© 2004 American Public Health Association
Elizabeth J. Mayer-Davis, Angela M. DAntonio, Sharon M. Smith, and Richard Schulz are with the Arnold School of Public Health, Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC. Gregory Kirkner is an independent consultant in Milton, Mass. Sarah Levin Martin is with the Physical Activity and Health Branch, Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, Atlanta Ga. Deborah Parra-Medina is with the Department of Health Promotion, Education and Behavior, Arnold School of Public Health, and the Department of Womens Studies, University of South Carolina, Columbia, SC. Elizabeth J. Mayer-Davis also is with the Center for Research in Nutrition and Health Disparities, University of South Carolina. Richard Schulz also is with the College of Pharmacy, Department of Pharmaceutical and Health Outcomes Sciences, University of South Carolina. Correspondence: Requests for reprints should be sent to Elizabeth J. Mayer-Davis, PhD, Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208 (e-mail: mayer{at}gwm.sc.edu).
Objectives. We evaluated lifestyle interventions for diabetic persons who live in rural communities. Methods. We conducted a 12-month randomized clinical trial (n = 152) of "intensive-lifestyle" (modeled after the NIH Diabetes Prevention Program) and "reimbursable-lifestyle" (intensive-lifestyle intervention delivered in the time allotted for Medicare reimbursement for diabetes education related to nutrition and physical activity) interventions with usual care as a control. Results. Modest weight loss occurred by 6 months among intensive-lifestyle participants and was greater than the weight loss among usual-care participants (2.6 kg vs 0.4 kg, P<.01). At 12 months, a greater proportion of intensive-lifestyle participants had lost 2 kg or more than usual-care participants (49% vs 25%, P<.05). No differences in weight change were observed between reimbursable-lifestyle and usual-care participants. Glycated hemoglobin was reduced among all groups (P<.05) but was not different between groups. Conclusions. Improvement in both weight and glycemia was attainable by lifestyle interventions designed for persons who had type 2 diabetes and lived in rural communities.
Individuals who live in rural medically underserved communities are an important target population for translational research. Such research evaluates interventions that are designed and implemented for various population settings on the basis of efficacy established during previous randomized controlled trials. In South Carolina, 75% of counties are designated as "medically underserved" by the US Public Health Service,1 and the prevalence of overweight, obesity, and physician-diagnosed diabetes is among the highest in the nation.2 Approximately 30% of the state population is Black, and among Black adults who have type 2 diabetes, glucose control as indicated by glycated hemoglobin (HbA1c) has been shown to be considerably higher than among White adults (10.5% vs 8.4%).3 Previous clinical trials have shown that among persons who have type 2 diabetes, moderate weight loss can improve glycemic control and lipoprotein profile and reduce blood pressure.46 Although definitive data on the benefits of long-term weight loss to reduce risk for clinical complications of diabetes are not yet available, the evidence-based nutrition recommendations of the American Diabetes Association emphasize the importance of weight management as a key element of medical nutrition therapy for diabetes. The American Diabetes Association also emphasizes the importance of glycemic control and management of cardiovascular risk factors, regardless of weight status.7 Among urban Black populations, including those who have diabetes, the success of culturally sensitive behavioral weight loss programs has been reported,5,812 although some studies reported that, compared with Whites, Blacks lost less weight10 and had an increased tendency to regain weight.11 To date, only a limited number of studies of behavioral programs for persons who have type 2 diabetes have been conducted in rural or semirural communities, where improvements in glycemic control and weight loss varied.1316 The goal of our study was to develop, implement, and evaluate a 1-year primary carebased lifestyle intervention for weight management that was designed to improve metabolic control among individuals who have type 2 diabetes and live in rural medically underserved communities. The state-of-the art lifestyle intervention program developed for the National Institutes of Healthfunded Diabetes Prevention Program (DPP),17 in combination with experiences gained from an 8-week pilot study13 and focus groups, was used to guide the planning and the implementation of our 12-month randomized controlled trial ("intensive-lifestyle" intervention). Because of the limited amount of time for health education that is normally reimbursed by health insurance, we evaluated a second weight management strategy. It was designed to deliver the most salient elements of the intensive-lifestyle intervention within the approximate number of hours that are usually reimbursed by Medicare for 12-month nutritional education among persons who have recently been diagnosed with diabetes ("reimbursable-lifesyle" intervention).
Setting Our 12-month randomized clinical trialPOWER (Pounds Off With Empowerment)was a collaborative effort between the University of South Carolina and the South Carolina Primary Health Care Association, which represents the federally funded primary health care facilities in the state that provide care to medically underserved communities. Two primary health care centers in rural counties were identified on the basis of large numbers of patient visits for diabetes care. Both health centers were provided with subcontracts that covered the costs of implementing the study on-site, including funds for hiring study staff and for providing transportation to study participants. Thus, the project was highly visible and was integrated into the daily operations of the health centers.
Participant Eligibility and Recruitment Of the 664 potential participants contacted by phone, 143 (21.5%) were randomized into the study, which was similar to the recruitment yield in university-based behavioral trials.19 Another 53 participants attended the initial screening visit on the basis of response to local publication efforts (posters, etc.), and 46 (87%) of these were randomized. Two of the 189 randomized participants were subsequently excluded because of severe congestive heart failure; thus, 187 participants were included in the trial.
Intervention For our study, we made modifications to the DPP intervention on the basis of an 8-week pilot study13 and findings from 2 focus groups. Modifications included regular use of group sessions, considerable simplification and reduction in the amount of written materials, encouragement of physical activity at low to moderate intensity for individuals who had very sedentary lifestyles, and inclusion of additional regionally/culturally appropriate examples, such as modifications of regularly consumed foods (e.g., substitute turkey neck bone for ham bone to cook greens, low-fat seasoning for grits) and suggestions for physical activity (e.g., identification of safe places to walk in the community, use of chair exercises for individuals who had lower-extremity pain). Self-monitoring tools for diet and physical activity were retained in a very simple format. Information regarding selected aspects of diabetes care (e.g., encouragement to monitor blood glucose at home) was incorporated, although the intervention retained a clear focus on diet and physical activity. Intensive-lifestyle participants met weekly with the study nutritionist for delivery of the first 4 months of the core curriculum (intensive), every other week for the next 2 months (transition), and once a month for the remaining 6 months (maintenance). Nutritionists delivered both the nutritional and the physical activity components of the intervention within these scheduled 1-hour sessions. Sessions were modeled after the NIH-funded Trial of Non-Pharmacologic Interventions in the Elderly20 and were conducted sequentially in a pattern of 3 group sessions and 1 individual session. The reimbursable-lifestyle intervention was a condensed version of the intensive-lifestyle intervention, in which key elements of the intensive-lifestyle intervention were delivered in 4 1-hour sessions over the course of the 12-month study and included 3 group sessions and 1 individual session. The total time allotted for delivery of this intervention was determined by the approximate number of hours reimbursed annually by Medicare for diabetes education (diet and physical activity) in South Carolina for an individual who was recently diagnosed with diabetes. Usual care was delivered in 1 individual session by a study nutritionist at the beginning of the 12-month period. Information related to diet and physical activity was derived from materials developed by the American Diabetes Association and the American Dietetic Association.
Outcome Measures Secondary outcomes included HbA1c (marker of glycemic control), lipid profile, and blood pressure. Laboratory assays of glycated hemoglobin, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, and low-density lipoprotein (LDL) cholesterol were conducted at the Analytic Chemistry Laboratory of the South Carolina Department of Health and Environmental Control with the Boehringer Mannheim (Hitachi 911 Analyzer; Roche Diagnostics, Indianapolis, Ind). These assays were conducted during the randomization and 6-month visits only. Blood pressure was measured 3 times with a standard mercury sphygmomanometer (appropriate cuff sizesadult regular, large arm, or thighwere used); the averages of the second and third readings for systolic and diastolic pressure were included in the statistical analysis.
Quality Control
Statistical Analysis Intervention effects were first evaluated with paired t tests within each randomization group. Potential differences between intensive-lifestyle intervention and usual care and between reimbursable-lifestyle intervention and usual care were evaluated with linear regression modeling of weight change that accounted for clinical site and for change in use of prescribed diabetes medication (insulin, metformin, and other oral hypoglycemic agents) during the course of the 1-year intervention period. Models did not require adjustment for education, gender, or age because these did not differ significantly between randomization groups at baseline. Additionally, between-group differences were evaluated with random effects and repeated-measures regression models in SAS PROC MIXED (SAS Institute Inc, Cary, NC), with specification of random clinic effects within random subject effects that allowed for missing values from follow-up visits. These results were essentially the same as those from the simpler regression modeling; therefore, the regression model results are presented in the results section. Because of the skewed distribution of plasma triglyceride values, analyses of triglycerides were conducted with a natural log transformation. To eliminate the possibility of health center differences in intervention delivery, we tested the interaction between clinic and randomization group, and no such interactions were detected. Finally, analyses were repeated in the subgroup of study participants ("high attendees") who attended at least 50% of the core curriculum and transitional sessions for intensive-lifestyle intervention (n = 36) or at least 2 of the 4 sessions for reimbursable-lifestyle intervention (n = 47).
Sample Characteristics Of the 187 participants, 152 (81%) were retained through the 12-month end-of-study measurement visit. Baseline characteristics of these 152 individuals are shown in Table 1
Primary Outcome Figure 1
To more fully understand patterns of weight change in this trial, 3 categories were defined arbitrarily as "gained 2 or more kg," "stable weight (within 2 kg)," and "lost 2 or more kg"; results are shown in Figure 2 2 statistic, P < .05). Reimbursable-lifestyle participants did not differ significantly from usual-care participants in these analyses.
Secondary Outcomes Figure 3
Although most of the secondary metabolic outcomes we evaluated improved modestly among all 3 groups (Table 2
Analyses Restricted to "High Attenders" Of the 49 individuals in the intensive-lifestyle intervention, 36 (73%) attended at least 50% of the core curriculum and transition sessions, and all 47 individuals in the reimbursable-lifestyle intervention attended at least 2 of the 4 sessions; all usual-care participants were included for comparison. Among the intensive-lifestyle "high attenders," mean weight loss at 6 and 12 months was 3.1 kg (P < .001 compared with usual-care participants) and 2.7 kg (P < .05 compared with usual-care participants), respectively.
The POWER study was conducted as a translational research project designed to evaluate the effectiveness of a state-of-the-art lifestyle intervention for weight management and metabolic control of diabetes. It was applied to older adults, primarily Black, who had physician-diagnosed type 2 diabetes and lived in rural medically underserved communities in South Carolina. Modest weight loss occurred at 6 months and was statistically significantly greater among the intensive-lifestyle participants compared with the usual-care participants. At 12 months, a significantly greater proportion of intensive-lifestyle participants compared with usual-care participants had lost at least 2 kg. No statistically significant weight loss was observed among reimbursable-lifestyle participants. Men were less likely to regain lost weight, although this result should be reviewed with considerable caution because of the small number of men in the intensive-lifestyle group (n = 11). Differences between groups in lipid profile and blood pressure were not statistically significant; however, glycemic control measured by HbA1c improved among all 3 groups.
Weight Loss and Metabolic Status The potential relevance of the observed improvement in HbA1c among the intensive-lifestyle participants (1.6%) is evident from controlled clinical trials in which glycemic control was predictive of risk for microvascular complications, including diabetic retinopathy and nephropathy.25,26 Additionally, prospective epidemiologic analyses have estimated that each 1% reduction in HbA1c was associated with a 14% reduction in risk for myocardial infarction and a 21% risk reduction for death related to diabetes.27 Agurs-Collins et al.5 found that HbA1c was reduced from 11.0% to 9.9% among the weight loss intervention group compared with an increase of 10.0% to 11.5% among the control group (P < .05). Change in HbA1c was not statistically attributable to weight loss and was presumed to have improved as a result of improved diabetes self-management that may have occurred as an indirect benefit of the intervention. Among POWER participants, neither prescribed medication regimen nor weight change was predictive of improved HbA1c. While the POWER trial was ongoing, a "diabetes collaborative" was introduced into both of the clinic sites as part of a federally funded effort to improve chronic disease management among community health center patients. Thus, improvement in day-to-day diabetes management, including consistency in taking prescribed diabetes medication and monitoring blood glucose at home, may have accounted for the improved glycemic control.28 Additionally, individuals who were willing to participate in this 1-year clinical trial may have been inherently motivated to make the needed day-to-day diabetes management changes. Certainly, improvement in HbA1c among usual-care participants was a welcome finding, but it likely precluded identification of a statistically significant difference between usual-care and intensive-lifestyle participants. With regard to lipid profile and blood pressure, improvements were modest and, like the work of Agurs-Collins et al.,5 were generally nonsignificant. Similarly, a 1-year trial of a culturally sensitive weight management intervention among Black women (n = 529 from 16 churches) demonstrated modest but statistically significant weight loss differences (1.1 kg for intervention vs 0.83 kg for control) but no statistically significant difference between intervention and control for lipids or blood pressure.29 Previous studies that demonstrated statistically significant improvement in these parameters in the context of a weight loss intervention were conducted either among persons who did not have diabetes,30 who had a greater amount of weight loss,31 or both. Thus, given the modest weight loss among POWER participants and the relatively small sample size, it was not surprising that statistically significant improvements in lipid profile or blood pressure were not detected. Wing et al.4 demonstrated a doseresponse effect of weight loss on these metabolic outcomes; therefore, it is reasonable to assume that modest weight loss may confer some degree of health benefit.
Potential Barriers to Health Action
Comprehensive intervention approaches that address documented barriers to sustained behavior change for weight management and diabetes self-management for individuals living in rural communities are needed. In particular, the important barrier of payment for professional contact time and for transportation to receive services must be addressed. With POWER, we have documented that modest weight loss and improved glycemic control is attainable by culturally appropriate state-of-the-art lifestyle interventions among Black and White individuals who have type 2 diabetes and live in rural medically underserved communities. We also have shown that the same intervention approach, when delivered in the amount of time normally reimbursed by health insurance (i.e., 45 hours over 12 months), was not effective in terms of weight loss; however, some improvement in glycemic control was noted. For persons who have diabetes and live in rural medically underserved communities, future translational research should focus on comprehensive approaches to diabetes management and education and should be designed to elicit greater improvement in metabolic status and health-related quality of life. Likely, focusing on medication compliance, monitoring blood glucose at home, and other aspects of diabetes self-care will be important. Additionally, future research should address the limited numbers of health care providers in rural communities. Use of telemedicine technology, including interactive videoconferencing and Internet support, should be considered. Future studies also should consider health insurance and associated health policy and cost to ensure a means of delivering services that are effective in rural settings.
Funding for this project was made possible by the Centers for Disease Control and Prevention in Atlanta, Ga (grant #U48/CCU40966407). We thank the leadership of the South Carolina Primary Health Care Association; the Family Health Centers in Orangeburg, SC; and Care South Carolina in Hartsville, SC. We also thank the NIH-funded Diabetes Prevention Program for making the lifestyle intervention materialsfrom which the POWER interventions were modeledavailable to us.
Human Participant Protection
Contributors E. J. Mayer-Davis conceived the study, supervised all aspects of the study implementation, and led the writing. A. M. DAntonio was the lead nutritionist, was instrumental in the delivery of the intervention, and contributed to the analysis and writing. S. M. Smith contributed to the data collection, analysis, and writing. G. Kirkner was the data manager and assisted with the study and analysis. S. Levin Martin was the project manager and directed the daily aspects of the study. D. Parra-Medina assisted with the study design and the recruitment and retention of participants. R. Schultz assisted with the study design and direction of the study. Accepted for publication September 12, 2003.
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