The hybrid design of the Think Health! Study combines objectives that prioritize internal validity (as in efficacy studies) with those that explore feasibility and give more priority to external validity and potential sustainability (as in effectiveness studies) [36
]. This type of trial is a useful precursor to a practical trial that would require full adoption and institutionalization within primary care settings. Clinical site recruitment focused on community-based practices, most of which had little previous involvement in research or in lifestyle change research. The five participating practices included the two major primary care specialties (internal medicine and family medicine) and were also diverse with respect to organizational structures, size, and longevity. Targeting African Americans and Hispanics at the practice level, and emphasizing the importance of including these groups from a research perspective, was effective; 81% of randomized participants were members of one of these two groups. The percent of male participants recruited was lower than desired for generalizability. Men are typically underrepresented in weight loss programs [3
], and men make fewer visits than women to primary care physicians [38
]. Hypertension, the most common obesity-related comorbidity in our sample, is also the most common diagnosis associated with primary care visits [38
The major study challenge in the start-up phase was the time needed to complete the process of negotiating participation agreements for the required number of sites. Ellis and colleagues, based on analyses of yield and cost associated with 10 strategies used to recruit primary care practices to a randomized trial related to cardiovascular disease risk factor management, reported that in-person meetings and previous relationships were the most cost efficient [39
]. These are essentially the strategies that we used, but the time needed for the decision making process at practices was quite extended, except for the independent practice, in which all decisions were made within the practice itself. This delay may raise a crucial issue for lifestyle change interventions in primary care, for which the time commitment of clinicians and involved ancillary staff is presumably greater than for pharmacologic interventions. The compensation we offered was sufficient for some incentives for existing staff, but not enough to allow practices to increase their staff.
The legislation authorizing the Think Health! study funding required that all project funds be used within 4 years. The delay in beginning patient recruitment required that the protocol be revised to allow for administrative censoring as early as 16 months post randomization, rather than follow all participants for 24 months as originally intended. Once underway, patient recruitment was completed in a timely manner. Advertising the study practice-wide (e.g., in waiting and exam rooms) might have shortened the time needed for patient recruitment. However, in Think Health! this was only appropriate for the site in which both clinicians were engaged in the study.
In conclusion, studies to identify effective models for obesity treatment in primary care offices are generally lacking and are especially needed for ethnic minority adults who, on average, have a higher risk of obesity-related chronic diseases than whites [6
]. A systematic review of randomized controlled trials in which behavioral weight loss interventions were provided in primary care identified only 10 qualifying RCTs [4
]. Four studies were based on brief PCP lifestyle counseling without adjunctive medication, of which one involved primarily African Americans (low-income women) [40
] and one included 50% Latinos with type 2 diabetes [41
]. The logistical and feasibility aspects of studies conducted in natural settings such as primary care practices differ from those in studies in which researchers maintain control over the process and alter natural settings to align with research needs. The Think Health! study is designed to determine what might be possible when a simplified version of the Diabetes Prevention Program lifestyle intervention is delivered individually to primary care patients with minimal departures from an approach that is potentially replicable in usual care settings that reach high risk ethnic minority adults.