Dietary Behaviors and Social Determinants of Health Among Adults Living with Sickle Cell Disease

Background: Social determinants of health (SDoH) may impact outcomes in sickle cell disease (SCD), and recent literature reports that particular SDoH, such as food insecurity and housing insecurity, may impact diet choices for individuals with SCD. Notably, health outcomes in SCD are linked to diet choices through increased protein and caloric needs, and through nutrients, such as polyphenols, omega fatty acids and micronutrients, which are involved in SCD pathophysiology. The connection between SDoH and diet quality may occur through multiple pathways including access to food, affordability, chronic pain and psychosocial factors at the individual and family level. Importantly, the impact of this connection may relate to outcomes such as pain frequency, hospitalizations, and SCD pathophysiologic biomarkers, such as inflammation.

Study Design and Methods: The Diet and SCD Study (NCT: 05170412) is an observational mixed-methods study initiated in 2021 at the National Institutes of Health Clinical Center (NIH CC) in Bethesda MD with a target sample of 75 adults living with SCD in the United States. The purpose of the study is to evaluate associations between SDoH (food insecurity, neighborhood food access, education, employment, healthcare access), dietary intake, and population health related outcomes among adults living with SCD. Study inclusion criteria consists of adults (≥18 years of age) residing within the United States at the time of screening who have a confirmed diagnosis of sickle cell disease with any genotype, and are not hospitalized at the time of enrollment.

To ensure participation from adults in diverse regions of the United States, the study has a hybrid design of in-person and telehealth procedures. In-person protocol visits are conducted at the NIH CC. The CC clinical visit includes a clinical assessment, anthropometric measurements, phlebotomy, as well as monitored/proctored electronic surveys that collect SDoH and disease severity variables. The telehealth protocol visit includes a virtual clinical assessment, phlebotomy at a local laboratory center, as well as the same monitored/proctored electronic surveys completed by CC clinical visit participants. A dietary behavior semi-structured interview is conducted at both the CC clinical visit and telehealth protocol visit to garner participants' personal stories related to food choices and diet. Laboratory variables include SCD disease specific markers, amino acid levels, and measurement of inflammatory cytokine markers. All participants undergo two unannounced phone-administered 24-hour dietary recall interviews with trained NIH nutrition staff to measure recent dietary intake. Data from 24-hour recall interviews are used to determine fluid, caloric, macro and micronutrient, and polyphenol intake. Usual dietary intake of foods of potentially related to SCD pathophysiology (cruciferous vegetables and thiocyanate-rich foods) is measured through self-administered electronic 12-month food frequency questionnaires. Primary objectives are to evaluate social determinants of health related to food security and access relevant to disease severity among adults living with sickle cell disease in the U.S. Secondary outcomes are to evaluate the association of dietary quality, specific dietary nutrient intake and serum levels, including amino acids and polyphenols, with disease severity. Tertiary outcomes include evaluating inflammatory and glucometabolic biomarkers with measures of social determinants of health. When completed, the Diet and SCD study will provide important information on the associations between SDoH, dietary quality, inflammatory biomarkers and disease severity for adults living with SCD and provide initial data for future cohort and intervention studies.