Using multilevel analysis, this study investigated participant and site characteristics associated with participant retention in a multisite diabetes prevention translational project among American Indian and Alaska Native (AI/AN) people. We analyzed data from the Special Diabetes Program for Indians Diabetes Prevention Program (SDPI-DP), a lifestyle intervention to prevent diabetes implemented in 36 AI/AN grantee sites. A total of 2,553 participants were recruited and started the intervention between January 1, 2006 and July 31, 2008. They were offered the 16-session Lifestyle Balance Curriculum from the Diabetes Prevention Program (DPP) in the first 16-24 weeks of intervention. Generalized estimating equation models and proportional hazards models with robust standard error estimates were used to evaluate the relationships of participant and site characteristics with retention. As of July 31, 2009, about 50 % of SDPI-DP participants were lost to follow-up. Those who were younger, male, with lower household income, no family support person, and more baseline chronic pain were at higher risk for both short-term and long-term retention failure (i.e., not completing all 16 DPP sessions and loss to follow-up, respectively). Sites with large user populations and younger staff had lower likelihood of retaining participants successfully. Other site characteristics related to higher risk for retention failure included staff rating of participant disinterest in SDPI-DP and barriers to participant transportation and child/elder care. Future translational initiatives need to pay attention to both participant- and site-level factors in order to maximize participant retention.

The association of psychosocial factors (psychological distress, coping skills, family support, trauma exposure, and spirituality) with initial weight and weight loss among American Indians and Alaska Natives (AI/ANs) in a diabetes prevention translational project was investigated. Participants (n = 3,135) were confirmed as prediabetic and subsequently enrolled in the Special Diabetes Program for Indians Diabetes Prevention (SDPI-DP) demonstration project implemented at 36 Indian health care programs. Measures were obtained at baseline and after completing a 16-session educational curriculum focusing on weight loss through behavioral changes. At baseline, psychological distress and negative family support were linked to greater weight, whereas cultural spirituality was correlated with lower weight. Furthermore, psychological distress and negative family support predicted less weight loss, and positive family support predicted greater weight loss, over the course of the intervention. These bivariate relationships between psychosocial factors and weight remained statistically significant within a multivariate model, after controlling for sociodemographic characteristics. Conversely, coping skills and trauma exposure were not significantly associated with baseline weight or change in weight. These findings demonstrate the influence of psychosocial factors on weight loss in AI/AN communities and have substantial implications for incorporating adjunctive intervention components.

Participant attrition in clinical trials and community-based interventions is a serious, common, and costly problem. In order to develop a simple predictive scoring system that can quantify the risk of participant attrition in a lifestyle intervention project, we analyzed data from the Special Diabetes Program for Indians Diabetes Prevention Program (SDPI-DP), an evidence-based lifestyle intervention to prevent diabetes in 36 American Indian and Alaska Native communities. SDPI-DP participants were randomly divided into a derivation cohort (n = 1600) and a validation cohort (n = 801). Logistic regressions were used to develop a scoring system from the derivation cohort. The discriminatory power and calibration properties of the system were assessed using the validation cohort. Seven independent factors predicted program attrition: gender, age, household income, comorbidity, chronic pain, site's user population size, and average age of site staff. Six factors predicted long-term attrition: gender, age, marital status, chronic pain, site's user population size, and average age of site staff. Each model exhibited moderate to fair discriminatory power (C statistic in the validation set: 0.70 for program attrition, and 0.66 for long-term attrition) and excellent calibration. The resulting scoring system offers a low-technology approach to identify participants at elevated risk for attrition in future similar behavioral modification intervention projects, which may inform appropriate allocation of retention resources. This approach also serves as a model for other efforts to prevent participant attrition.

Objective

To investigate possible socioeconomic disparities in weight and behavioral outcomes among American Indian and Alaska Native (AI/AN) participants in a translational diabetes prevention project.

Research design and methods

We analyzed data from the Special Diabetes Program for Indians Diabetes Prevention (SDPI-DP) Program, an evidence-based lifestyle intervention to prevent diabetes in 36 AI/AN grantee sites. A total of 2,553 participants started the 16-session Lifestyle Balance Curriculum between 1 January 2006 and 31 July 2008. Linear mixed models were used to evaluate the relationships of participant and staff socioeconomic characteristics with weight and behavioral outcomes at the end of the curriculum.

Results

A strong, graded association existed between lower household income and less BMI reduction, which remained significant after adjusting for other socioeconomic characteristics. Compared with others, participants with annual income <$15,000 also had less improvement in physical activity and unhealthy food consumption in bivariate models, but the relationships were only marginally significant in multivariate regressions. Furthermore, grantee sites with fewer professionally prepared staff were less successful at improving participant BMI and healthy food consumption than the other sites. The strong association between income and BMI reduction was reduced by 20-30% in the models with changes in diet variables but was unrelated to changes in physical activity.

Conclusions

Significant socioeconomic disparities exist in weight outcomes of lifestyle intervention at both participant and site staff levels. Helping low-income participants choose more affordable healthy foods and increasing the proportion of professionally trained staff might be practical ways to maximize the effectiveness of lifestyle interventions implemented in "real-world" settings.