Relationship between DII score with anthropometric indices and PSQI score
The Association between DII score with anthropometric variables including weight, BMI, WC, HC, AVI, BAI, and conicity index and PSQI score is illustrated in Table 3. According to continuous DII, in the unadjusted model, there was a significant negative association between DII score with weight, BMI, WC, HC, AVI, BAI, and conicity index (p for all < 0.05); however, in Model 1 and after adjustment for energy intake this negative correlation disappeared and a positive correlation was found, but it was not statistically significant for all anthropometric variables (p ≥ 0.05) (Table 3).
Regarding the Association between DII score (continuous DII) as an independent variable and PSQI continuous score as dependent variables, in the unadjusted model, there was no significant association between these two variables (β-Coefficients = 0.18 and p = 0.1). While, in adjusted models, there was a significant positive association between DII and sleep score (model 1: β-Coefficients = 0.29 and p = 0.02, model 2: β-Coefficients = 0.30 and p = 0.02). Also, according to quartiles of the DII, there was a significant positive association between DII and sleep score in all 3 models, unadjusted, model 1, and model 2 (unadjusted: β-Coefficients = 0.41 and p = 0.04, model 1: β-Coefficients = 0.61 and p = 0.008, and model 2: β-Coefficients = 0.60 and p = 0.01, respectively ) (Table 3).
Odds ratios (95%CI) for obesity and sleep quality, according to quartiles of DII, are presented in Table 4. There was a significant difference in the odds ratios between the quartile 1 (the reference quartile) (unadjusted model: OR= 0.33 (CI: 0.14-0.74), P for trend =0.002; model 1: OR= 0.31(CI: 0.12-0.78), P for trend = 0.005; model 2:OR=0.30 (CI:0.12-0.78), P for trend = 0.005) to quartile 4(unadjusted model: OR= 1.13(CI: 0.45-2.80); model 1: OR= 1.11(CI: 0.44-2.79); model 2:OR=1.13(CI:0.44-2.87), P for trend = 0.005). Also, odds ratios increased significantly from quartile 2 to quartile 4 in all models for DII and sleep quality.
On the other hand, according to the continuous score of DII, there was a significant positive association between DII and sleep quality in all 3 models: unadjusted, model 1, and model 2 (OR= 1.21 (CI: 1.05-1.40), OR= 1.21 (CI: 1.03-1.43), and OR= 1.22 (CI: 1.03-1.44), respectively(Table 4).