So next, we'll discuss some of the work that our group has done looking at dietary patterns and kidney disease. So you'll recall that we were working from this model that displays the potential barriers to healthful eating that socially disadvantaged groups might face. Here in this figure, I'm sharing that model again, which begins with trouble with limited availability of healthy food which can lead to poor dietary patterns. So we wanted to focus a bit on the relationship between poor dietary patterns and risk of new cases or incident chronic kidney disease as well as chronic kidney disease progression. So we focused our attention on limited fruits and vegetables in the diet. So around the time that we were doing this work, there were a number of studies that came out looking at dietary acid load as a potential risk factor for a number of different health conditions. So in our diets, for those of us who follow dietary patterns that are rich in meats and other animal proteins, those are considered dietary patterns that lead to a lot of production of acid in our bodies, which then ultimately leads to a greater amount of acid that the kidneys must handle. Whereas for people whose dietary patterns are more rich in plant-based foods, they have a more base-producing dietary pattern, again, presenting more base to the kidneys. So foods that are going to be rich in acid include food such as hard and process cheeses, whereas foods that are more base-producing include foods such as raisins. I was very excited to see that wine and coffee are on the base-producing in the spectrum as well. So we were interested in whether dietary acid load actually might have a relationship with chronic kidney disease disparities in the United States. So what we did was to conduct a study in the context of the National Health and Nutrition Examination Survey using data again from in NHANES. What I'm sharing in this figure is the range of net acid excretion that we observed across the population in this NHANES sample. Here, on the y-axis, we're looking at the prevalence of chronic kidney disease in adults across the different stages of chronic kidney disease. I'll note that we were looking at stages one through four of chronic kidney disease, with four being the most severe stage of chronic kidney disease. So the colors in the bars represent those different stages of chronic kidney disease. What we found in this study was that the prevalence of chronic kidney disease was greatest among people who were in quantile 5 for net acid excretion. This reflected the amount of dietary acid load that they were experiencing as a result of their particular dietary pattern. So in that same study, we also found that poverty and non-Hispanic black race were both associated with higher dietary acid load. So then we thought, "There is a dietary pattern that we are aware of that's quite popular, and that's called the Dietary Approaches to Stop Hypertension Diet or the DASH diet." It is a dietary pattern, as it turns out, that is low in dietary acid load. So this dietary pattern, as some of you may be familiar, when people do follow it, has been found to help to lower blood pressure and also to protect individuals from cardiovascular disease, as well as other chronic diseases. So we wanted to look at the relationship between the DASH diet and kidney disease. So in this figure, I'm just reminding those of you who may be less familiar with the DASH diet of its components. So it is a dietary pattern that is rich in fruits and vegetables with also rich sources of whole grains. It includes moderate amounts of meats, and fish, and other alternatives to meat. It has a modest amount of low-fat dairy foods included in the pattern, and it is a dietary pattern that is comprised of limited amounts of fats and sugars. So in the context of a research study, also in clinical care as it turns out, an individual's DASH score can be calculated. So this is a score that has nine points as a total possible score, and it's based upon three macronutrients and six micronutrients. Micro nutrients. So if an individual hits a target for any of these nutrients, then they're given a score of one point and there are some intermediate targets that are worth a half of a point. If a person has a total DASH score of 4.5 or greater then they're considered to be adherent to a DASH like dietary pattern. So we made use of that DASH score to then look at how closely individuals living either in poverty or not living in poverty were following a DASH like diet. So in this table I'm sharing with you some data from the HANDL Study, which is the Healthy Aging in Neighborhoods of Diversity Across the Lifespan study. Wherein we looked at the nine nutrients from the DASH dietary pattern that I mentioned in the previous slide, and we look to see whether there were any differences in the achievement of these DASH targets across the poverty group and then versus the non-poverty group. We did find some notable differences in that those who were living in poverty consumed more cholesterol and lesser amounts though of fiber, magnesium, calcium, and potassium than those who were not living in poverty. Interestingly, there was no difference in the amount of sodium that was consumed by the two groups and this is thought to be due to the fact that most of us are consuming too much sodium in these values importantly, a values per 100 kilocalories a day of dietary intake. So when we looked overall at the total DASH score for both of the groups, we found that overall the scores were quite low, reminder again that adherence would be at a score of 4.5 or greater, but we did find that the poverty group had a lower DASH score than the non-poverty group and a very, very low proportion of either group were actually adherent to a DASH like dietary pattern. So we went on to see how the DASH dietary pattern related to prevalence of chronic kidney disease and so in this case we were looking at the prevalence of a glomerular filtration rate of less than 60 milliliters per minute, which is a measure of kidney function. So we did continue to stratify the population that we were looking at by the poverty group versus the non-poverty group. So in this figure, I'm sharing with you what we found when we compared the poverty versus the non-poverty groups, with the poverty group represented by the striped bars and the non-poverty group represented in the solid colored bar. What we found is this gradient, if you will, wherein the prevalence of chronic kidney disease noted on the y-axis appeared to be greatest at the lowest level of DASH diet adherence among the poverty group, compared particularly to those who are at the highest level of DASH dietary adherence, again, among the poverty group, but we did not find this gradient among those who were not living in poverty. In fact, when we went on to do further adjustment in our analyses for some of the known confounders or some of the expected confounders in the association between dietary pattern in risk of kidney disease. We continue to find this statistically significant association between level of adherence to a DASH like diet and risk of prevalent chronic kidney disease among people living in poverty that we didn't see in those who did not live in poverty. So we were left thinking, "Well, perhaps if a person who does live in poverty is somehow able to follow a more healthful diet, then perhaps they may receive a little bit more benefit from that than a person, for example, who doesn't live in poverty and may not face some of the same barriers to their overall health may find if they were to follow a healthful diet." So it was a curious finding for our group. Then we went on to think about how these poor dietary patterns might lead to chronic kidney disease through their influence on other chronic kidney disease risk factors. For this piece of our work, we conducted a qualitative research study. I mean, here what we were aiming to do was to try to complement some of the findings that we had in our epidemiologic studies. So we recruited participants for a focus group study and the individuals that were eligible to be included had to have a family history of a first-degree relative having end-stage renal disease, which is also referred to as kidney failure, they had to have a biological risk factor for kidney disease and these could either be diabetes, hypertension, cardiovascular disease, HIV, or obesity. Then finally, they also had to have some indicator of low socioeconomic status. We included that last criteria because we particularly wanted to understand the perspectives of individuals who may face barriers to healthful eating. So in this study, when we examined the perceived barriers to chronic kidney disease prevention through dietary changes, the participants in our focus groups pointed out that healthy foods are expensive and unavailable in certain neighborhoods. One participant offered this quote that I'll share with you. They said, "And what we have in our neighborhoods, and most low-income neighborhoods, is fast food restaurants everywhere. You hardly see a farmers' market or fresh produce stand, or even fresh produce in the supermarket. As soon as you walk in the market, the first thing you see is cakes, cookies, chips, cereal with loads of sugar." So they pointed out this issue of unavailability of healthy foods. The participants also pointed out a number of other barriers, including family members' dietary requirements and their preferences being an issue in terms of considering changing their habits. They mentioned things such as the grandparent living at the household had specific requirements due to their health conditions or the children had preferences that many children have that it would be difficult for them to change their dietary habits. They also pointed out that unhealthy foods are more convenient to prepare or to access than are healthy foods, and pointed out things such as issues with storing fresh produce, and the shelf life of those foods. Then finally, they pointed out that unhealthy dietary patterns have been a lifelong habit for them, and therefore, difficult to break. When we went on in our qualitative research study to ask the participants about interventions that they may find acceptable, if we were interested in helping people such as them who are at high risk for chronic kidney disease, we focused on dietary interventions, and some of the things that the participants pointed out is that they would be open to having a doctor or a nutritionist teach them about the DASH diet. They would also be open to education that might be delivered either via social media or text messaging, or they would be interested in group seminars and other modes of getting the information to them. They were very interested in fruit or vegetable vouchers that could be provided to people like them, and also found the idea of pre-made meals that might be delivered to them to help them change their dietary patterns to be something that might be attractive. Then finally, they gave a lot of attention to the idea of a family or household-based intervention, given that they felt that in order for them to make a dietary change, their entire household would likely need to buy in to that change. So based on the findings from our focus group study, we then conducted a procedure or a method called intervention mapping. This is a method of integrating theory and empirical findings from the literature, as well as data collection from the target population in order to move forward with developing an intervention. So it follows six steps, which we followed in our process of then going on and developing an intervention. With the first step being a needs assessment, which we considered that to be conducted in the context of our focus group study, as well as some of the epidemiologic studies that we had conducted. The second step involves definition of objectives and specification of the changes needed. Here we defined what our primary goal would be around reducing progression of chronic kidney disease, the next step involves theory-based methods and practical strategies, and so in our case, we wanted our intervention, which would focus on dietary change to be rooted in a methodology around behavioral change that might be effective in this population. The fourth step involves intervention design itself, the fifth step involves adoption and implementation of the intervention, and then finally, an evaluation plan is important for how the actual intervention will be evaluated once completed. So we knew in our case that the desired intervention features would include a target population of low socioeconomic status African-Americans, we wanted them to have clinical risk factors for progression of chronic kidney disease. We wanted them to reside in food deserts because we presumed that those individuals might have the greatest need for the type of intervention that we were interested in conducting. We were very focused on our desire to have our intervention lead to dietary modification, with a particular focus on an increase in fruit and vegetable intake, as well as a reduction in dietary acid load. We also wanted to help the individuals who would be a part of our intervention to be able to reduce their sodium intake, given some of the literature around the importance of reducing sodium for improving outcomes related to kidney diseases as well as hypertension, which is a risk factor for chronic kidney disease progression. The desired clinical outcomes for our study were to reduce a marker of kidney disease. In our case, we wanted to focus on protein in the urine or albuminuria, and we also wanted to improve blood pressure. Then our desired future outcomes for our study was to have it lead to sustainable behavior change and for it to be a scalable program, we didn't want to just conduct our study in this research setting and have it not be something that could be scaled up to potentially be even a public health program. Then finally, we did want ultimately to be able to have a public health impact. So after conducting the intervention mapping and considering these desired features of our intervention, we moved forward and were able to receive funding from the National Institutes of Health for what we call the Five, Plus Nuts and Beans for Kidneys Trial. This intervention study is based upon a successful pilot study called the Five Plus Nuts and Beans Study that was led by doctors Pete Miller and Dr. Jessica Yea. This new study that's focused on people with kidney disease is a 12 month community-based dietary randomized control trial that includes 150 African-American participants with hypertension plus proteinuria or albuminuria as measured here. Our hypothesis is that delivery of nutritional advice to adopt a DASH-like diet plus $30 a week worth of potassium rich foods, which are going to be primarily fruits and vegetables, as well as nuts and beans. That providing these types of foods tailored to the personal choices of the participants in our study and tailored to the availability in neighborhood's stores will ultimately lead to a reduction in urinary albumin excretion. In order to conduct this study, we have partnered with a number of community partners, including ShopRite grocery store, whose logo is featured in the middle of the slide that I'm sharing with you. We've also worked with a highly engaged community advisory board that has an interest in kidney disease, and our community advisory board does include some patients who are currently treated with chronic kidney disease. So we engaged these stakeholders both in the design of our intervention and including having several members of our community advisory board actually named in our grant application, and the advisory board members are also engaged with us along in the conduct of the actual intervention. To close our lecture, I think there are a few take-home points that are important. We've highlighted that social epidemiology research methods can be used to inform a new health equity interventions. We've also highlighted that targeted interventions show promise in addressing gaps in health equity. We provided for you an illustration of how collaborations among patients, researchers, providers, policymakers, and other stakeholders are critical to achieve health equity. On the right-hand side of your slide, we highlight a quote from Fannie Lou Hamer, who was a civil rights activist quite famous for saying, ''I'm sick and tired of being sick and tired''. We feel that this message from Fannie Lou Hamer really does help us to focus on how disadvantaged populations really do need the support of public health researchers and others engaged in this type of work in order to help us to achieve health equity. Thank you.
