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The Association between the Global Diet Quality Score and All-Cause Mortality in Black South African Adults
Arole Shivambu1, Marlien Pieters2, Carina Mels3
1Centre of Excellence for Nutrition, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa.
Background:
Modifiable risk factors for cardiovascular diseases (CVDs) include diet quality. The Global Diet Quality Score (GDQS) was designed to provide a comprehensive diet quality assessment, yet very few studies have assessed its relationship with CVD and all-cause mortality, particularly in an African setting.
Objectives:
We aimed to determine the association between the baseline total GDQS, GDQS positive (GDQS+), and GDQS negative (GDQS-) and all-cause and CVD mortality after 13 y of follow-up in Black South African adults (aged 30-70 y). GDQS+ reflects healthy food intake, whereas GDQS- is reverse-scored (higher scores indicating lower intake of unhealthy foods). Across all GDQS measures, higher scores indicate better diet quality.
Methods:
The baseline dietary data from the Prospective Urban Rural Epidemiology-North West Province-South Africa study were used to calculate the GDQS, with mortality outcomes recorded 13 y later. Cox proportional hazards models were applied, stratified by sex, age group, and observation time tertiles. Models were adjusted for lifestyle factors and health status. Hazard ratios (HRs) were calculated for baseline GDQS tertiles.
Results:
The overall GDQS was low in both survivors and nonsurvivors, reflecting low intake of many GDQS healthy food groups, with only whole grains and liquid oils reaching desirable levels (to give maximum points to the GDQS+). Compared with tertile (T1), participants in T3 of the GDQS+ had a lower risk of all-cause mortality [HR: 0.69; 95% confidence interval (CI): 0.56, 0.86], whereas those in T3 of the GDQS- had a higher risk (HR: 1.39; 95% CI: 1.12, 1.73). No associations were found with CVD mortality.
Conclusions:
The GDQS is a valuable tool for investigating all-cause mortality risk in African populations through its GDQS+ submetric. However, caution is warranted when applying the GDQS in settings of dietary monotony or food insecurity, particularly the GDQS- submetric which gives maximum points for low intake/avoidance of unhealthy food groups.
