Does Pediatric Index of Mortality “Score” in Colombia?
Corresponding Author: Sarfaraz Rahiman, Department of Paediatric Intensive Care, Queensland Children’s Hospital, Brisbane, Queensland, Australia, Phone: +61 730681004, e-mail: email@example.com
How to cite this article Rahiman S. Does Pediatric Index of Mortality “Score” in Colombia? Indian J Crit Care Med 2020;24(11):1018–1019.
Source of support: Nil
Conflict of interest: None
Pediatric index of mortality (PIM)-2 and PIM3 are the most recent versions of severity of illness scoring generated from a pediatric intensive care unit (PICU) population in Australia and the United Kingdom. The authors present a single-center evaluation of a performance of these scores in a PICU in Colombia. PIM3 seemed to demonstrate a marginally better performance at predicting mortality, although the discrimination was similar for both scores. Incorporation of this approach to the rest of the units throughout the country would help with benchmarking PICU performance.
Keywords: Pediatric index of mortality, Pediatric intensive care unit, Severity of illness scoring..
Benchmarking pediatric intensive care unit (PICU) performance can be challenging across different units, especially if varying levels of illness severity exist in the patients admitted. The perceived value of an objective assessment of individual units led to the development of severity of illness scores over the last three decades. Such scores use variable parameters to predict an expected mortality risk, which is then used to generate the risk-adjusted standardized mortality rate. Logistic regression models on large datasets of PICU admissions were used to generate the scores. The pediatric risk of mortality (PRISM) and the pediatric index of mortality (PIM) are among the most popular scores used.1 The PIM was initially developed using data from 5,695 PICU admissions in Australia and the United Kingdom.2 It has further been revised since then with PIM2 and PIM3 versions published subsequently.3,4
With every new version of a particular score, the authors have aimed to better define the mortality risk by reevaluating the parameters in increasingly larger PICU patient populations.2–4 Internal validation ensures that these scores perform well in the settings they have been created in.5,6 The updated versions are intended to account for an ever-changing critically ill patient population and potential advances in diagnosis and therapy. There have been attempts to validate the performance of various versions of the PIM score externally in areas other than their countries of origin. Such attempts have yielded mixed results with some studies showing agreement7–13 while others have not.14–16 The PIM has even been tested in a non-PICU17 environment and in patients retrieved to intensive care.18
Like many prior attempts, Lopez et al. have conducted a single-center evaluation of the performance of the most recent versions of PIM scores in a PICU in Bogota, Colombia (IJCCM_19_681_R3. Comparison on performance of the pediatric index of mortality (PIM)-2 and PIM-3 scores in the pediatric care unit of a high complexity institution. Indian J Crit Care Med 2020;24(10)). The study has used similar statistical methodology as employed in the original and subsequent validation studies. However, the use of the net reclassification index in the interpretation of such data needs caution.19 The data have been cross-checked for accuracy, and two independent statistical reviews have been performed as confirmed by the authors. In 722 patients with a crude mortality rate of 3.74%, good discrimination (the ability to differentiate between survivors and nonsurvivors) was demonstrated by both scores. However, PIM3 appeared to be a better predictor of the mortality rate in comparison to PIM2, which overestimated the risk of mortality.
The manuscript recognizes the limitation of using these scores in small number of patients. Mortality prediction scores have little value when applied to a single patient or a small patient subset. Inherent differences in the patient population in different geographic regions may play a role, even though the physiological variables may not be different. PIM3 performance was adequate in these settings—is this only by chance? Would another subset reveal possibly different results? Unfortunately, we will only have these answers with broader application of these scores, and one needs to be circumspect with drawing major conclusions.
That being said, the authors have to be commended for performing a first of its kind study in Colombia. The value of this manuscript may not lie in the observed results but the potential future implications for the critical care community in Colombia. This should serve as a launching pad for further incorporation of severity of illness scoring across the PICUs in the rest of the country to serve its intended goal for benchmarking. As to the performance of the score, the perfect score applicable to every PICU setting anywhere in the world may remain largely elusive.
2. Shann F, Pearson G, Slater A, Wilkinson K. Paediatric index of mortality (PIM): a mortality prediction model for children in intensive care. Intensive Care Med 1997;23(2):201–207. DOI: 10.1007/s001340050317.
4. Straney L, Clements A, Parslow RC, Pearson G, Shann F, Alexander J, et al. Paediatric index of mortality 3: an updated model for predicting mortality in pediatric intensive care*. Pediatr Crit Care Med 2013;14(7):673–681. DOI: 10.1097/PCC.0b013e31829760cf.
5. Slater A, Shann F. The suitability of the pediatric index of mortality (PIM), PIM2, the pediatric risk of mortality (PRISM), and PRISM III for monitoring the quality of pediatric intensive care in Australia and New Zealand. Pediatr Crit Care Med 2004;5(5):447–454. DOI: 10.1097/01.PCC.0000138557.31831.65.
7. Niederwanger C, Varga T, Hell T, Stuerzel D, Prem J, Gassner M, et al. Comparison of pediatric scoring systems for mortality in septic patients and the impact of missing information on their predictive power: a retrospective analysis. PeerJ 2020;8:e9993. DOI: 10.7717/peerj.9993.
8. Mestrovic J, Kardum G, Polic B, Omazic A, Stricevic L, Sistic A. Applicability of the Australian and New Zealand Paediatric intensive care registry diagnostic codes and paediatric index of mortality 2 scoring system in a Croatian paediatric intensive care unit. Eur J Pediatr 2005;164(12):783–784. DOI: 10.1007/s00431-005-1755-3.
9. Rady HI, Mohamed SA, Mohssen NA, ElBaz M. Application of different scoring systems and their value in pediatric intensive care unit. Egypt Pediat Associat Gazette 2014;62(3):59–64. DOI: 10.1016/j.epag.2014.10.003.
10. Patki VK, Raina S, Antin JV. Comparison of severity scoring systems in a pediatric intensive care unit in India: a single-center prospective, observational cohort study. J Pediat Intens Care 2017;6(2):98–102. DOI: 10.1055/s-0036-1584811.
11. Imamura T, Nakagawa S, Goldman R, Fujiwara T. Validation of pediatric index of mortality 2 (PIM2) in a single pediatric intensive care unit in Japan. Intensive Care Med 2011;38(4):649–654. DOI: 10.1007/s00134-011-2460-5.
12. Wong JJ, Hornik CP, Mok YH, Loh TF, Lee JH. Performance of the paediatric index of mortality 3 and paediatric logistic organ dysfunction 2 scores in critically ill children. Ann Acad Med Singap 2018;47(8):285–290.
13. Wolfler A, Osello R, Gualino J, Calderini E, Vigna G, Santuz P, et al. The Importance of mortality risk assessment: validation of the pediatric index of mortality 3 score. Pediatr Crit Care Med 2016;17(3):251–256. DOI: 10.1097/PCC.0000000000000657.
14. Arias Lopez MP, Fernández AL, Ratto ME, Saligari L, Serrate AS, Ko IJ, et al. Pediatric index of mortality 2 as a predictor of death risk in children admitted to pediatric intensive care units in Latin America: a prospective, multicenter study. J Crit Care 2015;30(6):1324–1330. DOI: 10.1016/j.jcrc.2015.08.001.
15. Arias López MP, Boada N, Fernández A, Fernández AL, Ratto ME, Serrate AS. Performance of the pediatric index of mortality 3 score in PICUs in Argentina: a prospective, national multicenter study. Pediatr Crit Care Med 2018;19(12):e653–e661. DOI: 10.1097/PCC.0000000000001741.
16. Sankar J, Gulla KM, Kumar UV, Lodha R, Kabra SK. Comparison of outcomes using pediatric index of mortality (PIM)-3 and PIM-2 models in a pediatric intensive care unit. Indian Pediatr 2018;55(11):972–974. DOI: 10.1007/s13312-018-1421-2.
18. Rahiman S, Sadasivam K, Ridout DA, Tasker RC, Ramnarayan P. Comparison of three different timeframes for pediatric index of mortality data collection in transported intensive care admissions*. Pediatr Crit Care Med 2014;15(3):e120–e127. DOI: 10.1097/PCC.0000000000000058.
19. Pepe MS, Fan J, Feng Z, Gerds T, Hilden J. The net reclassification index (NRI): a misleading measure of prediction improvement even with independent test data sets. Stat Biosci 2015;7(2):282–295. DOI: 10.1007/s12561-014-9118-0.
© The Author(s). 2020 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.