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Principles of Paediatric Dietetics: Nutritional Assessment, Dietary Requirements and Feed Supplementation

Vanessa Shaw and Helen McCarthy

Introduction

This text provides a practical approach to the dietary management of a range of paediatric disorders. The principles outlined in this chapter are relevant to all infants, children and young people and provide the basis for many of the therapies described later in the text. Chapter 2 describes healthy eating throughout childhood and adolescence to support normal growth and development and may inform dietetic interventions; special considerations for children from minority ethnic groups are addressed in Chapter 26. The remaining text focuses on nutritional requirements and management in the clinical setting, illustrating how normal dietary constituents are used alongside special dietetic products to allow for the continued growth of the child while controlling the progression and symptoms of disease.

Assessment of nutritional status

Assessment and monitoring of nutritional status should be included in any dietary regimen, audit procedure or research project where a modified diet has a role. Although the terms are used interchangeably in the literature, nutrition screening is a simple and rapid means of identifying individuals at nutritional risk, which can be undertaken by a range of healthcare professionals, whereas nutrition assessment is a more detailed and lengthy means for nutrition experts, i.e. dietitians, to quantify nutritional status.

Nutrition screening

While nutrition screening tools can be used to identify all aspects of malnutrition (excess, deficiency or imbalance in macro‐ and micronutrients), they are generally used to identify protein–energy undernutrition [1]. Despite the recommendations from benchmark standards and national and international guidelines that screening for nutrition risk be an integral component of clinical care for all [2–5], the development of nutrition screening tools for use with children has lagged behind work in the adult world. However, internationally, a number of child‐specific nutrition screening tools have been developed including the Nutrition Risk Score (Paris tool), the Subjective Global Nutrition Assessment (SGNA), StrongKids and the Paediatric Nutrition Screening Tool (PNST) [6–9]. Each of these has strengths and limitations in terms of validity and reliability of the tool, the time taken to complete and the level of skill required by individuals applying the tool.

Two child‐specific tools have been developed in the UK: the Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP) and the Paediatric Yorkhill Malnutrition Score (PYMS) [10, 11]. Both of these tools have been evaluated in practice and comprise a number of elements that are scored to give a final risk score (Table 1.1). The reliability of each of these tools has been published, along with a number of other studies evaluating their use in a variety of clinical settings and conditions [12–14]. The main limitation of these evaluation studies is that they rely on the dietetic assessment of nutritional status as the ‘gold standard’, and the findings of studies comparing the tools to date have been equivocal. A large multicentre Europe‐wide study under the auspices of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) has evaluated STAMP, PYMS and StrongKids in 14 centres across 12 countries. The results found only modest agreement between the three tools in identifying children at high malnutrition risk, with PYMS and STAMP classifying more children in this category than StrongKids. The authors concluded that there was still much work needed in this area and that none of the three tools evaluated could be recommended for routine clinical practice [15–17].

Table 1.1 Child‐specific screening tools developed and evaluated in the UK.

STAMP

PYMS

Criteria utilised

Diagnosis Dietary intake Anthropometrics: weight and height centile

Diagnosis Dietary intake Weight loss Anthropometrics: BMI

Scored

High/medium/low risk

High/medium/low risk

Criterion validity

Agreement with full nutritional assessment*

54%

46%

Positive predictive value†

55%

47%

Negative predictive value††

95%

95%

Training

30 minutes

60 minutes

Used by

Any trained healthcare professional

Registered nurses

STAMP, Screening Tool for the Assessment of Malnutrition in Paediatrics; PYMS, Paediatric Yorkhill Malnutrition Score; BMI, body mass index.

* Children identified as being at nutritional risk by tool and full nutritional assessment.

† The proportion of children identified as at risk by the tool who are actually at risk.

†† The proportion of children identified as not at risk by the tool who are actually not at risk.

Nutritional assessment

Nutritional assessment comprises anthropometric, clinical and dietary assessment, all of which should be used to provide as full a picture of the nutritional status of the individual as possible; no one method will give an overall picture of nutritional status. Within these areas there are several assessment techniques, some of which should be used routinely in all centres, while others are better suited to specialist clinical areas or research. This chapter provides a brief overview of the common techniques and sources of further information.

Anthropometry

Measurement of weight and height (or length) is critical as the basis for calculating dietary requirements as well as monitoring the effects of dietary intervention. It is important that all measurements are taken using standardised techniques and calibrated equipment. Ideally staff taking measurements should receive some training on how to do this accurately. There are a variety of online resources to support training in anthropometric measurement of children.

Weight

Measurement of weight is an easy and routine procedure that should be done using a calibrated digital scale. Ideally infants should be weighed naked and children wearing just a dry nappy or pants; however, this is often not possible or appropriate. In these situations, it is important to record if the infant is weighed wearing a clean dry nappy and the amount and type of clothing worn by older children. A higher degree of accuracy is required for the assessment of sick children than for routine measurements in the community. Frequent weight monitoring is important for the sick infant or child, and local policies for weighing and measuring hospitalised infants and children should be in place. Recommendations for the routine measurement of healthy infants where there are no concerns about growth are given in Table 1.2 [18]. If there are concerns about weight gain that is too slow or too rapid, measurement of weight should be carried out more frequently.

Table 1.2 Recommendations for routine measurements for healthy infants and children.

Source: Adapted from Hall [18] and NICE PH11 [19].

Weight

Length/height

Head circumference

Birth

Birth

Birth or neonatal period

In the first week of life as part of overall assessment of feeding

8 weeks

6−8 weeks if birthweight <2.5 kg or if other cause for concern

6−8 weeks

12 weeks

16 weeks

1 year

Additional weights if there are concerns: not more frequently than once a month for infants <6 months; once every 2 months from 6 to 12 months; once every 3 months over 1 year

No other routine measurement of length/height

No other routine measurement of head circumference

School entry

School entry

Height

Height or length measurement requires a stadiometer or length board. Measurement of length using a tape measure is too inaccurate to be of use for longitudinal monitoring of growth, although an approximate length may be useful as a single measure. Under the age of 2 years, supine length is measured; standing height is usually measured over this age or whenever the child can stand straight and unsupported. When the method of measurement changes from length to height, there is likely to be a drop in stature; this is accounted for in the UK‐WHO growth charts (p. 3). Measurement of length is difficult and requires careful positioning of the infant; positioning of the child is also...