[Assessment of nutritional status and body composition in patients with COPD: comparison of several methods]

In chronic obstructive pulmonary disease (COPD), loss of fat-free mass (FFM) reduces the prognosis.

To assess their nutritional status and compare the relevance of several nutritional criteria, 47 COPD patients, already enrolled in our pulmonary rehabilitation programme, were evaluated. Assessment of nutritional status included anthropometry, serum albumin and transthyretin, bioimpedance analysis (BIA) and 3-day dietary record. The accuracy of these nutritional parameters was determined by comparison with FFM measured by BIA. The agreement between BIA and the 4-skinfold-thickness method was determined by statistical correlation and the Bland and Altman method. Energy intake, health care requirements and quality of life (QOL) score were compared with the FFM.

According to the criteria used, the prevalence of undernutrition varied between 4 and 49%. In comparison with BIA, body mass index (BMI) below 20, triceps skinfold below the 5th percentile and transthyretin below 0.20 g/L had a specificity of around 100% for the diagnosis of undernutrition. There was a good agreement between BIA and the 4-skinfold-thickness method for the assessment of FFM (r=0.86, P<0.0001). Prior to any nutritional intervention, the patients with low FFM had higher protein-energy intake than patients with normal FFM. Low FFM was associated with a greater number of visits to the doctor, but had no impact on QOL.

The assessment of FFM by BIA is the most sensitive method to detect undernutrition in COPD patients. Lowered values of BMI, triceps skinfold and transthyretin are predictive of loss of FFM.