Study design
Observational Study
The IGNITE trial was designed as a prospective observational cohort study [15]. Data collection instruments assessed theoretical dimensions shared by four large reviews of the implementation literature [16–19]. Some potential determinants, such as financial incentives and training/technical support were not options or uniformly applied across sites, respectively, and not included in the model. The mediators for the second phase of the model (program exposure/dose to outcomes) were assessed in the original PHLAME efficacy trial mediation analysis [20], and we focused on a simplified model with program exposure leading directly to participant outcomes. Different terms have been used to describe the process of how a program is used [21]. We chose to call the proximal variable between implementation constructs and outcomes “exposure.” In some cases, that term has related only to participant awareness [22]. However, as we only had self-reported measures of fidelity and session duration, we used the more general term, with a meaning more akin to “implementation effectiveness,” which concerns participants’ aggregate use [23]. To enhance understanding and explore features not captured by this model, a parallel qualitative analysis used group interviews [24]. Study method and reported findings adhere to components of the STROBE Statement for observational studies [25]. The institutional review board of the Oregon Health & Science University approved the study in August of 2009.
Site recruitment and adoption
Information about the study was mailed to all (n=70) medium-sized fire departments (40–140 career firefighters) in Oregon and Washington, and 19 agreed to participate. Twelve sites were selected to provide a spectrum of contextual variables. This number was predicted as sufficient to detect effects where paths to or from purported mediators were medium or larger. Each selected site provided assurance that its firefighters were informed about the program and a tentative agreement that the majority would voluntarily participate. Additional details concerning recruitment and the decision to adopt are described separately [26].
Data collection
Reflecting the three 24-h shift structure, each site was assessed over 3 days in late spring 2010, during which consents were obtained, surveys completed, limited physiological data acquired (height, weight), and group interviews conducted. Following data collection, PHLAME materials were distributed, and shifts were oriented to conducting the program. Technical support was available to all sites throughout the study. Approximately 6 months later, the initial data gathering activities were repeated during a second round of 3-day visits. Follow-up assessments included program exposure indexed as the participant self-reported session completion, using cued recall of session content; the survey and group interviews included additional items relating to the program’s characteristics and use.
Survey data were used to identify firefighter demographics and dietary indices [27]. Firefighters’ self-reported general health was measured with the ‘General Health’ subscale of the SF-36 instrument [28]. Additional items were selected from existing instruments to assess components of the hypothesized translational model, including organizational climate [29, 30], leadership characteristics [31], and items relating to program scheduling/competing demands and tailoring. The survey construct items were answered using a seven-point agreement scale. Individual items for the constructs are shown in Table