Adherence to Plant-Based Diets and Risk of CKD Progression and All-Cause Mortality: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

Abstract

Rationale & objective: Studies have shown that generally healthy individuals who consume diets rich in plant foods have a lower risk of incident chronic kidney disease (CKD) and cardiovascular disease. This study investigated the prospective associations of plant-based diets with the risk of CKD progression and all-cause mortality in individuals with CKD.

Study design: Prospective cohort study.

Setting & participants: 2,539 participants with CKD recruited between 2003-2008 into the Chronic Renal Insufficiency Cohort (CRIC) Study.

Exposure: Responses on the Diet History Questionnaire were used to calculate scores for the overall plant-based diet index, healthy plant-based diet index, and unhealthy plant-based diet index.

Outcome: (1) CKD progression defined as≥50% estimated glomerular filtration rate decline from baseline or kidney replacement therapy (dialysis, transplant) and (2) all-cause mortality.

Analytical approach: Cox proportional hazards models to compute hazard ratios and 95% confidence intervals adjusting for lifestyle, socioeconomic, and clinical covariates.

Results: There were 977 CKD progression events and 836 deaths during a median follow-up period of 7 and 12 years, respectively. Participants with the highest versus lowest adherence to overall plant-based diets and healthy plant-based diets had 26% (HR, 0.74 [95% CI, 0.62-0.88], P trend<0.001) and 21% (HR, 0.79 [95% CI, 0.66-0.95], P trend=0.03) lower risks of all-cause mortality, respectively. Each 10-point higher score of unhealthy plant-based diets was modestly associated with a higher risk of CKD progression (HR, 1.14 [95% CI, 1.03-1.25) and all-cause mortality (HR, 1.11 [95% CI, 1.00-1.23).

Limitations: Self-reported diet may be subject to measurement error.

Conclusions: Adherence to an overall plant-based diet and a healthy plant-based diet is associated with a reduced risk of all-cause mortality among individuals with CKD. An unhealthy plant-based was associated with an elevated risk of CKD progression and all-cause mortality.

Plain-language summary: Plant-based diets are healthful dietary patterns that have been linked to a lower risk of chronic diseases. However, the impact of plant-based diets on clinical outcomes in patients with chronic kidney disease (CKD) is not well established. In 2,539 individuals with CKD, we examined the associations of adherence to 3 different types of plant-based diets with the risks of CKD progression and all-cause mortality. We found that following an overall plant-based diet and a healthy plant-based diet was associated with a lower risk of all-cause mortality. By contrast, following an unhealthy plant-based diet was associated with a higher risk of CKD progression and all-cause mortality. These results suggest that the quality of plant-based diets may be important for CKD management.

Keywords: Chronic kidney disease; death; dietary intake; end-stage renal disease; morbidity/mortality; plant-based diet; plant-based protein.

Figure 1.

Adjusted hazard ratios and 95% CIs for all-cause mortality, according to the continuous overall plant-based diet index. The histogram shows the distribution of scores for the plant-based diet index in gray. The solid line represents the adjusted hazard ratio (log scale) for the association between overall plant-based diet index and all-cause mortality, modeled using linear spline terms with 1 knot at the 10th percentile of the overall plant-based diet index (score, 43), which was used as the reference point. The dashed lines represent the 95% confidence interval (log scale). Hazard ratios were adjusted for clinical site, age, sex, race, education, income, total energy intake, physical activity, smoking status, alcohol use, obesity status (categorical variable with cut off at 30 kg/m2), kidney function (eGFR), 24-hour urinary protein, diabetes, hypertension, history of cardiovascular disease, and use of ACE inhibitors or ARBs.