CF: Nutrition Screening: Adults 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.
CF: Frequency of Nutrition Screening, Adults
In adults with cystic fibrosis (CF) greater than 20 years of age, it is reasonable to measure weight and height at each clinic visit and to screen for malnutrition and/or other nutrition concerns at least quarterly or more frequently based on clinical condition to identify nutrition risk.
CF: Method of Nutrition Screening, Adults
Adults with cystic fibrosis (CF) greater than 20 years of age should be screened for nutrition risk by evaluating absolute values and trends in BMI, since BMI is longitudinally associated with lung function. Women who have a BMI <22 kg/m2, men who have a BMI <23 kg/m2, or adults who have concerning trends in BMI (either decreasing or increasing) should be referred for full nutrition assessment by an RDN or international equivalent.
Risks/Harms of Implementing This Recommendation
There are no obvious risks or harms associated with nutrition screening recommendations.
Conditions of Application
RDN Judgement. These recommendations should be interpreted and implemented with consideration of client history and goals. The recommendation regarding the criteria for referring adult clients for full nutrition assessment is based on research describing the inverse relationship between weight and disease progression. However, many adults will naturally fall beneath the BMI cut points. When monitoring clients, RDNs must use clinical judgement to determine if adults with BMI scores under these cut-offs are actually at nutrition risk or if they are stable at a lower BMI and assessment is not needed. While drastic increases or decreases in BMI will nearly always be an indication for full assessment, this process may or may not be possible at any given time depending on the other health concerns the client is managing.
Healthcare Practitioner conducting Nutrition Screening. Though RDNs may not see or counsel individuals with CF and their families at every clinic visit, BMI should be measured at each clinic visit, and RDNs, dietetic technicians registered (DTRs) or other qualified healthcare professionals should be responsible for monitoring trends in BMI to identify nutrition risk. If the RDN is not the individual screening for nutrition status, healthcare facilities should adopt a timely and reliable system for alerting RDNs when BMI measures warrant full nutrition assessment.
Special Needs. Methods of measuring height and weight may vary according to the needs of the client and RDNs may utilize methods such as using sling weight or incremental length when appropriate.
Training. All persons conducting weight, height measures should be adequately trained using an institution-specific standardized protocol and appropriate and calibrated measurement tools (scale).
Potential Costs Associated with Application
Measuring weight and height requires minimal resources (scale and stadiometer) beyond those needed in any other standard practice. Equipment must be properly maintained and calibrated.
In adults with cystic fibrosis (CF), data was mixed, but one large retrospective cohort study suggested that BMI ≥ 25 kg/m2 was associated with decreased decline in FEV1% predicted, and BMI <18.5 kg/m2 was associated with increased decline in FEV1% predicted compared to normal weight status after a follow-up of up to 13 years (Goss et al 2018). Baseline FEV1% predicted was also associated with change in BMI over time (Goss et al 2018), so it is likely that the relationship between weight parameters and lung function is bi-directional.
In adults with CF, unfortunately there was no included literature examining health outcomes according to BMI cut-offs recommended by the CF Foundation: 22 kg/m2 for women and 23 kg/m2 for men. However, evidence did demonstrate that using a BMI cut-off of ≤18.5 kg/m2 to identify malnutrition in adults with CF may misclassify those who have a BMI higher than 18.5 kg/m2 but are malnourished based on low fat free mass.(Hollander et al 2014, King et al 2010) There is no literature available to suggest that individuals with CF are exempt from overweight or obesity related co-morbidities such as type II diabetes, cardiac disease, or hypertension.
Recommendation Strength Rationale
The recommendation for adult participants is based off of Grade II, or fair, evidence indicating the longitudinal relationship between specific weight parameters and lung function and mortality as well as clinical experience and norms in clinical practice, guided by the CF Foundation (Cystic Fibrosis Foundation 2019).
- Risks/Harms of Implementing This Recommendation
The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).
In adults with CF, what is the longitudinal relationship (at least 3 months) between weight parameters and FEV1?
In adults with CF, which weight parameters are valid and reliable compared to reference standards, as measured by validity and/or reliability studies?
Goss C, Sykes J, Stanojevic S, Marshall B, Petren K, Ostrenga J, Fink A, Elbert A, Quon B, Stephenson A. Comparison of nutrition and lung function outcomes in [atients with cystic fibrosis living in Canada and the United States. American Journal of Respiratory and Critical Care Medicine 2018; 197:768-775
Hollander F, van Pierre D, de Roos N, van de Graaf E, Iestra J. Effects of nutritional status and dietetic interventions on survival in Cystic Fibrosis patients before and after lung transplantation. Journal of Cystic Fibrosis 2014; 13:212-8
King S, Nyulasi I, Strauss B, Kotsimbos T, Bailey M, Wilson J. Fat-free mass depletion in cystic fibrosis: associated with lung disease severity but poorly detected by body mass index. Nutrition (Burbank, Los Angeles County, Calif.) 2009; 26:753-9
References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process
Cystic Fibrosis Foundation. Nutritional Basics. Cystic Fibrosis Foundation. https://www.cff.org/Life-With-CF/Daily-Life/Fitness-and-Nutrition/Nutrition/Getting-Your-Nutrients/Nutritional-Basics/. Accessed September 25, 2019.