The search yielded 469 articles in the PubMed, Cochrane/ EBM Reviews, Embase, Global Health and Dissertations &Theses Global databases. 360 studies were excluded according to their title, 16 because they were duplicated and 78 for not meeting the selection criteria -32 were conducted outside Canada or Europe, 27 did not evaluate any screening tool, 11 were secondary studies (reviews), 4 included adult patients and 4 were incomplete or in another language. The final sample consisted of 15 studies.

Table 2 compiles and integrates the information from the 15 studies included in the literature review according to the PICO characteristics of the research. ^26-40 It should be noted that, although the search included original studies published between 2002 and 2017, the selected articles were released between 2010 and 2017 (67% of them were published between 2012 and 2017), thus indicating that the results are up-to-date. All studies were developed in European countries.

Table 2

STAMP: Screening Tool for the Assessment of Malnutrition in Paediatrics; STAMPm adaptation of the original STAMP tool, in which the UK growth charts were replaced by the Spanish growth charts; PMST: Paediatric Malnutrition Screening Tool; PYMS: Paediatric Yorkhill Malnutrition Screening; WHO: World Health Organization; STRONGkids: Screening Tool for Risk of Impaired Nutritional Status and Growth; PeDiSMART: Pediatric Digital Scaled Malnutrition Risk Screening Tool; PNR: Paediatric Nutritional Risk; iPYMS: Infant Paediatric Yorkhill Malnutrition Score; TPH: tertiary pediatric hospital; DGH: district general hospital.

Seven tools have been validated in European countries for the identification of pediatric patients at nutritional risk: Paediatric Yorkhill Malnutrition Screening (PYMS), Infant Paediatric Yorkhill Malnutrition Score (iPYMS), Pediatric Digital Scaled Malnutrition Risk Screening Tool (PeDiSMART), Paediatric Nutritional Risk (PNR), Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP), Paediatric Malnutrition Screening Tool (PMST) and Screening Tool for Risk of Impaired Nutritional Status and Growth (STRONGkids). All were designed to be used during hospital admission and, except for PNR, have the possibility of being used again after the first week of hospital stay.

Table 3 shows a comparison between the different nutritional screening tools, taking into account the four variables that must be incorporated to correctly identify the nutritional risk of hospitalized patients.^21,22

Table 3

STAMP: Screening Tool for the Assessment of Malnutrition in Paediatrics; PMST: Paediatric Malnutrition Screening Tool; PYMS: Paediatric Yorkhill Malnutrition Screening; iPYMS: Infant Paediatric Yorkhill Malnutrition Score; STRONGkids: Screening Tool for Risk of Impaired Nutritional Status and Growth; PNR: Paediatric Nutritional Risk; PeDiSMART: Pediatric Digital Scaled Malnutrition Risk Screening Tool.

Considering the statistical data extracted from the included studies, concurrent validity and reproducibility were the basis of the analysis of the nutritional screening tools validity since they are commonly found in most studies. This allows comparing most of the identified nutritional screening instruments.

Table 4 presents the included studies that evaluate the concurrent validity of 5 pediatric nutritional screening tools (STAMP, PMST, PYMS, iPYMS and STRONGkids). In turn, Table 5 depicts the studies that included results on concordance among observers where it was considered sufficient for Kappa values >0.41.⁴¹

Table 4

STAMP: Screening Tool for the Assessment of Malnutrition in Paediatrics; PMST: Paediatric Malnutrition Screening Tool; PYMS: Paediatric Yorkhill Malnutrition Screening; STRONGkids: Screening Tool for Risk of Impaired Nutritional Status and Growth; iPYMS: Infant Paediatric Yorkhill Malnutrition Score; WHO: World Health Organization.

Table 5

PeDiSMART: Pediatric Digital Scaled Malnutrition Risk Screening Tool; STRONGkids: Screening Tool for Risk of Impaired Nutritional Status and Growth; STAMP: Screening Tool for the Assessment of Malnutrition in Paediatrics; PYMS: Paediatric Yorkhill Malnutrition Screening.

The level of certainty was estimated for 67% of the studies, as they included results assessing concurrent validity (in terms of sensitivity and specificity) and reproducibility (in terms of inter-observer agreement). The remaining 33% yielded other results such as predictive validity and intra-rater reliability, which were not analyzed because of the total number of articles with data, time and resources. ^{27,32,34,36,39}

Among the 10 studies for which the level of certainty was calculated, the Chourdakis et al³⁸ study had the highest level of certainty, mainly because it was carried out in 12 countries throughout Europe with a sample of 2 567 patients and because the results were consistent. In contrast, the level of certainty of the study by Thomas et al.,²⁶ which was carried out in the United Kingdom, was considered low, particularly because it was a unicenter research with convenience sampling and inconsistent results. The remaining 8 studies were classified at a moderate level since they were multicenter studies, with randomized, systematized or consecutive sampling and generally consistent results that allow, to some extent, the generalization of findings to clinical practice.^{28-31,33,35,38,40}

Of the seven tools identified in this systematic review, quality assessment was only possible in six of them, namely, PYMS, iPYMS, STAMP, PMST, STRONGkids and PEDISMART. A complete quality analysis -i.e. concurrent validity and reproducibility- was conducted only for the STAMP, PYMS and STRONGkids, while in the case of iPYMS and PMST only concurrent validity was evaluated, and for the PEDISMART tool, only reproducibility was assessed.

The partial evaluation of the PEDISMART, PNR and iPYMS tools does not mean that they are not useful in other contexts or situations; it means that there is no information on the characteristics that were considered of greater relevance in those reviews. Table 6 presents recommendations for the use of validated nutritional screening tools in European children according to concurrent validity and reproducibility characteristics.

Table 6

PYMS: Paediatric Yorkhill Malnutrition Screening; STAMP: Screening Tool for the Assessment of Malnutrition in Paediatrics; iPYMS: Infant Paediatric Yorkhill Malnutrition Score; STRONGkids: Screening Tool for Risk of Impaired Nutritional Status and Growth; PeDiSMART: Pediatric Digital Scaled Malnutrition Risk Screening Tool; PMST: Paediatric Malnutrition Screening Tool.

Based on the ESPEN guidelines described in Table 3, only the PYMS tool for screening patients between 1 and 16 years of age hospitalized in floors and surgical areas, the iPYMS for the same type of population but under 2 years of age, and the STRONGkids for the same type of population with ages between 1 month and 18 years of age, evaluate all the variables that are considered to have a nutritional impact. To this end, they assess current nutritional status, weight loss, reduced intake and severity of disease (Table 2). ⁽²¹

Thus, the PYMS, iPYMS and STRONGkids tools can be considered as the most suitable tools for nutritional screening. However, these are not the only criteria that must be considered to state that a tool is appropriate since any screening tool can be used to identify children with or at risk of malnutrition, as long as the results translate into early intervention and improved clinical outcomes.

Nutritional screening is a tool that is classified into the same category of diagnostic tests, which means that it is an instrument that allows obtaining additional information about a patient in order to adequately define the care plan to be followed. ⁴² Moreover, the use of nutritional screening tools is relevant for care centers since their routine use allows the optimization of economic and human resources and the reduction of costs derived from hospital malnutrition. ^21,43 In this sense, and given that a highly sensitive tool is designed to correctly detect a greater proportion of patients at real nutritional risk -i.e. those who require greater monitoring of their nutritional status-, the most important statistic is sensitivity. ⁴⁴

Although the screening tools were validated using different reference methods (Table 2), if sensitivity (ability to detect true positives) >85% is considered as acceptable, the PYMS, iPYMS and PMST tools may be the best options for screening, followed by STAMP with adequate but less consistent sensitivity according to the studies analyzed. However, if good specificity (ability to detect true negatives) is also considered as a desirable characteristic, only the PYMS tool meets these two characteristics of concurrent validity. ^35,39

It should be noted that these results are not consistent across studies, ²⁶ partly because sensitivity and specificity tend to be inversely related. ⁴⁵ In this regard, the meta-analysis by Huysentruyt et al.,⁴⁶ by including gold standards to validate the tools, shows that there is a marked variation among the studies included. Consequently, in order to have more consistent results, it is necessary to establish a gold standard to assess sensitivity and specificity and to obtain results with greater comparability between studies.

Reproducibility was also assessed, as good agreement between raters in a nutritional screening tool is desirable. The results showed that the PeDiSMART, STRONGkids, STAMP, and PYMS tools have acceptable inter-observer agreement when assessing reproducibility across a broad spectrum of health professionals (Table 5). This is relevant given that a good nutritional screening tool should require little training of clinical staff to complete the instrument and should be quick to use and interpret thanks to a simple scoring system. ²³

Table 6 presents recommendations for the use of the PYMS, STAMP, iPYMS, STRONGkids, PeDiSMART and PMST tools according to desirable characteristics such as concurrent validity and reproducibility. Nevertheless, it should be remembered that these are not the only characteristics to consider; ease of use, the time required, and predictive validity should also be considered, ²³ although that was not the case of this paper due to the limited information available. Even so, it is expected that the results reported here will help health staff choose the best option for nutritional screening in pediatrics from the tools available for implementation in institutional protocols.

The present review is limited by geographical demarcation to only Canada and Europe, so this work should be complementary to other reviews carried out outside the proposed context. ^22,47 Another limitation is that this study focuses on screening tools that determine the risk of malnutrition; however, these tools can be modified (especially the current nutritional status variable) to detect overweight, which can also have negative consequences in hospitalized children.

On the other hand, although the quality of the included studies was evaluated, bearing in mind that this review aims to summarize the available evidence, it is not exempt from the systematic errors of the designs of the original studies; therefore, the work was carried out according to the PRISMA statement to include all the available studies and minimize selection bias. ^48,49 Finally, due to the lack of international consensus on the definition of malnutrition, there is no standard reference for assessing the validity of nutritional screening tools with the same method; this makes the results of the tools closely linked to the classification of malnutrition in each study. Therefore, once a universal diagnosis for malnutrition is established, it is expected that tool validation studies will yield more consistent results.