Validation of a Paediatric Early Warning Score: first results and ...

Eur J Pediatr DOI 10.1007/s00431-014-2357-8

ORIGINAL ARTICLE

Validation of a Paediatric Early Warning Score: first results and implications of usage Joris Fuijkschot & Bastiaan Vernhout & Joris Lemson & Jos M. T. Draaisma & Jan L. C. M. Loeffen

Received: 16 April 2014 / Revised: 27 May 2014 / Accepted: 29 May 2014 # Springer-Verlag Berlin Heidelberg 2014

Abstract Timely recognition of deterioration of hospitalised children is important to improve mortality. We developed a modified Paediatric Early Warning Score (PEWS) and studied the effects by performing three different cohort studies using different end points. Taking unplanned Paediatric Intensive Care Unit admission as end point and only using data until 2 h prior to end point, we found a sensitivity of 0.67 and specificity of 0.88 to timely recognise patients. This proves that earlier identification is possible without a loss of sensitivity compared to other PEWS systems. When determining the corresponding clinical condition in patients with an elevated PEWS dichotomously as ‘sick’ or ‘well’, this resulted in a total of 27 % false-positive scores. This can cause motivational problems for caregivers to use the system but is a consequence of PEWS design to minimise false-negative rates because of high mortality associated with paediatric resuscitation. Using the need for emergency medical interventions as end point, sensitivity of PEWS is high and it seems, therefore, that it is also fit to alert health-care professionals that urgent interventions may be needed. Conclusion: These data show the effectiveness of a modified PEWS in identifying critically

Communicated by Patrick Van Reempts J. Fuijkschot (*) : B. Vernhout : J. M. T. Draaisma : J. L. C. M. Loeffen Department of Paediatrics, Radboudumc Amalia Children’s Hospital, PO box 9101, 6500 HB Nijmegen, The Netherlands e-mail: [email protected] J. Lemson Department of Intensive Care, Radboudumc Amalia Children’s Hospital, PO box 9101, 6500 HB Nijmegen, The Netherlands J. L. C. M. Loeffen Institute for Warranted Quality and Patient Safety, Radboudumc Amalia Children’s Hospital, PO box 9101, 6500 HB Nijmegen, The Netherlands

ill patients in an early phase making early interventions possible and hopefully reduce mortality. Keywords Paediatric Early Warning Score (PEWS) . Rapid response systems . Early interventions . Situational awareness Abbreviations PEWS PICU SA SSE

Paediatric Early Warning Score Paediatric Intensive Care Unit Situational awareness Serious safety event

Introduction Vital parameters of hospitalised patients may deteriorate due to several reasons and subsequently require emergency interventions or intensive care treatment. Early detection of deterioration coupled to effective interventions will likely improve outcome. In the past decade, adult medicine has developed several early warning scoring systems and rapid response systems in order to improve recognition of clinical deterioration in hospitalised patients, thereby improving outcome. Validation studies have shown their effectiveness in identifying patients at risk for serious safety events (SSEs); however, its effect upon reducing overall mortality has yet to be determined [10, 14]. In paediatrics, early recognition of deterioration of vital parameters of hospitalised children is challenging because of the age-related range of reference vital parameters. Hence, the implementation of an unequivocal Paediatric Early Warning Score (PEWS) may improve early recognition and situational awareness amongst health-care professionals.

Eur J Pediatr

A frequently quoted clinically validated PEWS system has been designed by Parshuram and colleagues [11]. This scoring system which is based on seven vital parameters was prospectively validated in three Canadian and one UK children’s hospital. Other, comparable PEWS systems validated in the West-European setting are referred to as the Brighton and Cardiff PEWS [1, 6]. Most systems have been validated retrospectively and suffer from missing data caused by incomplete scores. Still, when defining cardiopulmonary arrest or unplanned Paediatric Intensive Care Unit (PICU) admission as end points, these systems have shown to detect critically ill children at least minutes to 1 h prior to reaching these end points [1, 6, 13, 15]. These scoring systems therefore seem to be useful clinical tools. Most early warning systems are designed to predict the risk for cardiopulmonary arrest or unplanned PICU admission. However, warning systems that also identify the need for emergency medical interventions in an early phase enable health-care professionals to respond earlier and possibly reverse clinical deterioration, thereby preventing unplanned PICU admission. In the Netherlands, experience with regard to fully implemented PEWS systems was lacking. We decided to design and implement a PEWS system that was specified to our setting and which was constructed using latest insights from both paediatric and adult warning systems. Subsequently, we studied its effects upon several patient groups.

Aims and objectives The aim of this study is to show the additional value of PEWS systems in clinical practice towards patient safety and healthcare quality. Objectives are to validate this PEWS system for its applicability in timely identification of ‘sick’ patients (using different end points) and to study its capacity to identify the need for emergency medical interventions.

Method Setting The Radboudumc Amalia Children’s Hospital is a tertiary referral university hospital with three paediatric wards adding up to a total of 77 beds and is located in the Eastern part of the Netherlands. Yearly, it receives an average of 4,000 admissions at these wards where patients get highly specialised care from a broad spectrum of surgical and non-surgical hospital specialists. The same group of nurses with standardised paediatric qualifications and training cares for the patients. In case of clinical deterioration of patients, monitoring of vital norm parameters as well as various emergency medical

interventions (such as a fluid challenge or supplemental oxygen, etc.) can be performed in the ward. In case of further deterioration towards a critically ill state, patients can be transferred to a 10-bed, full facility PICU. PEWS design and implementation From 2011, a modified PEWS system was implemented on all three paediatric wards. This scoring system was based on the data from the Parshuram study. Strikingly however, despite evidence that fever is an important factor in the prediction of paediatric sepsis, neither the Parshuram scoring system nor the Brighton PEWS includes body temperature [8, 16]. Data from adult warning systems show the importance of temperature as a key physiological parameter in predicting clinical deterioration [5]. We therefore decided to add temperature to our scoring system (addition of maximal 2 points to the total score of a patient) expecting to increase PEWS performance, especially in sepsis. Other minor adjustments were made to adapt the system to our setting and to improve user-friendliness. These included a simplified definition of work of breathing (normal or mildly, moderately, severely increased) and supplemental oxygen (room air, low-flow or high-flow supplemental oxygen). Operational proceedings for staff regarding usage of the scoring system in clinical practice were defined. This resulted in an eight-parameter-based bedside PEWS system with a possible scoring range of 0–28 points. All patients admitted to the paediatric wards are routinely scored every 8 h unless their clinical condition deteriorates in which case the frequency of scoring is intensified. A score of 0–3 indicates no specific actions from nursing staff. At a score of 4–7 points, the scoring frequency is automatically increased, and if the score exceeds 7, the nursing staff is instructed to immediately contact the medical team enabling it to promptly identify potential clinical deterioration and treat accordingly. The threshold was chosen based upon the data from the Parshuram study (threshold of 7 points to identify children at risk of cardiopulmonary arrest; corresponding sensitivity 0.64 and specificity 0.91) and the addition of an extra parameter (body temperature) to our scoring system. For each age category, a separate card was developed (0–3 months/3 months–1 year/1–4 years/4– 12 years/≥12 years). An example of one card is given in Fig. 1. Study design and participants To study the performance of our warning system in general and in selected patient cohorts, we performed three different case cohort studies focusing on both the timely identification of ‘sick’ patients (case cohort studies 1 and 2) and identification of patients in need for emergency medical interventions (case cohort study 3).

Eur J Pediatr Fig. 1 PEWS card for age category 3 months–1 year

Paediatric Early Warning Score Age: 3 months – 1 year Score Respiratory rate (breaths/min) Respiratory effort*

4 < 15

Pulse saturation in room air Supplemental oxygen Heart rate (bpm) Capillary refill time (sternum) Systolic blood pressure (mmHg) Temperature (°C)

2 15-19

90

normal

mildly ↑

moderate ↑

severely ↑ or apnoeic

NRB-mask

>94% Room air

38.5 * respiratory effort: nasal flaring or retracons

Standard: Scoring frequency 1x per 8 hours| PEWS 3x 0-2: reduce scoring frequency to 1x per day PEWS score ≥ 4 points or worried sign: increase PEWS frequency to 1x per 4 hours PEWS score ≥ 6 points: increase PEWS frequency to 1x per hour PEWS score ≥ 8 points: contact aending physician within 10 minutes or call PMET PMET dial pager 2148 | Resuscitaon dial 55555

Identification of sick patients

Identification of need for critical care type interventions

Case cohort study 1 This study was performed to test the scoring system’s general ability to identify sick patients. Correlation between warning score and severity of illness was studied by performing a retrospective database review of early warning scores in all patients admitted at the 20-bed paediatric oncology ward over a 3-month period. The study was performed on this ward because it was the very first at which PEWS was implemented in 2011 and also because of the clinical nature of paediatric oncology patients. Though their physiological responses may differ from other patients, it was expected that a higher number of sick patients could be encountered at this ward, thereby improving chances of successful validation. Focus was on the clinical condition of patients with alarming high scores (≥8). In addition, the effects of the added body temperature parameter upon the scores were studied in both patients with alarming high scores and a randomly selected control group consisting of one third of the patients with PEWS