The efficacy of dietetic intervention in patients with chronic obstructive pulmonary disease
Authors: Bottle L. , Engel B. , Hart K. , Klopper T. 
Published: July 2008

Background:  Clinical trials have shown that pulmonary rehabilitation can improve the functional status and quality of life of chronic obstructive pulmonary disease (COPD) patients (Lacasse, 2006) but there is no research examining the efficacy of group dietetic intervention during standard 8 week rehabilitation courses. Current input is usually limited to a 1 h nutrition education session. This pilot study aimed to investigate whether patients receiving additional dietetic intervention during pulmonary rehabilitation significantly increased their general nutritional knowledge, thereby facilitating improvements in dietary intake and nutritional status.

Methods:  Patients were recruited from two courses of pulmonary rehabilitation and randomly allocated to a control group or an intervention group. Anthropometry (height, weight, body mass index, mid arm circumference and triceps skinfold), 3 day food diaries and nutritional knowledge questionnaires covered guidelines, food groups, choosing healthy options and diet and COPD were completed at baseline and at the end of 8 weeks. In week 2 both groups received the same nutrition education session which covered healthy eating during periods of stability as well as advice on coping with loss of appetite and reduced intake during illness and exacerbations. The intervention group was followed up during weeks 4, 6 and 7 when further anthropometric measurements were taken and additional dietary advice was provided, which addressed issues raised by individual patients. Information from food diaries was converted to nutrients using Windiets dietary analysis software. Statistical analyses were carried out using SPSS (v14) and included Mann–Whitney U non parametric tests, paired t‐tests and Spearman correlations used for comparisons over time and between groups. For analysis purposes patients were classified as normal weight (NW) and overweight (OW). Approval was obtained from the appropriate Ethics Committee.

Results:  Changes reported were not statistically significant (P > 0.05). Complete data sets were obtained for six control (NW = 2, OW = 4) and five intervention (NW = 1, OW = 4) patients. Nutritional knowledge increased in the control group by 5% compared to 3% in the intervention group. Control NW patients increased their energy intake resulting in a mean weight gain of 0.5 kg (SD 3.3). OW control group patients increased their energy intake by 12.4% (16.9) with a mean weight gain of 0.2 kg (2.5). All control patients increased their intake of in total fat, saturated fatty acids (SFA), sugars and sodium. Conversely there was a decrease in energy intake in the intervention group of 14.4% (17.8) and a mean weight loss of 1.5 kg (1.2) (three out of four overweight patients lost weight). Improvements in diet were shown with reduced intakes of total fat, SFA, sugars and sodium. The NW patient in the intervention group regained weight that had previously been lost. These changes did not correlate with changes in nutritional knowledge.

Discussion:  An increase in nutritional knowledge was expected to facilitate appropriate changes in dietary intake and nutritional status. Despite the lack of correlation between dietary knowledge and intake, beneficial outcomes were none‐the‐less observed in the intervention group. The trend for weight gain in OW control group patients, and weight loss in OW intervention group patients contrasted with results seen by Slinde et al. (2002) where the control OW patients lost weight, and OW intervention patients gained weight. It is possible that in the current study, patients in the intervention group were motivated to lose weight with repeated exposure to the dietitian, rather than an increase in nutritional knowledge. Significant anthropometrical changes were unlikely to be observed in 8 weeks, and further follow up may be necessary to establish sufficient evidence for the most efficacious level of dietetic intervention. The small sample sizes, especially with regard to weight sub groups, limits the conclusions which can be drawn. Further research is recommended, using a larger sample size, in order to make recommendations for dietetic best practice.

Conclusion:  The results of this study did not show statistical significance and the association between nutritional knowledge and improved nutritional outcomes remains unclear. However, the findings may have clinical significance since they appear to show that additional dietetic intervention may benefit the nutritional status of patients with COPD attending pulmonary rehabilitation.

References  Lacasse, Y., Goldstein, R., et al. (2006) Pulmonary rehabilitation for chronic obstructive pulmonary disease. Cochrane Database Syst. Rev. 4, CD003793.

Slinde, F., Gronberg, A.M., et al. (2002) Individual dietary intervention in patients with COPD during multidisciplinary rehabilitation. Respir. Med. 96, 330–336.