Food Insecurity Associated with Risk for Progression of CKD

The US Department of Agriculture defines food security as a person’s perceived ability to obtain nutritious and healthy food with essential nutrients, fruits, and vegetables, and limited amounts of saturated fats, sugar, and salt for an active and healthy life. Estimates of households in America classified as food insecure in 2014 were 14.3%; food insecurity was characterized as lack of the proper availability of or the means to obtain food, resulting in frequent hunger or inadequate intake of nutrients.

Lack of access to healthy foods contributes to poor diet composition and higher levels of diseases related to poor diets. There are associations between unhealthy dietary patterns and leading causes of chronic disease and death, including chronic kidney disease (CKD), coronary heart disease, diabetes, hypertension, and obesity. Unhealthy diets are also higher in dietary acid load due to lower consumption of fruits and vegetables, associated with progression of CKD.

Individuals with lower incomes are more likely to be food insecure than individuals with higher incomes. Tanushree Banerjee, PhD, and colleagues conducted a cross-sectional analysis of lower-income participants in the National Health and Nutrition Examination Survey (NHANES) 2003 to 2008, and the Healthy Aging in Neighborhoods of Diversity Across the Life Span (HANDLS) Study and found that food insecurity may play a role in disparities in kidney disease.

The researchers recently conducted a longitudinal cohort study designed to test the hypothesis that there would be an independent association between food insecurity and risk for progression to end-stage renal disease (ESRD) among persons with and without earlier stages of CKD. Results were reported in the American Journal of Kidney Diseases [2017;70(1):3847]. The study included 2320 adults ≥20 years of age with CKD and 10,448 adults without CKD enrolled in NHANES III (1988-1994) with household income ≤400% of the federal poverty level; the data were linked to the Medicare ESRD Registry for a median follow-up of 12 years.

Of the 2320 individuals with CKD in the NAHANES III study, 4.5% had food insecurity. Compared with food secure participants, those with food insecurity had lower incomes and were younger, less likely to be non-Hispanic black (28.8% vs 32.8%), and more likely to have diabetes (29.9% vs 25.0%), hypertension (73.9% vs 67.3%), and albuminuria (90.4% vs 77.1%; P<.05). Dietary acid load was greater for food insecure participants; however, the results were of borderline statistical significance.

Of the 10,448 participants without CKD, 5.7% had food insecurity. Compared with non-CKD participants who were food secure, those with food insecurity were more likely to have low educational attainment (67.0% vs 41.9%) and were younger, less likely to be non-Hispanic black (27.7% vs 28.8%), and less likely to have hypertension (31.5% vs 35.8%; P<.05).

Five point two percent (n=120) of NHANES III participants with earlier stages of CKD developed ESRD during a median of 12.4 years. In crude analyses, participants who reported food insecurity were 2.8 times more likely to progress to ESRD than those who were food secure. There was minimal change in the risk for progression to ESRD following multivariable adjustment for age, sex, and race/ethnicity relative hazard [RH], 2.64; 95% confidence interval [CI], 1.52-5.68. Adjustment for income further attenuated the results (RH, 2.15; 95% CI, 1.25-4.90). Further attenuation of the risk for ESRD occurred following adjustment for clinical risk factors of diabetes and hypertension (RH, 1.77; 95% CI, 1.19-4.20). After adjustment for estimated glomerular filtration rate and albuminuria, the RH was 1.39 (96% CI, 1.90-3.77); there was no material difference after adjustment for total caloric intake per day and body mass index (RH, 1.38; 95% CI, 1.08-3.10). Adjustment for dietary acid load resulted in RH of 1.22 (95% CI, 0.99-2.11).

In the group without CKD, 2.2% (n=226) of NAHNES III participants developed ESRD in a median of 14.4 years. Following adjustment for multiple variables, including demographics, poverty income ratio, clinical factors, kidney markers, and nutritional factors, there was no association between food insecurity and the risk for ESRD (RH, 0.77; 95% CI, 0.40-1.49).

Limitations to the study cited by the authors included the lack of laboratory follow-up data and measurements of food insecurity over time; defining food insecurity at a household level and determining ESRD on an individual level; lack of distinction between moderate and severe food insecurity; and using data from the early 1990s prior to implementation of changes in public assistance and food programs.

“In summary, we have observed that food insecurity in lower income individuals with earlier stages of CKD is associated with increased risk for ESRD and that this association is partially mediated by nutritional factors, including higher levels of dietary acid load. This finding may have important public health implications. Further studies might be considered to clarify whether the excess risk for ESRD apart from the traditional risk factors is confined to the nutritional factors that we measured or to other environmental factors. Better detection of food insecurity in a clinical setting and more systematic approaches to measuring food insecurity in people accessing the healthcare system for treatment of chronic diseases may be appropriate to determine the best ways to meet their needs and better their health outcomes. Dietary interventions to slow CKD progression that account for how the financial difficulties of participants might affect implementation of recommended dietary changes may be beneficial for low-income communities,” the researchers said.