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Recommendations Summary

CF: Assessment of Energy Requirements 2020

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.

  • Recommendation(s)

    CF: Indirect Calorimetry

    In pediatric (≤20 years of age) and adult individuals with cystic fibrosis (CF), it is reasonable for the RDN or international equivalent to measure energy needs using indirect calorimetry, when feasible and indicated, since indirect calorimetry is the gold standard for measuring energy expenditure in clinical settings. 

    Rating: Consensus

    CF: Estimating Energy Needs, Pediatrics

    In pediatric individuals with cystic fibrosis (CF) ≤20 years of age, the RDN or international equivalent may estimate energy needs at each nutrition assessment using the recommonded dietary allowance (RDA) or Institute of Medicine (IOM) active lifestyles formulas, since these formulas were the most accurate compared to indirect calorimetry in this population. Energy needs should be individualized based on growth history, nutrition status,  medications, physical activity, and disease severity.

    Rating: Weak

    CF: Estimating Energy Needs, Adults

    In adults with cystic fibrosis (CF) greater than 20 years of age, the RDN or international equivalent may estimate energy needs annually or with unintentional weight changes using standard energy expenditure equations x 1.25, since estimated energy requirements for the general population may underestimate needs in adults with CF.  Energy needs should be individualized based on nutrition status, medications, physical activity, and disease severity.

    Rating: Weak

    • Risks/Harms of Implementing This Recommendation

      Energy prescriptions that are too high or too low may affect nutrition status and, therefore, disease severity. However, routine nutrition screening can identify if and when energy prescriptions may need to be altered.

    • Conditions of Application

      Energy expenditure is typically only be estimated, not measured, in clinical practice. When direct measurement by indirect calorimetry is available and feasible, measurement of energy expenditure may be indicated for individuals on enteral or parenteral nutrition, those struggling to maintain weight/growth or according to patient preference. While indirect calorimetry can be conducted in pediatric clients, it may be difficult for them to cooperate for the duration of the procedure. These recommendations provide a starting point for estimating energy requirements, but will not be completely accurate for every individual with CF. Energy estimates may be decreased for those on certain medications (ex: CFTR modulation therapy) or with concerning increasing trends in weight and will need to be increased for those with concerning decreasing trends in weight/growth, and with physical activity. Increasing disease severity, including exocrine pancreatic insufficiency, may increase energy needs. Needs will also be increased to account for refeeding with severe malnutrition and initially following lung transplant. Once an individual is stabilized and discharged following transplant, however, energy needs may decrease (Brooks et al 1995, Alpers et al 1999, Marik et al 1996, Afzal et al 2002, Solomon et al 1990). RDNs should individualize energy prescription by adjusting estimates according to growth and weight trends, individual disease status (including overweight/obesity), extent of malabsorption and physical activity. Ultimately, weight loss or gain is the gold standard for increasing or decreasing energy prescription.

    • Potential Costs Associated with Application

      Measurement of energy expenditure with indirect calorimetry may be cost-prohibitive, and RDNs should consider costs and benefits when determining if this method should be used. There are no obvious costs associated with the recommendations for estimating energy needs.

    • Recommendation Narrative

      Background. Energy requirements are highly individual for persons with cystic fibrosis (CF) and vary according to disease severity, including pancreatic insufficiency and PERT, transplant status and other factors. Using the most accurate equations is essential in order to reasonably estimate energy requirements and, therefore, advise individuals on dietary goals.

      Evidence for pediatrics. In one study of children with CF who were primarily pancreatic insufficient, CF-specific energy equations over-estimated needs (122-136%) compared to doubly labeled water. Energy expenditure estimated with the IOM active lifestyle formula and RDA were similar to measured values, though these equations did not adjust for individuals’ activity level. Evidence was only available for 6-20-year-old children and adolescents and, thus, may not be generalizable to younger children (Moudiou et al 2007, Moudiou et al 2007, Trabulsi et al 2007).

      Evidence for adults. In adults with end-stage CF, Harris-Benedict, Schofield and WHO 1985 energy expenditure equations underestimated energy needs compared to indirect calorimetry (76-78% in pre-lung transplant and 90-91% in post-lung transplant). Underestimation was greater in those with more severe disease (Moudiou, Galli-Tsinopoulou, Vamvakoudis, Nousia-Arvanitakis 2007, Moudiou et al 2007, Hollander et al 2017).

    • Recommendation Strength Rationale

      These recommendations are based on Grade III, or Limited/Weak evidence. Therefore, further research may result in changes to the above recommendations.

    • Minority Opinions

      Consensus reached.