Abstract
BACKGROUND AND OBJECTIVE: Weight loss and reduced fat-free mass are independent risk factors for mortality among patients with chronic obstructive pulmonary disease (COPD). These factors are important for determining diet therapy and examining the validity of assessment for energy intake (EI). We assessed the agreement of EI between a brief-type self-administered diet history questionnaire (BDHQ) and the doubly labelled water (DLW) method among male patients with stable/at risk for COPD. METHOD: In this cross-sectional observational study, data for 33 male patients were analysed. At the first visit, EI was estimated using a BDHQ (EI(BDHQ)). Total energy expenditure (TEE) was measured during 13-15 days by the DLW method, while corrected EI was calculated using the TEE and weight change during the DLW period (EI(DLW)). The difference between EI(BDHQ) and EI(DLW) was evaluated by the Bland-Altman method. Multiple regression analysis was used to determine the proportion of variance in the difference between EI(BDHQ) and EI(DLW), as determined by the patient's characteristics. RESULTS: EI(BDHQ) was 2100 (95% CI: 1905 to 2295) kcal/day in the total population. A fixed bias was observed between EI(BDHQ) and EI(DLW) as -186 (95% CI: -422 to 50) kcal/day, while a proportional bias was not detected by the Bland-Altman analysis. Age, weight, anxiety and interleukin 6 were responsible for 61.7% of the variance in the difference between both EIs in a multiple regression model. CONCLUSIONS: The BDHQ underestimated EI among male patients with stable/at risk for COPD, but this estimation error was within an acceptable range compared with previous studies. EI(BDHQ) precision might be improved by considering common COPD traits, including inflammatory condition and mental state.