Association of chronic kidney disease with dietary inflammatory index in adults aged 50 years and older: dose-response analysis of a nationally representative population-based study

Objective Dietary inflammatory index (DII) is associated with systemic inflammatory markers, which have been linked to the development of chronic kidney disease (CKD). However, epidemiological studies on the association of DII scores with CKD are sparse. This study aimed to quantitatively assess the dose-response relationship of DII scores with the prevalence of CKD. Methods Adults (≥50 years) from the 2007–2018 National Health and Nutrition Examination Survey (N=12,090) were included. DII scores were calculated based on 27 nutritional parameters. The outcome of interest is the prevalence of CKD 3-5 stages, which is defined as estimated glomerular filtration rate <60 mL/min/1.73 m2. The non-linear dose-response relationship of DII scores with the prevalence of CKD stages 3–5 was assessed with restricted cubic splines. Stratified analyses were conducted by age, sex and race/ethnicity. Covariates included age, sex, body mass index, race/ethnicity, educational, ratio of family income to poverty, smoking, physical activity, hypertension, diabetes, and daily intakes of total plain water, sodium and energy. Results The weighted prevalence of CKD stages 3–5 was 14.77%. The relationship of DII scores with CKD stages 3–5 was linear, and the odds ratios (95% confidence intervals) of CKD stages 3–5 were 0.68 (0.51-0.84) for -2 (DII score), 0.83 (0.74-0.93) for -1, 1.00 for 0 (reference value), 1.20 (1.07-1.32) for 1, 1.41 (1.16-1.66) for 2, 1.63 (1.28-1.98) for 3, 1.84 (1.34-2.34) for 4, and 2.08 (1.30-2.86) for 5. The linear relationship pattern of DII scores with CKD stages 3–5 was observed in stratified analyses by age, sex and race/ethnicity, respectively. Conclusions Higher DII scores were independently and linearly associated with the odds of CKD stages 3–5, which deserves to be confirmed in further prospective cohort studies.