Issue 126 cystic fybrosis nutritional strategies and management

CONDITIONS & DISORDERS

Jacqui Lowdon Paediatric Dietitian, RMCH Presently team leader for Critical Care and Burns, Jacqui previously specialised in gastroenterology and cystic fibrosis.

Although her career to date has focused on the acute sector, Jacqui has a great interest in paediatric public health.

For full article references please email info@ networkhealth group.co.uk

CYSTIC FIBROSIS: NUTRITIONAL STRATEGIES AND MANAGEMENT It is well documented that optimal growth and nutrition in children with cystic fibrosis (CF) is crucial to maintain health and lung function.1-3 Lung disease and nutritional status are closely related4 and so, both are strong predictors of morbidity and mortality.5-7 It is essential that this patient group is assessed and monitored on a routine basis to help identify the most appropriate nutritional strategies and assess their outcomes. Debate has ensued, however, as to the best measures to use in order to assess growth in patients with CF, in view of recently published guidelines.

There is then the struggle to maintain the optimal nutritional status and how best to achieve this.

ASSESSMENT OF GROWTH

In CF, nutrition is considered to be adequate when growth is similar to that of an age-matched healthy population.8 It is, therefore, paramount that growth in children with CF is closely monitored.

Appropriate growth charts should be used, according to the nationality and ethnicity of the child. In the absence of those, the World Health Organisation (WHO) growth charts should be used.

In a busy clinical setting, Body Mass Index (BMI), being quick and simple to calculate, is accepted as being the most appropriate measure of nutritional status in children with CF over the age of two years. (BMI cannot be used in children under the age of two years, as there are no reference values for BMI percentiles (BMIp) for this age group.9-11)

BMI determines whether weight is in the appropriate range for height. In children, BMIp has been reported to be a more sensitive marker of nutritional failure than other weight and height based measures such as percentage ideal body weight.12 In children over the age of two years, a BMIp of less than or equal to the 20th percentile is associated with a reduced lung function and low bone mineral density, compared to a BMIp greater or equal to the 50th percentile which is associated with better lung function.1,9 The US Cystic Fibrosis Foundation (CFF) and the European CF Society both emphasise the use of BMI percentile for older children and adolescents, aged two to 20 years, with a BMI target at or above the 50th percentile for healthy children.8,9 The CFF Consensus Report criteria defines nutrition-related compromise as BMI <C10th, nutritional risk BMI C10th25th and acceptable nutritional status BMI >C25th.13 However, as BMI adjusts for height, this can mask nutritional stunting and so it must not be used in isolation in growing children. It is still important to review any change in height percentile/ SD score.14-16 Pubertal delay may also affect BMI, so requires consideration when www.NHDmag.com July 2017 - Issue 126

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FROM HOLDING BACK.. . .TO HOLDING JACK

. .In a shot SOMETIMES PATIENTS CAN’T MEET THE ENERGY REQUIREMENTS THEY NEED THROUGH NORMAL DIET AND ONS ALONE.1

IT’s BEEN SHOWN TO:

Little wonder it helps so much

55% 92% 67%

Increase calorie intake by 55% IN ADDITION TO NORMAL diet 2 HAVE 92% COMPLIANCE OF THE PRESCRIBED DAILY AMOUNT3 Reduce ‘MUST’ scoreS IN 67% OF PATIENTS*3,4

Pro-Cal shot is a food for special medical purposes and should be used under strict medical supervision. ® Reg. Trademarks of Société des Produits Nestlé S.A.

®

Vitaflo International Ltd, Suite 1.11, South Harrington Building, 182 Sefton Street, Brunswick Business Park, Liverpool L3 4BQ, UK. Tel: 0151 709 9020 vitaflo.co.uk abbottnutrition.co.uk A Nestlé Health Science Company

References 1. Wright C. CN Focus 2012;4(3):17-19. 2. Sharma M et al. Colorectal Disease 2013;15: 885-891. 3. Data on file. 4. Malnutrition Advisory Group (MAG) 2011.Malnutrition Universal Screening Tool. www.bapen.org.uk/pdfs/must/must_full.pdf. Accessed September 2016. *Of those who were at medium or high risk of malnutrition at baseline, 67% were at low risk of malnutrition on study completion.

All information correct at the time of print. December 2016

Table 1: Breakdown of nutritional therapy data from the UK Cystic Fibrosis Registry 2015, Annual Data Report, published August 2016 Overall (n=9587)

<16 years (n=3845)

≥16 years (n=5742)

Any supplemental feeding n(%)

3126 (32.6)

1120 (29.1)

2006 (34.9)

Nasogastric tube

109 (1.1)

15 (0.4)

94 (1.6)

Gastrostomy tube/ button

557 (5.8)

220 (5.7)

337 (5.9)

7 (0.1)

<5

<5

<5

<5

<5

Jejunal TPN

assessing nutritional status and interpretation of growth charts. With delayed puberty, height percentile is initially lost but then catches up when the child enters their delayed growth spurt.

This emphasis on the use of BMI has, however, come in for criticism. Konstan et al17 analysed data from the Epidemiologic Study of CF to compare patient weight for height (WFA), height for age (HFA) and BMIp for 11,769 children aged two to 18 years. The study found that a large number of children with CF who have a BMI at or above the 50th percentile have poor growth or nutritional status based on weight and/or height. In particular, children who were short for their age had relatively raised BMI values. Those with a BMI between the 25th and 50th percentile and who were not considered to be nutritionally ‘at risk’ according to the guidelines, were often found to have a poor nutritional status based on weight and/or height. More than one in six had WFA below the 10th percentile and one in four had HFA below the 10th percentile.

This paper highlights that although achieving a BMI percentile of 50th is desirable, some children with CF who have a BMI at or above the 50th percentile can still demonstrate poor nutritional status when evaluated by weight and height for age. It also highlights the risk of only identifying nutritionally compromised children with a BMI below the 25th percentile and that solely relying on BMI will fail to identify a large number of children with CF who are short and underweight for their age. One criticism of this study is that the measures used were from between 2003 and 2005 and so this needs to be repeated using more recent values. However, it does highlight the need for guidelines to consider the importance of monitoring weight and height for age in addition to BMI.

A recently published and validated nutrition screening tool18 for children with CF, used BMI along with other anthropometric data. This included weight gain/loss/maintenance and height gain/maintenance. The height assessment was based on the last year and also took into consideration pubertal staging. In designing a tool based on progression of nutritional status, a risk was identified in patients who appeared to have acceptable nutritional status but whose weight and height were stationary or increasingly below acceptable levels. This screening tool identified 15 patients as being at nutritionally at risk, who had previously been identified as having ‘acceptable nutritional status’ by the CFF Consensus Report criteria. It, therefore, has higher sensitivity compared to the CFF Consensus Report criteria.

Although this screening tool incorporates other clinical variables to help identify nutritional at risk patients, this higher sensitivity could in part be attributed to being based on progression of nutritional status, analysing weight and height gain over time, rather than solely being based on BMI. NUTRITIONAL STRATEGIES

It can be a struggle to achieve and/or maintain optimal nutritional status, even from early on in life for children with CF. Dietary counselling, oral nutritional supplements, maximising absorption, behavioural modification and enteral tube feeding (ETF) are all strategies that can be used to aid weight gain and growth in CF. Table 1 shows a breakdown of nutritional therapy data from the UK Cystic Fibrosis Registry 2015.

There is, however, a lack of good quality studies to assess the effectiveness of some of these strategies. Vered et al19 reviewed the randomised control trials that addressed nutritional www.NHDmag.com July 2017 - Issue 126

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CONDITIONS & DISORDERS

Once undernutrition has been identified, there are a number of nutritional strategies that can be employed to improve nutritional status interventions in patients with CF. They found 51 randomised control trials, but only a minority provided the full methodology; they had small patient numbers with no sample size calculations; the mean intervention period was short, only six months and more than half did not define a primary outcome. They also highlighted the lack of outcomes that are important to the patient.

ENTERAL TUBE FEEDING

For some children with CF, ETF can be useful in achieving the desired optimal nutritional status.

Current UK and European guidance, however, does not include detailed recommendations for ETF. Although there are small single centre multiple retrospective studies demonstrating that ETF can improve age dependent measures of growth, such as weight/age percentile, length/ age percentile, weight for height percentile and BMI and suggestion of improved lung function, there are no randomised clinical trials.

A recent systematic review23 has assessed the literature published after 1997, describing the effectiveness of nutritional interventions in patients with CF. Seventeen research articles were reviewed, focusing on behavioural interventions (n=6), oral supplementation (n=4) and ETF (n=7). The latter intervention was universally successful at promoting weight gain. One behavioural study and two oral supplementation studies also reported significant weight gain. The review concluded that ETF is effective in improving nutritional status, while the effects of behavioural intervention and oral supplementation are not sufficiently consistent at present. Additionally, ETF is especially effective at improving the nutritional status in malnourished patients and slowing down further pulmonary function decline.

In 2016, the CFF published evidence informed guidelines24 based on a systematic review of the evidence and expert opinion.

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Thirty-three Consensus statements have been recommended. Areas addressed include when to consider ETF, assessment of other influences resulting in poor nutrition, counselling the child and family for placement of ETF, post insertion management of the tube and education on ETF. One area that should be highlighted is the recommendation that the child and family are educated about nutrition, including the role of ETF, throughout their lifetime. Although nutrition is highlighted from the point of diagnosis, all too often ETF discussions take place when all other nutritional options have failed and so families often view it as an option borne out of failure rather than as an alternative, successful option. The CFF highlight the benefits of early introduction of ETF to allow the child and family to be happy with their choice and be inclusive in the decision making.

CONCLUSION

Despite all the evidence that optimal growth and nutrition in children with CF is crucial to maintain health and lung function, the best measures to use in order to assess growth in patients with CF have still to be agreed. Whilst BMIp has been reported to be a more sensitive marker of nutritional failure than other weight and height based measures, it does not take into consideration children who are short for their age and have relatively raised BMI values.

Solely relying on BMI may fail to identify a large number of children with CF who are short and underweight for their age.

Once undernutrition has been identified, there are a number of nutritional strategies that can be employed to improve nutritional status, including ETF. Although there has recently been published evidence informed ETF guidelines, further areas of research are still required in this area.