Associations between dietary index for gut microbiota with COPD prevalence and all-cause mortality: insights from the 1999–2018 NHANES data

Gut microbiota dysbiosis plays a vital role the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to: (1) examine the cross-sectional association between dietary index for gut microbiota (DI-GM), a novel biomarker reflecting gut microbiota composition and function, and COPD prevalence; and (2) assess the prognostic significance of DI-GM score for all-cause mortality in COPD patients. We analyzed data from the 1999–2018 National Health and Nutrition Examination Survey. DI-GM score was calculated from 24-hour dietary recall. Primary outcomes were COPD prevalence and all-cause mortality risk in COPD patients. Multivariable logistic regression assessed the association between DI-GM and COPD prevalence, while Cox proportional hazards models evaluated all-cause mortality risk in COPD patients. The prevalence of COPD was 6.87% among the 22,859 participants included. Compared to participants with DI-GM score of 0–3, the odds ratio (95% confidence interval) for DI-GM score of 4, 5, and ≥ 6 were 0.88 (0.70–1.11), 0.78 (0.64–0.97), and 0.75 (0.62–0.90), respectively. During a median follow-up time of 84 months, a total of 570 (28.15%) participants died among the 1,580 COPD participants. Compared to DI-GM score of 0–3, the hazard ratios (95% confidence intervals) for DI-GM score of 4, 5, and ≥ 6 were 0.78 (0.60–1.01), 0.63 (0.47–0.83), and 0.69 (0.56–0.85), respectively. Higher DI-GM scores are significantly associated with both reduced COPD prevalence and improved survival in COPD patients. Our results suggest dietary modifications targeting gut microbiota may represent a novel strategy for COPD prevention and management.