Development and External Validation of the Cantonese Dietary Index: A Population-Based Approach to Assess Diet...

Objectives: We aimed to develop a practical dietary quality score reflecting the Cantonese dietary pattern and evaluate its validity against established indices. Methods: The Cantonese Dietary Index (CDI, ) was constructed based on Cantonese dietary principles. Reliability was assessed using intraclass correlation coefficients (ICC) over 5-6 years in the GNHS. Validity was evaluated using Spearman correlations with dietary indices (aMed, DASH, and DBI) and by comparing associations with metabolic syndrome (MetS) across dietary indices using regression models. The CDI was developed from the Guangzhou Nutrition and Health Study cohort (GNHS) and validated in the Tianjin Chronic Low-grade Systemic Inflammation and Health (TCLSIH) cohort and the National Health and Nutrition Examination Survey (NHANES). Results: A total of 4025 (GNHS), 29,165 (TCLSIH), and 28,890 (NHANES) participants were included. Median CDI scores were 58.5, 51.0, and 49.0, respectively. The 5-6-year ICC was 0.33 (p < 0.001). The CDI was moderately correlated with dietary indices across the three studies (GNHS: from -0.55 [DBI-LBS] to 0.61 [DASH], TCLSIH: from -0.61 [DBI-DQD] to 0.71 [DASH], NHANES: from -0.33 [DBI-DQD] to 0.68 [DASH]). The odds ratios (95% CIs) of MetS for CDI, aMed, and DASH scores were 0.80 (0.74, 0.86), 0.91 (0.84,0.99), and 0.83 (0.77, 0.90) in GNHS, 0.95 (0.92, 0.98), 0.99 (0.96, 1.02), and 0.92 (0.89, 0.95) in TCLSIH, and 0.80 (0.77, 0.84), 0.80 (0.76, 0.84), and 0.72 (0.69, 0.76) in NHANES. Conclusions: The CDI demonstrated moderate validity and reliability in Chinese populations and was inversely associated with MetS.