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Alternate Healthy Eating Index 2010 and risk of chronic obstructive pulmonary disease among US women and men: prospective study

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h286 (Published 03 February 2015) Cite this as: BMJ 2015;350:h286

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Re: Healthy diet and risk of COPD

We thank Young et al. for their interest in our recently published paper.

Regarding the first question raised by the authors about the magnitude of the association between AHEI-2010 score on risk of COPD, as compared with cohort studies of other chronic diseases, we reported a 33% lower risk for those higher (versus lower) AHEI-2010 scores. This is little bit stronger perhaps but generally consistent with previous studies looking at the association between AHEI-2010 and risk of developing chronic diseases (19%) [1], obesity (24%) [2], type 2 diabetes (13%) [3], epithelial ovarian cancer (15%) [4], and all-cause mortality (24%) [5]. The observed 33% reduction is of similar magnitude to the favorable association of higher AHEI-2010 score with healthy ageing and well-being (34%) [6].

Regarding the second question, even if we decided to investigate the individual role of each component score of the AHEI-2010, we believe that a healthy diet based on the overall AHEI-2010 is recommended to improve lung health, because all these individual items are strongly correlated. When we investigated the individual role of each component, we adjusted for the 10 others items to account for these correlations.
Regarding the third and final question raised by Young et al., we reported a non-significant negative association between whole grain intake and the risk of COPD (RR 0.82, 95%CI 0.48 to 1.38). We are less concerned about confounding by cured meat intake or smoking exposure. As stated in our publication, we faced a statistical power issue in the men (e.g., there were only 24 cases in the fifth quintile of whole grains intake). We hope that additional research on this topic will help to clarify these important issues.

References:
1. Chiuve SE, Fung TT, Rimm EB, Hu FB, Mccullough ML, Wang M, Stampfer MJ, Willett WC. Alternative dietary indices both strongly predict risk of chronic disease. J. Nutr. 2012; 142: 1009–1018.
2. Boggs DA, Rosenberg L, Rodríguez-Bernal CL, Palmer JR. Long-term diet quality is associated with lower obesity risk in young African American women with normal BMI at baseline. J. Nutr. 2013; 143: 1636–1641.
3. Jacobs S, Harmon BE, Boushey CJ, Morimoto Y, Wilkens LR, Le Marchand L, Kröger J, Schulze MB, Kolonel LN, Maskarinec G. A priori-defined diet quality indexes and risk of type 2 diabetes: the Multiethnic Cohort. Diabetologia 2015; 58: 98–112.
4. Xie J, Poole EM, Terry KL, Fung TT, Rosner BA, Willett WC, Tworoger SS. A prospective cohort study of dietary indices and incidence of epithelial ovarian cancer. J. Ovarian Res. 2014; 7: 112.
5. Reedy J, Krebs-Smith SM, Miller PE, Liese AD, Kahle LL, Park Y, Subar AF. Higher diet quality is associated with decreased risk of all-cause, cardiovascular disease, and cancer mortality among older adults. J. Nutr. 2014; .
6. Samieri C, Sun Q, Townsend MK, Chiuve SE, Okereke OI, Willett WC, Stampfer M, Grodstein F. The association between dietary patterns at midlife and health in aging: an observational study. Ann. Intern. Med. 2013; 159: 584–591.

Competing interests: No competing interests

20 February 2015
Raphaëlle Varraso
Epidemiologist
Carlos A Camargo
INSERM U1168
16 avenue Paul Vaillant Couturier 94807 Villejuif, France