Statistical Aspects of the Use of Biomarkers in Nutritional Epidemiology Research

Few strong and consistent associations have arisen from observational studies of dietary consumption in relation to chronic disease risk. Measurement error in self-reported dietary assessment may be obscuring many such associations. Attempts to correct for measurement error have mostly used a second self-report assessment in a subset of a study cohort to calibrate the self-report assessment used throughout the cohort, under the dubious assumption of uncorrelated measurement errors between the two assessments. The use, instead, of objective biomarkers of nutrient consumption to produce calibrated consumption estimates provides a promising approach to enhance study reliability. As summarized here, we have recently applied this nutrient biomarker approach to examine energy, protein, and percent of energy from protein, in relation to disease incidence in Women’s Health Initiative cohorts, and find strong associations that are not evident without biomarker calibration. A major bottleneck for the broader use of a biomarker-calibration approach is the rather few nutrients for which a suitable biomarker has been developed. Some methodologic approaches to the development of additional pertinent biomarkers, including the possible use of a respiratory quotient from indirect calorimetry for macronutrient biomarker development, and the potential of human feeding studies for the evaluation of a range of urine- and blood-based potential biomarkers, will briefly be described

Estimating The Costs And Cost-effectiveness Of Promoting Mammography Screening Among US-based Latinas

Purpose: We characterize the costs and cost-effectiveness of a community health worker (CHW)-based intervention to promote screening mammography among US-based non-adherent Latinas. Methods: The parent study was a randomized controlled trial for 536 Latinas aged 42-74 years old who had sought care within a safety net health center in Western Washington. Participants were block-randomized within clinic to the control arm (usual care) or intervention arm (CHW-led motivational interviewing intervention). We used the perspective of the organization implementing promotional activities to characterize costs and cost-effectiveness. Cost data were categorized as program set-up and maintenance (initial training, booster/annual training) program implementation (administrative activities, intervention delivery); and, overhead/miscellaneous expenses. Cost-effectiveness was calculated as the incremental cost of screening for each additional woman screened between the intervention and control arms. Results: The respective costs per participant for standard care and the intervention arm were $69.96 and$300.99. There were no study arm differences in 1-year QALYs among women who completed a 12-month follow-up survey (intervention= 0.8827, standard care = 0.8841). Most costs pertained to program implementation and administrative activities specifically. The incremental cost per additional woman screened was $2,595.32. Conclusions: Our findings are within the ranges of costs and cost-effectiveness for other CHW programs to promote screening mammography among underserved populations. Our strong study design and focus on non-adherent women provides important strengths to this body of work, especially give implementation and dissemination science efforts regarding CHW-based health promotion for health disparity populations

Can Community Gardens with Workshops Increase Gardening Behavior? A Navajo Wellness Collaboration

This paper seeks to evaluate the potential efficacy of a community gardening intervention on the Navajo Nation to increase gardening and healthy eating behaviors, which are potentially important in preventing obesity and related health conditions. Rates of obesity are high among American Indians, including those living on Navajo Nation land. Eating fresh fruits and vegetables is part of healthy eating. However, availability and access to fresh fruits and vegetables are severely limited on the Navajo Nation, due to distance and cost. One way to increase both availability and consumption of fresh fruits and vegetables is through community gardening, yet many on the Navajo Nation have limited knowledge and capacity to garden. Methods: We used a quasi-experimental pre-post study design to estimate the effect of a community gardening intervention. Primary outcomes of interest were gardening frequency and fruit and vegetable consumption. Community gardens were constructed and planted in two communities on the Navajo Nation. In addition, a series of gardening workshops were held in each community. Community members were recruited to complete surveys at time points before and after the workshops. The time between baseline and follow-up was approximately one year. Results: We surveyed 169 participants at one time point at least, across both communities, and 25 of these participated in the gardening workshops. Within the 169, there was a cohort of 32 participants completing both baseline and follow-up surveys. For this cohort, interest in gardening increased from 78% to 97% (p=0.014), but none of the changes in gardening self-efficacy, knowledge or gardening frequency reached statistical significance. There were no measurable changes in reported fruit and vegetable consumption, self-efficacy or knowledge. Overall, the reported financial barriers to gardening increased from baseline to follow-up from 4.6 to 5.5 (p=0.035). Altogether 52 participants completed follow-up. In this group, those who attended at least one workshop gardened more frequently at follow-up than those who did not attend any workshops (21 times per month compared to 10 times per month (p=0.07). Conclusion: Despite enthusiasm for the community garden in both the communities studied and the increased interest in gardening, workshop attendance and participant retention in the study were low. These factors limited our ability to evaluate the potential efficacy of the intervention on gardening and healthy eating behaviors. Nonetheless, we found some evidence that participating in gardening workshops may lead to increased gardening frequency. Future studies should augment the intervention to include explicit efforts to reduce barriers to long term engagement and extend intervention reach

Evaluation and Comparison of Food Records, Recalls, and Frequencies for Energy and Protein Assessment by Using Recovery Biomarkers

The food frequency questionnaire approach to dietary assessment is ubiquitous in nutritional epidemiology research. Food records and recalls provide approaches that may also be adaptable for use in large epidemiologic cohorts, if warranted by better measurement properties. The authors collected (2007–2009) a 4-day food record, three 24-hour dietary recalls, and a food frequency questionnaire from 450 postmenopausal women in the Women’s Health Initiative prospective cohort study (enrollment, 1994–1998), along with biomarkers of energy and protein consumption. Through comparison with biomarkers, the food record is shown to provide a stronger estimate of energy and protein than does the food frequency questionnaire, with 24-hour recalls mostly intermediate. Differences were smaller and nonsignificant for protein density. Food frequencies, records, and recalls were, respectively, able to “explain” 3.8%, 7.8%, and 2.8% of biomarker variation for energy; 8.4%, 22.6%, and 16.2% of biomarker variation for protein; and 6.5%, 11.0%, and 7.0% of biomarker variation for protein density. However, calibration equations that include body mass index, age, and ethnicity substantially improve these numbers to 41.7%, 44.7%, and 42.1% for energy; 20.3%, 32.7%, and 28.4% for protein; and 8.7%, 14.4%, and 10.4% for protein density. Calibration equations using any of the assessment procedures may yield suitable consumption estimates for epidemiologic study purposes

Increases in physical activity may affect quality of life differently in men and women: The PACE project

PURPOSE: Obesity is associated with impaired quality of life (QoL), but less is known about physical activity. We investigated how decreases in body mass index (BMI) and increases in activity affect obesity-specific QoL and potential gender differences in associations. METHODS: In a large worksite-randomized trial of a multilevel intervention on diet and physical activity behaviors, we conducted a cohort analysis at two years of follow-up. Self-reported activity and Obesity and Weight-Loss Quality Of Life (OWLQOL) were analyzed for individual-level associations using linear mixed models accounting for random worksite effects. RESULTS: Gender modified the BMI-OWLQOL relationship, so analyses were conducted for males and females separately. Adjusting for demographic confounders, baseline OWLQOL, and several worksite-level variables including intervention arm, a 1.9 unit decrease in BMI (the interquartile range) was associated with an OWLQOL increase of 1.7 (95% CI: 1.2, 2.2) in males and 3.6 (95% CI: 3.2, 4.0) in females. Similarly, a 23 unit increase in physical activity score was associated with an OWLQOL increase of 0.9 (95% CI: 0.5, 1.4) in males and 1.6 (95% CI: 1.0, 2.3) in females. Physical activity associations were attenuated when adjusting for change in BMI, but remained significant for women (mean BMI 27.8 kg/m(2)). CONCLUSIONS: This is the first study to demonstrate that increasing physical activity may improve obesity-specific QoL to a greater extent in women, particularly among overweight women, independent of BMI. Results may inform the design of interventions tailored to women targeting well-being through messages of increasing physical activity

Estimating Pesticide Exposure from Dietary Intake and Organic Food Choices: The Multi-Ethnic Study of Atherosclerosis (MESA)

Background: Organophosphate pesticide (OP) exposure to the U.S. population is dominated by dietary intake. The magnitude of exposure from diet depends partly on personal decisions such as which foods to eat and whether to choose organic food. Most studies of OP exposure rely on urinary biomarkers, which are limited by short half-lives and often lack specificity to parent compounds. A reliable means of estimating long-term dietary exposure to individual OPs is needed to assess the potential relationship with adverse health effects. Objectives: We assessed long-term dietary exposure to 14 OPs among 4,466 participants in the Multi-Ethnic Study of Atherosclerosis, and examined the influence of organic produce consumption on this exposure. Methods: Individual-level exposure was estimated by combining information on typical intake of specific food items with average OP residue levels on those items. In an analysis restricted to a subset of participants who reported rarely or never eating organic produce (“conventional consumers”), we assessed urinary dialkylphosphate (DAP) levels across tertiles of estimated exposure (n = 480). In a second analysis, we compared DAP levels across subgroups with differing self-reported organic produce consumption habits (n = 240). Results: Among conventional consumers, increasing tertile of estimated dietary OP exposure was associated with higher DAP concentrations (p < 0.05). DAP concentrations were also significantly lower in groups reporting more frequent consumption of organic produce (p < 0.02). Conclusions: Long-term dietary exposure to OPs was estimated from dietary intake data, and estimates were consistent with DAP measurements. More frequent consumption of organic produce was associated with lower DAPs. Citation Curl CL, Beresford SA, Fenske RA, Fitzpatrick AL, Lu C, Nettleton JA, Kaufman JD. 2015. Estimating pesticide exposure from dietary intake and organic food choices: the Multi-Ethnic Study of Atherosclerosis (MESA). Environ Health Perspect 123:475–483; http://dx.doi.org/10.1289/ehp.140819

Life’s Simple 7 and Incidence of Diabetes Among American Indians: The Strong Heart Family Study

OBJECTIVE: The American Heart Association’s recommendations for optimal health, summarized in Life’s Simple 7, have been associated with reduced risk of cardiovascular disease (CVD)-related end points, but no studies have examined the association of these goals with incident type 2 diabetes, which is associated with high risk for CVD. The purpose of this analysis was to examine the associations of Life’s Simple 7 goals with incident diabetes among American Indians, a population at high risk of cardiometabolic diseases. RESEARCH DESIGN AND METHODS: Strong Heart Family Study participants without diabetes (n = 1,639) at baseline and who participated in a follow-up examination were included in the analysis. Risk scores ranging from 0 to 7 were created using physical activity, diet, BMI, smoking, blood pressure, fasting glucose, and cholesterol metrics in accordance with Life’s Simple 7 goals. Diabetes was defined using 2003 American Diabetes Association criteria, including use of insulin or oral antidiabetes medication or a follow-up fasting plasma glucose level ≥126 mg/dL. Generalized estimating equations were used to examine the association of risk scores with incident diabetes. RESULTS: During a mean 5-year follow-up (range 4–8 years), we identified 210 cases of incident type 2 diabetes. Compared with participants who achieved 0–1 goals, those who achieved 2–3 or 4+ goals had lower odds of diabetes, with odds ratios = 0.40 (95% CI 0.29–0.56) and 0.11 (95% CI 0.05–0.21), respectively. CONCLUSIONS: The adoption of as few as two or three Life’s Simple 7 goals is associated with a lower risk of diabetes