Building a Life Course Intervention Research Framework

The LCIRN is a collaborative network of ∼75 active members committed to improving life course trajectories and outcomes for children and families using an LCHD approach (https://lcirn.ucla.edu). The National Coordinating Center (NCC) is based at the University of California, Los Angeles, with 2 research cores (family and community engagement, and race, place, class and gender), and 9 current research nodes tackling adversity and resilience, attention-deficit/hyperactivity disorder (ADHD), early childhood mental health, family health development, measurement of family functioning, school health, success after prematurity, youth justice, and youth-led participatory action research at institutions across the United States.

Discussions around developing a research methodology and framework informed by intervention research and anchored in life course theory began at an LCIRN meeting in 2019 attended by forty members, including steering committee and advisory board representatives. Following the meeting, a core team of 4 researchers at the NCC reviewed existing models and frameworks for intervention research that could be readily adapted or applied to LCIR, with the initial emphasis on identifying a comprehensive framework for intervention research that could be added to or adapted for life course interventions. These interventions are rarely simple. They are frequently multilevel and equity-focused, requiring different intervention approaches in different circumstances and contexts. Thus, a comprehensive intervention framework was needed that is designed to incorporate more complex and innovative interventions and to facilitate codesign processes with stakeholders and researchers. Following a literature review and iterative discussion within the core team the NCC identified the “Guidance on how to develop complex interventions to improve health and healthcare”¹⁸  based in part on a revised and expanded Medical Research Council Framework,^19,20  and informed by a systematic methods review²¹  and stakeholder interviews.²²  This comprehensive guidance breaks down intervention research into >15 discrete areas or tasks, starting with conception of the problem and planning of the study, and moving through design, implementation, testing, evaluation, and spread. This detailed framework appeared readily adaptable to LCIR.

The NCC developed version (A) of the Life Course Intervention Research Framework (LCIRF), combining the 7 original LCHD principles (health development, unfolding, complexity, timing, plasticity, thriving and harmony)³  with an adapted version of O’Cathain’s guidance¹⁸  (Table 1). Although all principles should apply to all stages, for simplicity, Table 1 lists just 2 to 4 LCHD principles for each step. The LCIRN steering committee operationalized and expanded these LCHD principles into 12 characteristics of life course interventions through an iterative collaborative process, including a Modified Delphi review, that has been reported on separately.¹⁷  These 12 characteristics were more comprehensible in plain language and more actionable in real-life interventions. Mindful that the framework needed to be sufficiently robust to guide research, yet also easily useable by youth, family, and community partners, the group streamlined it into 5 stages: conception and planning, design, implementation, evaluation, and translation.

The 15 members of the steering committee also identified 12 additional approaches, models, or frameworks with elements relevant to the LCIRF. The NCC reviewed the models and summarized their main components (Table 2). Steering committee members and NCC Core members suggested elements from the models that they felt were key for inclusion in a comprehensive LCIR framework. They based their recommendations on their experience and on their understanding of emerging directions in the literature and suggested ways in which these elements might be incorporated. Members of the core team also consulted with researchers with expertise in Youth-led Participatory Action Research (YPAR) and Community-Based Participatory Research (CBPR) to better understand potential links with LCIR. Following this process, the NCC core team incorporated key elements from these additional models to create the LCIRF(B) that delineates the steps in the 5 stages (Fig 1 A-C).

LCIRF(B) was further simplified and combined with the 12 characteristics of life course interventions to produce an actionable version, the LCIRF(C) (Table 3). Table 3 considers the entire process of LCIR and is designed to be used together with Fig 1 A-C. For example, researchers in the planning stage can consult both Fig 1A and the first column in Table 3 for detailed steps and ways to apply life course characteristics to research conceptualization and planning.

LCIRF(A) (Table 1) breaks down the process of developing an intervention from initial conceptualization to eventual spreading and scaling through 16 steps, each of which requires attention to detail, documentation, and funding. Researchers are prompted to consider the principles of LCHD at each stage as they design their intervention and study.

Table 2 lists additional intervention research approaches and models that influenced framework development. These include community-based participatory research,²⁴  youth-led participatory action research,²⁶  and action research.^24,25  These approaches incorporate active roles for youth, family, and community representatives as partners with transdisciplinary teams of researchers and administrators, adding their expertise both in terms of lived experience of an issue or condition, and deep contextual understanding of the environments in which the interventions will be implemented. The inclusion of these approaches into the LCIRF resonates with the concept of human-centered design; the intervention being designed with the end-user in mind from the beginning. Engaging a diverse set of “users” from the start should facilitate the eventual spreading and scaling of successful interventions, avoiding “boutique” interventions that only work for a limited proportion of the population. These approaches drove the evolving LCIRF toward inclusion of youth, family, and community voices at every stage of intervention development, rejecting models in which pivotal decisions were taken by professional groups working alone with community groups brought in later.

The National Institute of Health Stage Model²⁷  and Five Phase Model²⁸  group the steps of intervention research into a series of stages or phases, with each step informing the next until lessons learned from the final stages suggest new problems that need to be studied, feeding back into new topics for basic research. The adaptive interventions,²⁹  Just-In-Time Adaptive Interventions,³¹  and Sequential Multiple Assignment Randomized Trials (SMART) trial designs³⁶  provide options to tailor studies to different populations and levels of need, considering individual circumstances, intervention context, and for SMART trials, each individual’s initial response to an intervention.³⁶  They allow more flexibility in intervention delivery, meeting people where they are, and potentially moving to a model where each subject of an intervention could be engaged in an iterative process with researchers navigating through a series of intervention decisions informed both by expert opinion and client preference, yet still conducted with sufficient rigor to yield meaningful data and conclusions.

Roger’s Diffusion of Innovation Model^32,33  and the Model for Improvement³⁴  are of most relevance for late-stage efficacy and effectiveness studies, and for scaling and spreading strategies for successful interventions. These later stages of intervention research blur the boundaries between implementation science and quality improvement models. Although randomized control trails (RCTs) can still be employed at this stage, many implementation science questions are best addressed through quasi-experimental designs including pre and post, interrupted time series, and stepped-wedge designs where all participants receive the intervention, but in a staggered fashion.³⁷ 

Now informed by the additional models, intervention steps were grouped into 5 main stages, each with key steps and activities: (1) conceptualization and planning, (2) design, (3) implementation, (4) evaluation, and (5) translation or spread and scale. Figures 1–3 provide detail on activities and other considerations at each stage.

The third and current version, LCIRF(C) (Table 3) applies the 12 characteristics of life course interventions¹⁷  to the 5 stages of LCIR.

There is growing consensus that most contemporary public health challenges, especially health inequities, are so-called “wicked” problems³⁸  not amenable to simple medical or pharmacological solutions.³⁹  This has led to interest in complex, multilevel, and sustained intervention approaches that are adaptive and responsive to changing circumstances. The LCHD approach^1,2  brings a complex adaptive system perspective⁴⁰  to intervention research. Each person’s physical, mental, socio-emotional, and spiritual health results from multiple risk and protective factors operating throughout the lifespan,^1,2  and the impact of those factors varies based on the life stage and context. Consequently, interventions designed to address these health issues must impact multiple risks, operate at strategic times, and be responsive to lived context.

Health equity from the start of life must be a public health priority, as small differences and disadvantages early on tend to compound over time, leading to larger and more intractable problems later.⁴¹  A purposeful focus on equity from the start means designing life course interventions to correct emerging health issues early, while also supporting each child’s health development capabilities, building resilience and reserves into their health development trajectories from the start.⁴²  This approach expands on the health promotion efforts of the past but goes further, treating the development of health as an active process in which protective actions, experiences, and exposures build on each other across developmental stages.

The LCHD model also aims to serve as an organizing framework for addressing social determinants of health. Long understood to have a profound impact on health, factors such as relationships, economic stability, education, health care access, and neighborhood environment⁴³  have traditionally been regarded as outside the purview of clinicians. While a full discussion of all the possible categorizations of social determinants is beyond the scope of this paper, it is of note that contemporary researchers expand this list to include the “structural determinants of health,”⁴⁴  including racism, classism, and gender discrimination as powerful drivers of health development pathways and hence, as appropriate targets for LCIR.

Interventions to equitably improve health across the life course can and must address these broader levels of influence if they are to be effective. No single intervention can address all of these levels and factors, but LCIR must, at least at times, include coordination and integration of discrete interventions with wider programmatic efforts to address social and structural determinants of health.

Two recent advances in intervention research are highly relevant to LCIR. First, a recognition that intervention development, design, and refinement benefit from stakeholder involvement at every stage, providing both an end-user perspective for a codesign process and a greater understanding of the intervention context.¹⁸  Second, intervention development benefits from being broken down into distinct stages, each with substeps that provide a solid foundation for the next stage. Rushing through or omitting these steps in a “prototype to population” approach too often results in promising interventions failing to spread and scale. Each of these approaches is incorporated into the LCIRF(C). The Framework is divided into 5 stages (Fig 1), each of which merits further discussion below, with the 12 characteristics of life course interventions¹⁷  integrated into each stage.

A marked shift in the intervention development literature from an emphasis on professionally driven processes to collaboration between professionals and consumers based on human-centered design principles⁴⁵  necessitates forming new partnerships to conduct intervention research. Codesign goes beyond consultation or engagement of community members or intervention users, and instead acknowledges users as “experts of their own experiences” to improve design.^46,47  Collaborative stakeholders bring local knowledge into intervention design in ways that may better address issues of health equity and sustainability of change than traditional top-down approaches.⁴⁸  In child health, families of children with special health care needs are experts in that lived experience and valuable partners in intervention codesign.⁴⁹ 

All team members work together as equal partners bringing different perspectives on the prioritization of issues, mechanisms, and pathways underlying these issues and intervention strategies to address them.^50,51  Power and social relationships within teams need to be managed carefully so that all voices are heard, all options explored, and the process is productive.⁵²  Discovering the best ways to form intervention development teams, manage information exchange, and make decisions represents fertile new ground for research.

While graded literature reviews are a valuable resource, an over-reliance on the results of RCTs with statistically significant, yet clinically modest intervention impacts may have, paradoxically, limited progress and obscured subgroup effects.⁵³  A majority of intervention study subjects are White, non-Hispanic, resulting in uncertainty as to whether results are truly generalizable to Black, Asian and Hispanic populations.⁵⁴  Studies that demonstrate intervention impact, yet lack a causal explanation for the mechanism of action have limited value. In contrast, studies that focus on mediating variables that might be amenable to intervention, such as quality of parent-child interactions, are particularly valuable, being better aligned with the LCHD focus on emerging health development processes. Similarly, studies that address key moderators, such as family strengths and cultural values which tend to persist over time, yield valuable information to inform life course interventions.

Supplementing traditional literature reviews with “grey literature,” key informant interviews, and focus groups can enhance this knowledge synthesis. A transdisciplinary exchange of ideas can also give a more complete picture of potential targets for intervention and contextual understanding. E-surveys provide a route for input from a wide range of stakeholders within a short time frame.

This stage comprises design of the intervention and the study methodology, including the evaluation plan.

Codesign based on human-centered design principles results in interventions that lend themselves to end-user adaptations, facilitating spreading and scaling through diverse populations. Factors such as the intensity, frequency, and duration of interventions are important, being mindful that interventions with negative RCTs might have had a measured impact if the duration or frequency had been different. Similarly, the genesis and agent of an intervention matter, an intervention delivered in the context of an emotional relationship (eg, mother to child), may differ from 1 delivered by a health care worker. Third, the intervention location (home, clinic, or school) impacts meaning, acceptability, and feasibility. Fourth, timing impacts how well the intervention is aligned with sensitive periods, such as transitions and turning points. A checklist delineating the who, where, what, when, why, and how of the intervention will assist the team to document and report on each aspect and build a prototype.

A full consideration of intervention study designs is beyond the scope of this paper. Studies that test a conceptual model need to define the core elements of the model at this stage and the plan for testing it. A growing emphasis in LCIR on better understanding the processes and pathways that underlie emerging health development capabilities and trajectories of health is leading to a shift in study designs from outcome-oriented to process oriented. This has resulted in cautious support for the “intervention as research” approach of simply performing an intervention and closely monitoring its effects on a system^55,56  using pre and post designs or interrupted time series as a legitimate form of knowledge acquisition, even in the absence of an RCT. Understanding how an intervention impacts a biobehavioral process over time can give valuable information, both about the way the process unfolds and ways to intervene to improve or optimize that process.

More flexible, user-responsive study designs, eg, adaptive and SMART designs, tailored to individual needs have much to offer in individual health optimization efforts. Embedding interventions in longitudinal cohort studies has the advantage of a built-in long-term follow-up strategy, but the scope and focus may be constrained by the cohort study design. Studies with shorter periods of follow-up will still be valuable if they can study intervention impacts on emerging health development pathways, but longer-term effects would have to be inferred, risking significant over- or under-estimates.

Traditional evaluation approaches reliant largely on outcome measures work well when the outcome is clearly defined, eg, curing an illness, but are more challenging when the process or outcome occurs on a spectrum, or has features that are difficult to measure. Complex interventions with elements that address multiple ecosystem levels and aim for synergistic impacts require more complex evaluation plans,⁵⁷  and in LCIR, the study of processes may prove to be just as, if not more important, than outcomes. A focus on achieving optimal health requires new measures of thriving and flourishing, some of which will be determined by the community’s own definitions of these concepts. A suite of measures, including biological, physiologic, epigenetic, psychological, relational, and environmental, are needed. Mixed methods designs are becoming best practice, providing qualitative and quantitative data on both the study context and participant experiences. Stakeholder engagement in evaluation design supports acceptability and usability of evaluation measures, tools, and processes.

The design phase culminates in a pilot, which is usually a short-term, time-limited intervention closely monitored for intermediate, process-related effects. Evaluations must be short-term but thorough, incorporating mixed methods and actively searching for negative as well as positive intervention impacts. Much can be learned from unsuccessful interventions, especially from unanticipated negative effects. Ideally, this phase results in an intervention that is adaptable or customizable to different populations.

Traditionally the focus of funding, the implementation phase, refers to conducting the main study following a successful pilot. Much of the essential preparatory conceptual and design work must already be completed. Youth, family, and community representatives should remain engaged throughout, advising on adjustments needed to improve intervention implementation, and a community advisory board may be helpful in monitoring implementation. Additionally, a communications strategy should sustain community engagement and update stakeholders on progress. Flexible, responsive protocol adjustments represent good practice, as opposed to an over-reliance on protocol fidelity at the expense of effective implementation. This requires greater responsiveness of Institutional review boards. in reviewing requests for protocol adjustments, and greater openness of journals to transparent reporting.

In the evaluation stage, data collected during implementation, based on the evaluation plan, are analyzed and interpreted. Analysis strategies might test the validity of existing conceptual models, allowing for delineation of mediator and moderator effects and of path analysis. Relevant multilevel modeling and time-related analysis strategies may include structural equation modeling, factor analysis, path analysis, growth modeling, and latent class analysis. A full exploration of all the processes contributing to health trajectories over time creates analytic challenges, as many of these processes are nonlinear and incorporate dynamic 2-way interactions. Further research is needed into new methodologies that can address these more complex, “big data” types of analyses. Engaging stakeholders throughout the evaluation process, particularly in data interpretation, may help identify some of the less-apparent impacts (both positive and negative) and will support the next stage, translation.

Even with repeated demonstrations of effectiveness, a new intervention should be trialed and adjusted for varied populations and settings. Spreading an intervention throughout a population and translating it into everyday practice incorporates both implementation research and quality improvement approaches,^58,59  with RCTs seldom warranted or practical. Under-studied, under-reported and often not regarded as “real research,” this stage is very important if the intervention is to succeed. Understanding and reporting barriers to implementation prevents repeated mistakes across multiple intervention targets and modalities. From a life course perspective, failing to adopt or spread an effective intervention can have long-term effects on population health. At the conclusion of this stage, publishing lessons learned informs both basic and intervention development research, and the cycle of intervention development begins again.

Considering some of the differences between LCIR and more traditional intervention research highlights the challenges and opportunities of this new approach. First, the complex, multilayered nature of many life course interventions can make them conceptually challenging to design and resource-intensive to implement. They require more complex approaches to evaluation using higher-level statistical techniques and modeling strategies, often requiring specialized training. Determining which components of an intervention are key to its success is a real challenge with major implications for resource allocation. This type of research will require new methodologies and study approaches yet to be developed. A shift from RCTs to other study designs creates real risk of spurious associations, while limited resources for long-term follow-up studies risks over-reliance on inferred potential long-term impacts of interventions. At the same time, LCIR holds greater potential to change life-long trajectories compared with simpler time-limited approaches to intervention research. LCIR also offers a strategy for reaching health equity in a way that traditional intervention research does not by disrupting pathways and operating through bio-behavioral mechanisms influenced by social and structural determinants of health.

There are significant limitations to this approach to developing the LCIRF. First, we did not exhaustively review the many models and frameworks that have been applied to individual steps in intervention research, to single types of specialist interventions, or to interventions with special populations. Instead, we sought first to identify intervention frameworks or guidelines that were comprehensive in scope, addressing all of the steps in intervention research, of which the O’Cathain guidelines¹⁸  are most readily applicable to the types of complex, multilevel interventions envisaged by life course researchers. Second, this preliminary LCIR Framework has yet to undergo significant review and revisions by a diverse group of interdisciplinary life course researchers as well as stakeholder representatives. At present, it is the result of deliberations by a limited group of life course researchers. Third, it is not yet known if this framework will prove useful to researchers in the field. Strengths of the framework include its comprehensive description of steps for each stage of intervention design and development, the participation of family representatives in its development, and its incorporation of life course characteristics into all stages of the intervention development process.

The LCIRN has begun the process of building a Life Course Intervention Research Framework to assist researchers to adopt a more structured approach to theory testing, to describe with more rigor their life course intervention development process, and to communicate the study details transparently with coresearchers, community members, funders, and reviewers. The LCIRF is not meant to be exhaustive, but to serve as a starting or reference point for intervention researchers interested in addressing life course issues, and as a roadmap or checklist for professionals and communities, assisting them to collaborate on intervention research. Although still a work in progress, the LCIRF combines the best of intervention design principles with the characteristics of life course interventions to guide this evolving LCIR discipline.

LCHD

Life Course Health Development

LCIRF

Life Course Intervention Research Framework

LCIRN

Life Course Intervention Research Network

LCIR

life course intervention research

NCC

National Coordinating Center

RCT

randomized controlled trial

SMART

Sequential Multiple Assignment Randomized Trials