the relationship between different diet quality indices and severity of airflow obstruction among copd patients

background: chronic obstructive pulmonary disease (copd) is a major public health problem worldwide. smoking is the number one cause of copd; however, genetic, environmental and dietary factors contribute to the etiology of this disease. in this study, we assessed the association between three diet quality indices -the healthy eating index-2005 (hei-2005), the healthy eating index-2010 (hei-2010), and mediterranean diet score (med)- and the severity of disease in copd patients.   methods: this cross-sectional study was performed at  rasul-e-akram hospital in tehran on 121 copd patients with the mean age of (sd) of 66.1(10.9) years. a pulmonary specialist diagnosed all participants based on a spirometry test. they were categorized into four groups (1, 2, 3, 4 stages of disease). three diet quality indices, spirometry test and determination of disease severity were performed for all the participants. ancova and kruskal-wallis test were used to assess the relationship between dietary quality indices and severity of the disease. the relationship between hei-2010, hei-2005, med score, their components and lung function was assessed using a multiple linear regression analysis. all analyses were done using spss 18.   results: reduction of the healthy eating index-2010 and med score were observed along with the increase in disease severity, but they were not significant. the relationship between the three diet quality indices and lung function showed a significant association between med score and forced expiratory volume in one second (fev1), the forced vital capacity (fvc) (β=2.9, 95% ci (1.1, 4.8), p=0.002), (β=2.8, 95% ci (0.9, 4.8), p=0.007), respectively.   conclusion: mediterranean dietary pattern and obtaining a better score on hei-2010 diet were associated with a better lung function test.