in morbidity and mortality rates across the sites, and the correlation between morbidity and mortality rates was weak, which suggests potential utility with this methodology as a useful outcome measure. Since there was the potential for patients with significant new morbidity not to be identified because of an improvement in another domain of the FSS, the authors investigated this possibility and found this was not the case. Analysis by diagnostic groups demonstrated that new morbidity was highest in those patients admitted with neurologic disease, cardiovascular disease, and malignancy; varied significantly by diagnosis; and was identified in all diagnostic groups except for endocrinologic diagnoses. Operative categories with the highest morbidity rates included general surgery and cardiac surgery. New morbidity varied by age category with neonates (< 2 wk old) having the highest morbidity rates (~9–11%). These rates were also higher than any operative or diagnostic group, suggesting a sensitivity of the FSS to age or more likely that this is a vulnerable age group. The rate of new morbidity did not vary significantly by baseline functional status, but those children with a baseline level of very severe dysfunction had the lowest new morbidity rates (< 2%) due to very severe baseline dysfunction. So have pediatric critical care specialists exchanged higher morbidity rates for an improvement in mortality rates? As the authors state in their discussion, historical data from a large multi-institutional study from the 1990s demonstrated a new morbidity rate (defined as a change ≥ 2 across pediatric performance scale categories from admission to discharge) of 3.1% and a mortality rate of 4.6% (6). This gave a combined morbidity and mortality rate of 7.7%. In the present study, the authors have identified a new morbidity rate of 4.8% and a hospital mortality rate of 2.4% for a combined morbidity and mortality rate of 7.2%. Therefore, these rates might suggest little improvement in combined morbidity and mortality over time, with the rate of morbidity now being higher than mortality. Can this finding be explained by a change is case-mix or November 2014 • Volume 15 • Number 9
Editorials
baseline functional status? We know the number of children treated with chronic conditions and comorbidity has increased over time, challenging our abilities in the PICU (7, 8). The FSS does not appear to be measuring different new morbidity rates by baseline functional status, but differences arising due to case-mix are unknown. As the authors recognized, the methodology of identifying new morbidity using the FSS is different and may account for the higher rate observed in the present study by identifying changes in functional status better. Conversely, an increase in baseline FSS greater than or equal to 3 was empirically chosen to represent new morbidity. An additional 6% of the patients had an increase in FSS by 2 at hospital discharge, mainly represented by an increase in scores in the motor and feeding domains of the FSS, which raises the possibility that new morbidity is underestimated (5). The CPCCRN have now impressively achieved two important steps in preparation for the Trichotomous Outcome Prediction in Critical Care study that will attempt to predict the outcome of PICU using the three outcomes of good survival, poor survival, and death. These two steps were validation of the FSS as a measure of functional status and refining the optimal time measurement for severity of illness assessment (9). Although higher morbidity rates are worrisome, one can hope that the FSS has improved identifying important PICU morbidity, rather than our morbidity rate having increased over time, and that this knowledge will lead to processes and interventions for further improvement.
REFERENCES
1. Jennet B, Bond M: Assessment of outcome after brain damage. Lancet 1975; 1:480–484 2. Fiser DH: Assessing the outcome of pediatric intensive care. J Pediatr 1992; 121:68–74 3. Pollack MM, Holubkov R, Glass P, et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network: Functional Status Scale: New pediatric outcome measure. Pediatrics 2009; 124:e18–e28 4. Pollack MM, Holubkov R, Funai T, et al: Relationship between the functional status scale and the pediatric overall performance category and pediatric cerebral performance category scales. JAMA Pediatr 2014; 168:671–676 5. Pollack MM, Holubkov R, Funai T, et al; for the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network: Pediatric Intensive Care Outcomes: Development of New Morbidities During Pediatric Critical Care. Pediatr Crit Care Med 2014; 15:821–827 6. Fiser DH, Tilford JM, Roberson PK: Relationship of illness severity and length of stay to functional outcomes in the pediatric intensive care unit: A multi-institutional study. Crit Care Med 2000; 28:1173–1179 7. Edwards JD, Houtrow AJ, Vasilevskis EE, et al: Chronic conditions among children admitted to U.S. pediatric intensive care units: Their prevalence and impact on risk for mortality and prolonged length of stay. Crit Care Med 2012; 40:2196–2203 8. Zabrocki LA, Brogan TV, Statler KD, et al: Extracorporeal membrane oxygenation for pediatric respiratory failure: Survival and predictors of mortality. Crit Care Med 2011; 39:364–370 9. Pollack MM, Dean JM, Butler J, et al: The ideal timing for critical care severity of illness assessment. Pediatr Crit Care Med 2013; 14:448–453
Sepsis in Children: A Dark Cloud With a Silver Lining* The disease, at its early stage, is easy to cure but hard to diagnose. At a later stage, it is easy to diagnose but impossible to cure. —Niccolò Machiavelli (1) Niranjan Kissoon, MBBS, FAAP, FCCM, FACPE BC Children’s Hospital and Sunny Hill Health Centre for Children BC & BC Children’s Hospital Critical Care – Global Child Health Department of Pediatrics and Emergency Medicine University of British Columbia Child and Family Research Institute Vancouver, BC, Canada *See also p. 828. Key Words: intensive care; International Classification of Diseases; pediatric; sepsis; septic shock The author has disclosed that he does not have any potential conflicts of interest. Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000264
Pediatric Critical Care Medicine
T
he prevalence of sepsis in children in the United States is rising while mortality rates are falling (2, 3). However, the lack of a gold standard to define sepsis handicaps efforts to address what is a major, mostly silent killer in the United States (2, 3) and the greatest burden in terms of disability-adjusted lives lost worldwide (4). The study by Ruth et al (5) in this issue of Pediatric Critical Care Medicine underlines the difficulty in defining sepsis. This is a retrospective review of prospectively collected data from the PICUs of 43 U.S. children’s hospitals from 2004 to 2012 in the Pediatric Healthcare Information System (PHIS) Database. The authors reported a pediatric severe sepsis (PSS) prevalence of 7.7% with associated mortality rate of 14.4%. Age (< 1 yr), underlying cardiovascular disease and multiple organ dysfunction, was associated with higher odds of mortality. Severe sepsis prevalence rate increased from 2004 to 2012 (6.2–7.7%; p < 0.001), whereas the mortality rate decreased from 18.9% to 12.0% (p
W
ith the improvement in ICU mortality rates in the 1990s, assessment of functional outcomes in PICU survivors was recognized to be important. However, the tools available to do so at that time were limited in adults and nonexistent in children. The Glasgow Outcome Scale, having been published in 1975 (1), was and still is used as a way to grossly categorize functional disability in adults, but is inappropriate for use in children. In 1991, Fiser (2) developed and validated the pediatric performance category scales (pediatric overall performance category [POPC] and pediatric cerebral performance category [PCPC] scores). These scales, similar to the Glasgow Outcome Scale, categorize disability in children into six categories ranging from no disability (normal) to death and are now commonly in use. Other instruments for pediatric outcome assessment have been developed but may be resource intensive to administer and/or limited to certain patient populations. Recognizing the limitations of our present tools for assessing PICU outcomes, researchers at the Collaborative Pediatric Critical Care Research Network (CPCCRN) have developed the Functional Status Scale (FSS) for pediatric hospitalized patients as a tool that is easy to use, objective, quantitative, and appropriate for large-scale outcomes research (3). The FSS has been validated and is currently being used in more than 10,000 patients as part of research being done by the CPCCRN (4). In a recent follow-up publication since the FSS validation study (4), the authors identified two important findings when comparing the FSS to the pediatric performance category scales. First, FSS scores correlated well with PCPC/POPC scores both at admission and discharge. Second, they identified that the dispersion (spread) of the FSS scores increased with worsening disability category of the PCPC/POPC scores. The last finding suggests a lack of precision by the pediatric performance category scales since wider dispersion of FSS scores in a category results in more overlap across categories. Dependency on some subjective assessment
*See also p. 821. Key Words: functional outcomes; pediatric intensive care; severity of illness The author has disclosed that he does not have any potential conflicts of interest. Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000281
898
www.pccmjournal.org
for PCPC/POPC disability categories is thought to account for this dispersion. In this issue of Pediatric Critical Care Medicine (5), investigators from the Collaborative Pediatric Critical Care Research Network (CPCCRN) identify the prevalence of new morbidity in surviving PICU patients selected from seven institutions participating in the CPCCRN over a 10-month time period. Based on knowledge of the dispersion for each POPC/PCPC category from the authors’ recent study (4), they categorized patients as having five functional states: good, mildly abnormal, moderately abnormal, severely abnormal, and very severely abnormal. The authors also defined new morbidity as change in FSS by greater than or equal to 3 from baseline to hospital discharge. The study is remarkable in that more than 5,000 patients were enrolled. The average morbidity rate at PICU discharge was 4.8%. There were significant differences in morbidity and mortality rates across the sites, and the correlation between morbidity and mortality rates was weak, which suggests potential utility with this methodology as a useful outcome measure. Since there was the potential for patients with significant new morbidity not to be identified because of an improvement in another domain of the FSS, the authors investigated this possibility and found this was not the case. Analysis by diagnostic groups demonstrated that new morbidity was highest in those patients admitted with neurologic disease, cardiovascular disease, and malignancy; varied significantly by diagnosis; and was identified in all diagnostic groups except for endocrinologic diagnoses. Operative categories with the highest morbidity rates included general surgery and cardiac surgery. New morbidity varied by age category with neonates (< 2 wk old) having the highest morbidity rates (~9–11%). These rates were also higher than any operative or diagnostic group, suggesting a sensitivity of the FSS to age or more likely that this is a vulnerable age group. The rate of new morbidity did not vary significantly by baseline functional status, but those children with a baseline level of very severe dysfunction had the lowest new morbidity rates (< 2%) due to very severe baseline dysfunction. So have pediatric critical care specialists exchanged higher morbidity rates for an improvement in mortality rates? As the authors state in their discussion, historical data from a large multi-institutional study from the 1990s demonstrated a new morbidity rate (defined as a change ≥ 2 across pediatric performance scale categories from admission to discharge) of 3.1% and a mortality rate of 4.6% (6). This gave a combined morbidity and mortality rate of 7.7%. In the present study, the authors have identified a new morbidity rate of 4.8% and a hospital mortality rate of 2.4% for a combined morbidity and mortality rate of 7.2%. Therefore, these rates might suggest little improvement in combined morbidity and mortality over time, with the rate of morbidity now being higher than mortality. Can this finding be explained by a change is case-mix or November 2014 • Volume 15 • Number 9
Editorials
baseline functional status? We know the number of children treated with chronic conditions and comorbidity has increased over time, challenging our abilities in the PICU (7, 8). The FSS does not appear to be measuring different new morbidity rates by baseline functional status, but differences arising due to case-mix are unknown. As the authors recognized, the methodology of identifying new morbidity using the FSS is different and may account for the higher rate observed in the present study by identifying changes in functional status better. Conversely, an increase in baseline FSS greater than or equal to 3 was empirically chosen to represent new morbidity. An additional 6% of the patients had an increase in FSS by 2 at hospital discharge, mainly represented by an increase in scores in the motor and feeding domains of the FSS, which raises the possibility that new morbidity is underestimated (5). The CPCCRN have now impressively achieved two important steps in preparation for the Trichotomous Outcome Prediction in Critical Care study that will attempt to predict the outcome of PICU using the three outcomes of good survival, poor survival, and death. These two steps were validation of the FSS as a measure of functional status and refining the optimal time measurement for severity of illness assessment (9). Although higher morbidity rates are worrisome, one can hope that the FSS has improved identifying important PICU morbidity, rather than our morbidity rate having increased over time, and that this knowledge will lead to processes and interventions for further improvement.
REFERENCES
1. Jennet B, Bond M: Assessment of outcome after brain damage. Lancet 1975; 1:480–484 2. Fiser DH: Assessing the outcome of pediatric intensive care. J Pediatr 1992; 121:68–74 3. Pollack MM, Holubkov R, Glass P, et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network: Functional Status Scale: New pediatric outcome measure. Pediatrics 2009; 124:e18–e28 4. Pollack MM, Holubkov R, Funai T, et al: Relationship between the functional status scale and the pediatric overall performance category and pediatric cerebral performance category scales. JAMA Pediatr 2014; 168:671–676 5. Pollack MM, Holubkov R, Funai T, et al; for the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network: Pediatric Intensive Care Outcomes: Development of New Morbidities During Pediatric Critical Care. Pediatr Crit Care Med 2014; 15:821–827 6. Fiser DH, Tilford JM, Roberson PK: Relationship of illness severity and length of stay to functional outcomes in the pediatric intensive care unit: A multi-institutional study. Crit Care Med 2000; 28:1173–1179 7. Edwards JD, Houtrow AJ, Vasilevskis EE, et al: Chronic conditions among children admitted to U.S. pediatric intensive care units: Their prevalence and impact on risk for mortality and prolonged length of stay. Crit Care Med 2012; 40:2196–2203 8. Zabrocki LA, Brogan TV, Statler KD, et al: Extracorporeal membrane oxygenation for pediatric respiratory failure: Survival and predictors of mortality. Crit Care Med 2011; 39:364–370 9. Pollack MM, Dean JM, Butler J, et al: The ideal timing for critical care severity of illness assessment. Pediatr Crit Care Med 2013; 14:448–453
Sepsis in Children: A Dark Cloud With a Silver Lining* The disease, at its early stage, is easy to cure but hard to diagnose. At a later stage, it is easy to diagnose but impossible to cure. —Niccolò Machiavelli (1) Niranjan Kissoon, MBBS, FAAP, FCCM, FACPE BC Children’s Hospital and Sunny Hill Health Centre for Children BC & BC Children’s Hospital Critical Care – Global Child Health Department of Pediatrics and Emergency Medicine University of British Columbia Child and Family Research Institute Vancouver, BC, Canada *See also p. 828. Key Words: intensive care; International Classification of Diseases; pediatric; sepsis; septic shock The author has disclosed that he does not have any potential conflicts of interest. Copyright © 2014 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000264
Pediatric Critical Care Medicine
T
he prevalence of sepsis in children in the United States is rising while mortality rates are falling (2, 3). However, the lack of a gold standard to define sepsis handicaps efforts to address what is a major, mostly silent killer in the United States (2, 3) and the greatest burden in terms of disability-adjusted lives lost worldwide (4). The study by Ruth et al (5) in this issue of Pediatric Critical Care Medicine underlines the difficulty in defining sepsis. This is a retrospective review of prospectively collected data from the PICUs of 43 U.S. children’s hospitals from 2004 to 2012 in the Pediatric Healthcare Information System (PHIS) Database. The authors reported a pediatric severe sepsis (PSS) prevalence of 7.7% with associated mortality rate of 14.4%. Age (< 1 yr), underlying cardiovascular disease and multiple organ dysfunction, was associated with higher odds of mortality. Severe sepsis prevalence rate increased from 2004 to 2012 (6.2–7.7%; p < 0.001), whereas the mortality rate decreased from 18.9% to 12.0% (p
