Nutrition
Volume 26, Issue 7 , Pages 753-759, July 2010

Fat-free mass depletion in cystic fibrosis: Associated with lung disease severity but poorly detected by body mass index

  • Susannah J. King, Ph.D.

      Affiliations

    • Nutrition and Dietetics Unit, Monash University, Monash Medical Centre, Victoria, Australia
    • Department of Medicine, Monash University, Alfred Hospital, Melbourne, Victoria, Australia
    • Nutrition Department, Alfred Hospital, Melbourne, Victoria, Australia
    • Corresponding Author InformationCorresponding author. Tel.: +61-3-9594-4472; fax: +61-3-9594-6509.
    • ,
  • Ibolya B. Nyulasi, M.Sc.

      Affiliations

    • Nutrition and Dietetics Unit, Monash University, Monash Medical Centre, Victoria, Australia
    • Nutrition Department, Alfred Hospital, Melbourne, Victoria, Australia
    • ,
  • Boyd J.G. Strauss, Ph.D.

      Affiliations

    • Nutrition and Dietetics Unit, Monash University, Monash Medical Centre, Victoria, Australia
    • Body Composition Laboratory, Monash Medical Centre, Clayton, Victoria, Australia
    • ,
  • Tom Kotsimbos, M.D.

      Affiliations

    • Department of Medicine, Monash University, Alfred Hospital, Melbourne, Victoria, Australia
    • Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Victoria, Australia
    • ,
  • Michael Bailey, Ph.D.

      Affiliations

    • Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
    • ,
  • John W. Wilson, Ph.D.

      Affiliations

    • Department of Medicine, Monash University, Alfred Hospital, Melbourne, Victoria, Australia
    • Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Victoria, Australia

Received 9 February 2009; accepted 19 June 2009. published online 20 November 2009.

Abstract 

Objective

Malnutrition in cystic fibrosis (CF) is associated with poorer survival, but the determinants of fat-free mass (FFM) depletion are not well-characterized. It is unknown whether routine nutritional indicators, including body mass index (BMI), are adequate for detecting FFM depletion. This study aimed to determine the prevalence of FFM depletion in adults with CF, to compare fat-free mass index (FFMI) with BMI, and to identify predictors of FFM depletion.

Methods

This was a prospective cross-sectional study of 86 adults with CF (19–59 y old). Body composition was assessed using dual-energy X-ray absorptiometry to determine FFMI and BMI. FFMI percentiles and Z-scores were derived from a reference population of 156 healthy adults. FFM depletion was defined as an FFMI below the fifth percentile for age and gender and low BMI as <18.5kg/m2. Univariate and multivariate analyses identified predictors of FFMI and FFMI Z-score.

Results

Mean FFMIs were 18.3±1.9kg/m2 in men with CF and 15.8±1.1kg/m2 in women with CF (P<0.0005). FFM depletion was found in 14% of adults with CF, and low BMI was found in 18.6%. The sensitivity of BMI for detecting FFM depletion was 42%. Forced expiratory volume in 1 s as a percentage of predicted was independently associated with FFMI in women (r=0.62, P<0.0001) and men (r=0.28, P=0.045) and FFMI Z-score (r=0.41, P<0.0001).

Conclusion

FFM depletion was found in 14% of adults with CF, but was undetectable by BMI in 58% of these patients. These findings, together with the association of FFMI with forced expiratory volume in 1 s predicted, suggest a role for body composition assessment in adult CF care.

Keywords: Cystic fibrosis, Malnutrition, Fat-free mass, Nutritional assessment, Body composition, Dual-energy X-ray absorptiometry

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 This study was partly funded by the Australian Cystic Fibrosis Research Trust. S. J. K. was the recipient of a National Health and Medical Research Council of Australia Postgraduate Scholarship and a Cystic Fibrosis Victoria Research Award.

PII: S0899-9007(09)00307-4

doi:10.1016/j.nut.2009.06.026

Nutrition
Volume 26, Issue 7 , Pages 753-759, July 2010

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