Making sense of the evidence in population health intervention research: building a dry stone wall

The association between precarious employment and stress among working aged individuals in the United States

OBJECTIVE

Precarious employment is a plausible stressor, which may adversely affect health. We investigated the association between multidimensional precarious employment and perceived and biological stress in the U.S.

METHODS

We used data from waves 4 (2008-2009) and 5 (2016-2018) of the National Longitudinal Study of Adolescent to Adult Health. Eight indicators were mapped to five dimensions of precarious employment to create a continuous score (PES, range: 0-5): material rewards, working-time arrangements, stability, workers' rights, and interpersonal relationships. Perceived stress was constructed from the four-item Cohen's perceived stress score (PSS; range: 0-16; wave 4). We measured biological stress in waves 4 and 5 via C-reactive protein (CRP). Given variability in CRP collection between waves, we treated wave 4 and 5 as cross-sectional. We employed adjusted linear regression models to estimate whether the PES was associated with the PSS in wave 4 (n = 11,510) and CRP in waves 4 (n = 10,343) and 5 (n = 3452).

RESULT

Individuals were aged 28 and 37 years on average in wave 4 and 5, respectively. Half were female and most identified as non-Hispanic (NH)-White (∼73 %), followed by NH-Black (∼14 %), Hispanic (∼9 %) and NH-other (∼4 %). Average PES was inversely related to education. The PSS averaged 8.1 (Interquartile Range [IQR] = 7.0,9.0). Average CRP was 4.4 mg/L (IQR = 0.8,5.0) in wave 4 and 3.6 mg/L (IQR = 0.8,4.2) in wave 5. The PES was associated with perceived stress (β=0.06; 95 % CI = 0.01,0.10) and CRP in wave 5 (β=0.34; 95 % CI = 0.07,0.62).

CONCLUSIONS

Given the deleterious effects of stress on health, policies to reduce precarious employment warrant consideration.

Uncovering the key working mechanisms of a complex community-based obesity prevention programme in the Netherlands using ripple effects mapping

BACKGROUND

Much remains unknown about how complex community-based programmes can successfully achieve long-term impact. More insight is needed to understand the key mechanisms through which these programmes work. Therefore, we conducted an in-depth study in five communities that implemented the Healthy Youth, Healthy Future (JOGG) approach, a Dutch community-based obesity prevention programme. We aimed to identify perceived outcomes and long-term impacts among local stakeholders and explore potential causal pathways and working mechanisms.

METHODS

We used ripple effects mapping (REM), a qualitative participatory method to map outcomes and identify causal pathways, in five communities. We involved 26 stakeholders, professionals and policy-makers affiliated with the local JOGG approach, spread over eight REM sessions and conducted individual interviews with 24 additional stakeholders. To uncover working mechanisms, we compared outcomes and causal pathways across communities.

RESULTS

Over 5-9 years of implementation, participants perceived that JOGG had improved ownership of local stakeholders, health policies, intersectoral collaboration and social norms towards promoting healthy lifestyles. Causal pathways comprised small initial outcomes that created the preconditions to enable the achievement of long-term impact. Although exact JOGG actions varied widely between communities, we identified five common working mechanisms through which the JOGG approach contributed to causal pathways: (1) creating a positive connotation with JOGG, (2) mobilizing stakeholders to participate in the JOGG approach, (3) facilitating projects to promote knowledge and awareness among stakeholders while creating successful experiences with promoting healthy lifestyles, (4) connecting stakeholders, thereby stimulating intersectoral collaboration and (5) sharing stakeholder successes that promote healthy lifestyles, which gradually created a social norm of participation.

CONCLUSIONS

The JOGG approach seems to work through activating initial stakeholder participation and bolstering the process towards ownership, policy change, and intersectoral collaboration to promote healthy lifestyles. Key working mechanisms can inform further development of JOGG as well as other complex community-based prevention programmes.

The tales of two cities: use of evidence for introducing 20 miles per hour speed limits in Edinburgh and Belfast (United Kingdom)

BACKGROUND

In 2016, large-scale 20 miles per hour speed limits were introduced in the United Kingdom cities of Edinburgh and Belfast. This paper investigates the role that scientific evidence played in the policy decisions to implement lower speed limits in the two cities.

METHODS

Using a qualitative case study design, we undertook content analysis of a range of documents to explore and describe the evolution of the two schemes and the ways in which evidence informed decision-making. In total, we identified 16 documents for Edinburgh, published between 2006 and 2016, and 19 documents for Belfast, published between 2002 and 2016.

FINDINGS

In both cities, evidence on speed, collisions and casualties was important for initiating discussions on large-scale 20 mph policies. However, the narrative shifted over time to the idea that 20 mph would contribute to a wider range of aspirations, none of which were firmly grounded in evidence, but may have helped to neutralize opposing discourses.

DISCUSSION AND CONCLUSIONS

The relationship between evidence and decision-making in Edinburgh and Belfast was neither simple nor linear. Widening of the narrative appears to have helped to frame the idea in such a way that it had broad acceptability, without which there would have been no implementation, and probably a lot more push back from vested interests and communities than there was.

Understanding how and why travel mode changes: analysis of longitudinal qualitative interviews

BACKGROUND

Encouraging alternatives to the car such as walking, cycling or public transport is a key cross-sector policy priority to promote population and planetary health. Individual travel choices are shaped by individual and environmental contexts, and changes in these contexts - triggered by key events - can translate to changes in travel mode. Understanding how and why these changes happen can help uncover more generalisable findings to inform future intervention research. This study aimed to identify the mechanisms and contexts facilitating changes in travel mode.

METHODS

Prospective longitudinal qualitative cohort study utilising semi-structured interviews at baseline (in 2021), three- and six-month follow up. Participants were residents in a new town in Cambridgeshire, UK, where design principles to promote walking, cycling and public transport were used at the planning stage. At each interview, we followed a topic guide asking participants about previous and current travel patterns and future intentions. All interviews were audio recorded and transcribed. Data analysis used the framework approach based on realist evaluation principles identifying the context and mechanisms described by participants as leading to travel behaviour change.

RESULTS

We conducted 42 interviews with 16 participants and identified six mechanisms for changes in travel mode. These entailed increasing or reducing access, reliability and financial cost, improving convenience, increasing confidence and raising awareness. Participants described that these led to changes in travel mode in contexts where their existing travel mode had been disrupted, particularly in terms of reducing access or reliability or increasing cost, and where there were suitable alternative travel modes for their journey. Experiences of the new travel mode played a role in future travel intentions.

IMPLICATIONS

Applying realist evaluation principles to identify common mechanisms for changes in travel mode has the potential to inform future intervention strategies. Future interventions using mechanisms that reduce access to, reduce reliability of, or increase the financial cost of car use may facilitate modal shift to walking, cycling and public transport when implemented in contexts where alternative travel modes are available and acceptable.

A complex systems lens can help us understand drivers of emerging challenges in work and health

Emergent health challenges related to work Work is not only central to population health but is also a significant driver of social inequality in health (1). In a recent Lancet series on work and health, the authors outlined six emergent challenges concerning work: the impact of technology, the intersection of work with sociodemographic health determinants, migrant work, precarious employment, long working hours, and climate change (1). The authors of the Lancet series also presented recommendations for future research, advocating for the utilization of mixed-methods, innovative analytical approaches (eg, causal modeling), realist evaluation, and interdisciplinary collaboration. Although each of these approaches are highly relevant, their integrated application was only vaguely outlined.

We believe that each of these work and health challenges show features of complex adaptive systems. They are multifaceted, constantly evolving, and emerge from our complex and disordered real world, which is often characterized by interactions, non-linearity, interference, feedback loops, and adaptation. Consequently, future research on work and health may benefit from adopting a complex systems perspective to obtain a comprehensive understanding of the drivers of these challenges (2–4). We have recently developed an interdisciplinary framework for knowledge production aimed at understanding complex health issues within the domain of public health, rooted in complex systems theory (5). This framework can serve to organize our thinking, formulate research questions, and integrate methodologies related to each of these six work and health challenges.

Briefly outlined, the Health Complexity framework relates to three core dimensions in which complex health issues may be conceptualized: patterns, mechanisms, and dynamics (5). Patterns: Looking for specific patterns of disease or risk factors allows us to empirically identify health issues that emerge from the mechanisms and dynamics of the underlying systems, eventually allowing us to discover vulnerable subgroups, and thereby set boundaries for targeted interventions. Mechanisms: Understanding the core mechanisms that give rise to these emergent health patterns and how they are connected across scales through interactions and interference can help us identify potential leverage points for intervention. Dynamics: Building evidence on the dynamics that make patterns and mechanisms change over time will allow us to identify vicious circles associated with particularly high morbidity.

Between them, these dimensions cover seven key features of complex systems (emergence, interactions, non-linearity, interference, feedback loops, adaptation, and evolution), which we have highlighted as central to public health. The Health Complexity framework builds upon the ideas of methodological pluralism (6–8) and is intended to be an overarching framework for interdisciplinary and collaborative research on complex health issues, also in the field of work and health. As an illustration, we will outline the elements needed to examine one of these challenges – precarious employment – through a complex systems lens, particularly highlighting how this approach influences the way we phrase research questions on health problems that do justice to the complexity of the real world.

Precarious employment viewed through a complex systems lens With globalization and technological advancements, there has been a shift towards a gig economy. This has led to an increase in temporary, part-time, and freelance work, which often lacks stability and benefits. Precarious employment specifically refers to such work characterized by employment insecurity, income inadequacy, and lack of rights and protection (9). The lack of stability and benefits associated with precarious employment combined with poor working conditions have been shown to have negative effects on physical and mental health (10–13). Workers may experience higher levels of stress, depression, and other health problems due to financial insecurity and lack of access to healthcare, which collectively may be an important driver of health inequality and of health decline. In a life course perspective, there may also be important feedback mechanisms exacerbating such inequality, with poor health not only being a consequence of precarious employment, but workers with poor health may be more likely to be excluded from stable work (14). Overall, the increasing prevalence of precarious employment represents a substantial challenge for public health, which can be seen as a sort of byproduct of larger societal trends. We believe that employing a complex systems lens can help us generate relevant scientific knowledge about the fundahttps://www.sjweh.fi/editoi.sjweh.fi/pics/update_u_3.gifmental drivers of this problem. This essentially entails three interlinked steps organized around the three core dimensions of the Health Complexity Framework (figure 1).

Patterns: As a first step, we need to zoom out and understand the health effects associated with emergent patterns of precarious employment in their context across time and space, asking questions such as: •How does precarious employment change over time, and how does this changing pattern affect population health? •Are there certain population groups, defined, eg, by socioeconomic status, age, occupation, migrant status, or geographical regions who experience more adverse health effects by precarious employment than others?

Systematically evaluating health patterns associated with precariousness can help us define boundaries for targeted prevention. Employing classical epidemiological surveillance methods alongside data science techniques for uncovering patterns within multidimensional large-scale datasets serves as key examples of such pattern identification.

Mechanisms: As a second step, we need to understand what mechanisms underlying the health effects of precariousness and how elements of these mechanisms are connected across scales, from cells to society, asking questions such as: •How do mechanisms interact across biological, behavioral, social, and societal scales to create the rising public health problems associated with precarious employment? •Does precarious employment and its associated health problems cluster and spread across social networks and/or across occupational and economic sectors?

Systematically evaluating the interconnectedness between mechanisms and individuals across various scales can help us identify leverage points for intervention. Whereas biomedical studies can contribute to uncovering the biological mechanisms linked to precarious employment, such as the embodiment of stress (15), the social sciences may offer profound insights into macro-scale mechanisms involving political, economic, and social structures.

Dynamics: As a third step, we need to explore how the health effects of precarious employment change over time due to dynamic processes like adaptation and feedback, asking questions such as: •How do national political and social contexts adapt to historical changes in the labor market including the increase in precarious employment, and what is the impact of this adaptation when it comes to how and to what extent precarious employment can affect the health of individuals and populations? •Is there a reinforcing feedback mechanism between social disadvantage, precarious employment, and health? This mechanism could create a vicious circle—for example, social disadvantage increasing the likelihood of precarious employment, which then leads to health consequences that may further reinforce social disadvantage.

Systematically assessing such dynamism can help us intervene on vicious circles that generate excessive burdens of disease in specific population groups. Systems methodology, including formal conceptual model building and computational simulations, are essential in creating such evidence.

Integrating interdisciplinary knowledge across these dimensions will provide a systematic and comprehensive understanding of the patterns of precarious employment and health, the underlying connected mechanisms generating these patterns, and the dynamics that makes them change over time. Some dimensions, like the patterns of precarious employment and health, may already be well-researched, while other dimensions such as dynamics require further investigation. We argue that it is essential to systematically explore all these dimensions to comprehensively understand a complex issue. Leaving out one of these core dimensions may leave blind spots that will render our understanding of precarious employment and health incomplete and thereby impact the efficiency of future interventions. In this editorial, we have focused on how to phrase research questions when applying a complex systems lens on precarious employment and health. This clearly needs to be matched by the integration of an interdisciplinary set of methods and data. An overview of such methods and data can be found in Rod et al (5).

Are we at the brink of a ‘complexity turn’ in public health? We believe that we are witnessing a shift in public health away from the traditional model of evidence, which primarily focused on empirically testing predefined hypotheses of single exposures and outcomes. Instead, there is a growing recognition of public health issues as complex, involving the complex interactions of biological, social, psychological, economic, and other processes across various levels and time scales (2–5, 16–20). These dynamics may show nonlinearity and adaptability. This paradigm shift is particularly important to our understanding of the relationship between work and health, including the emergent challenges outlined in the Lancet series, where contextual factors and interactions across micro-, meso- and macro-levels emerge as main drivers of dynamic change in employment condition. Formalizing this turn towards complexity in public health requires not only a realignment of our research questions as outlined for precarious employment above, but also necessitates the integration of traditional epidemiological methods with systems methodologies, such as computational simulation modeling (3, 18). Furthermore, it calls for sustained support for interdisciplinary collaboration and substantial investment in a diverse array of data types. These include multi-scale data, spatial data, time-series data, life-course data, network data, and multi-generational data, among others. This shift in our understanding of public health also impacts our approach to evidence synthesis. Traditionally, evidence synthesis has been relatively straightforward, typically summarized in systematic reviews or meta-analyses focusing on single isolated risk factors. However, with a complex systems perspective, we must transition towards a dynamic evidence synthesis framework. This approach involves an ongoing process of data-driven discoveries, hypothesis testing, and theory building. By adopting this dynamic approach, we can effectively synthesize evidence on complex research questions while continuously assessing which dimensions remain unresolved and understudied. These unresolved or understudied aspects should serve as guiding principles for future studies and research programs, also on work and health.

Funding NHR acknowledge funding from the European Union (ERC, LAYERS, project no. 101124807). The views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.

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Hypothetical mechanisms driving physical activity levels in ethnic minority groups living in Europe: a systematically identified evidence-based conceptual systems model

BACKGROUND

In Europe, physical activity levels tend to be lower in ethnic minority groups than the general population. Interventions and policies based on research examining isolated determinants of physical activity have had limited success in increasing physical activity levels. This study used systems dynamics theory and the capability approach theoretical framework to develop a conceptual model of how individual characteristics, institutional and physical environments and the migration context may interact to promote or hinder physical activity in ethnic minority groups living in Europe.

METHODS

A systematic update of Langøien et al.'s 2017 review of the determinants of physical activity in ethnic minority groups living in Europe was conducted. Our target population included individuals of all ages who reported a familial migration background from any low- and middle-income countries or belonging to minority indigenous population in Europe. Outcomes pertaining to non-work related physical activity of light, moderate or vigorous intensity performed in any setting were included. Included studies provided an evidence base from which to derive the causal loop diagrams comprising our conceptual model. Sub-system causal loop diagrams were interpreted in co-author review sessions to explicate non-linear system mechanisms, such as reinforcing and balancing feedback loops.

RESULTS

Forty-one studies were identified, of which the majority was qualitative. The conceptual model consisted of 4 causal loop diagrams relating to psychosocial constructs; sociocultural constructs; health and health communication and social and material resources, in interaction with environmental/migration context. Four hypothetical mechanisms were identified, e.g. hypothesizing that participation in organised activities leads to increased self-efficacy, thereby enabling further participation.

CONCLUSIONS

This study contributes an evidence-based conceptual systems model which elucidates how low levels of physical activity in ethnic minority groups in Europe could be supported by reinforcing and balancing mechanisms involving factors relating to physical and institutional environments, migration context and individuals. A pluralistic approach to literature review, integrating complexity methods such as CLDs into more conventional systematic literature review, supports novel insights into how factors could interact to support persistently low levels of activity, moving beyond the identification of potential relationships between isolated factors to indicating the ways in which these relationships are sustained and could be modified by intervention or policy.

Population-level interventions for the primary prevention of dementia: a complex evidence review

Dementia risk reduction is a global public health priority. Existing primary prevention approaches have favored individual-level interventions, with a research and policy gap for population-level interventions. We conducted a complex, multi-stage, evidence review to identify empirical evidence on population-level interventions for each of the modifiable risk factors identified by the Lancet Commission on dementia (2020). Through a comprehensive series of targeted searches, we identified 4604 articles, of which 135 met our inclusion criteria. We synthesized evidence from multiple sources, including existing non-communicable disease prevention frameworks, and graded the consistency and comprehensiveness of evidence. We derived a population-level intervention framework for dementia risk reduction, containing 26 high- and moderate-confidence policy recommendations, supported by relevant information on effect sizes, sources of evidence, contextual information, and implementation guidance. This review provides policymakers with the evidence they need, in a useable format, to address this critical public health policy gap.

Funding

SW is funded by a National Institute for Health and Care Research (NIHR) Doctoral Fellowship. WW and LF are part funded by the NIHR Applied Research Collaboration East of England. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.

Changing mobility practices. Can meta-ethnography inform transferable and policy-relevant theory?

Social practice theories have attracted attention for their potential insights into how to change transport systems towards "healthier" states. However, most evidence is from small-scale qualitative case studies. We explored whether a synthesis of qualitative evidence on mobility practices in one country, informed by meta-ethnography and a Bourdieusian approach to practice, could produce theory that is of sufficient abstraction to be transferable, yet also capable of informing intervention planning. The synthesis identified three third order constructs: mobility practices result from habitus plus capital in fields; specific configurations of local mobility practices are shaped, but not determined, by material infrastructures and social structures; and changes in practice happen across a number of scales and temporalities. This body of evidence as a whole was then interpreted as an integrative "storyline": Mobility systems are complex, in that outcomes from interventions are neither unilinear nor necessarily predictable from aggregations of individual practice changes. Infrastructure changes may be a necessary, but not sufficient, condition for change. Moving systems towards "healthier" states requires changing habitus such that "healthier" practices align with fields, and that interventions take sufficient account of the power relations that materially and symbolically constrain or enable attachments to and changes in mobility practices. Meta-ethnography is a useful approach for integrating qualitative evidence for informing policy.

Complexity in Epidemiology and Public Health. Addressing Complex Health Problems Through a Mix of Epidemiologic Methods and Data

Public health and the underlying disease processes are complex, often involving the interaction of biologic, social, psychologic, economic, and other processes that may be nonlinear and adaptive and have other features of complex systems. There is therefore a need to push the boundaries of public health beyond single-factor data analysis and expand the capacity of research methodology to tackle real-world complexities. This article sets out a way to operationalize complex systems thinking in public health, with a particular focus on how epidemiologic methods and data can contribute towards this end. Our proposed framework comprises three core dimensions-patterns, mechanisms, and dynamics-along which complex systems may be conceptualized. These dimensions cover seven key features of complex systems-emergence, interactions, nonlinearity, interference, feedback loops, adaptation, and evolution. We relate this framework to examples of methods and data traditionally used in epidemiology. We conclude that systematic production of knowledge on complex health issues may benefit from: formulation of research questions and programs in terms of the core dimensions we identify, as a comprehensive way to capture crucial features of complex systems; integration of traditional epidemiologic methods with systems methodology such as computational simulation modeling; interdisciplinary work; and continued investment in a wide range of data types. We believe that the proposed framework can support the systematic production of knowledge on complex health problems, with the use of epidemiology and other disciplines. This will help us understand emergent health phenomena, identify vulnerable population groups, and detect leverage points for promoting public health.

Understanding how to create healthier places: A qualitative study exploring the complex system of urban development decision-making

Tackling complex system challenges like creating healthy environments requires understanding priorities and structures affecting multiple actors. This qualitative study, involving 132 multi-sectoral stakeholders spanning the urban development decision-making system, explores how to influence healthier place-making. Using thematic analysis we develop themes around competing stakeholder priorities; structural 'rules' and influential relationships; and justifying a focus on health, requiring greater clarity and consensus around definitions of 'healthy' urban development. Building on the socio-ecological model we highlight how a multi-faceted approach is required for change at multiple levels in the complex system to target individual actor motivations, organisational priorities and structural 'rules'.

The impact of economic sanctions on health and health systems in low-income and middle-income countries: a systematic review and narrative synthesis

INTRODUCTION

Economic sanctions restrict customary commercial and financial ties between states to induce change in political constitution or conduct of the targeted country. Although the stated goals of sanctions often include humanitarian objectives, prospective procedures for health risk assessment are not regularly incorporated in their implementation. Moreover, past experience suggests that the burden of economic isolation may fall on the civilian population. We present key findings from a WHO-sponsored evidence review on the impact of economic sanctions on health and health systems in low-income and middle-income countries, aiming at comprehensive coverage and explicit consideration of issues of causality and mechanisms.

METHODS

Broad searches of PubMed and Google Scholar (1970-2021) were designed to retrieve published and grey English-language literature expected to cut across disciplines, terminology and research methods. Studies providing an impact estimate were rated by a structured assessment based on ROBINS-I risk of bias domains, synthesised via vote counting and contextualised into the broader literature through a thematic synthesis.

RESULTS

Included studies (185) were mostly peer-reviewed, mostly single-country, largely coming from medicine and public health, and chiefly concerned with three important target countries-Iraq, Haiti and Iran. Among studies providing impact estimates (31), most raised multiple risk-of-bias concerns. Excluding those with data integrity issues, a significant proportion (21/27) reported consistently adverse effects of sanctions across examined outcomes, with no apparent association to assessed quality, focus on early episodes or publication period. The thematic synthesis highlights the complexity of sanctions, their multidimensionality and the possible mechanisms of impact.

CONCLUSION

Future research should draw on qualitative knowledge to collect domain-relevant data, combining it with better estimation techniques and study design. However, only the adoption of a risk assessment framework based on prospective data collection and monitoring can certify claims that civilians are adequately protected.

Active travel and paratransit use in African cities: Mixed-method systematic review and meta-ethnography

Active travel, as a key form of physical activity, can help offset noncommunicable diseases as rapidly urbanising countries undergo epidemiological transition. In Africa a human mobility transition is underway as cities sprawl and motorization rises and preserving active travel modes (walking, cycling and public transport) is important for public health. Across the continent, public transport is dominated by paratransit, privately owned informal modes serving the general public. We reviewed the literature on active travel and paratransit in African cities, published from January 2008 to January 2019. We included 19 quantitative, 14 mixed-method and 8 qualitative studies (n = 41), narratively synthesizing the quantitative data and meta-ethnographically analysing the qualitative data. Integrated findings showed that walking was high, cycling was low and paratransit was a critical mobility option for poor peripheral residents facing long livelihood-generation journeys. As an indigenous solution to dysfunctional mobility systems shaped by colonial and apartheid legacies it was an effective connector, penetrating areas unserved by formal public transport and helping break cycles of poverty. From a public health perspective, it preserved active travel by reducing mode-shifting to private vehicles. Yet many city authorities viewed it as rogue, out of keeping with the 'ideal modern city', adopting official anti-paratransit stances without necessarily considering the contribution of active travel to public health. The studies varied in quality and showed uneven geographic representation, with data from Central and Northern Africa especially sparse; notably, there was a high prevalence of non-local authors and out-of-country funding. Nevertheless, drawing together a rich cross-disciplinary set of studies spanning over a decade, the review expands the literature at the intersection of transport and health with its novel focus on paratransit as a key active travel mode in African cities. Further innovative research could improve paratransit's legibility for policymakers and practitioners, fostering its inclusion in integrated transport plans.

Case study research and causal inference

Case study methodology is widely used in health research, but has had a marginal role in evaluative studies, given it is often assumed that case studies offer little for making causal inferences. We undertook a narrative review of examples of case study research from public health and health services evaluations, with a focus on interventions addressing health inequalities. We identified five types of contribution these case studies made to evidence for causal relationships. These contributions relate to: (1) evidence about system actors' own theories of causality; (2) demonstrative examples of causal relationships; (3) evidence about causal mechanisms; (4) evidence about the conditions under which causal mechanisms operate; and (5) inference about causality in complex systems. Case studies can and do contribute to understanding causal relationships. More transparency in the reporting of case studies would enhance their discoverability, and aid the development of a robust and pluralistic evidence base for public health and health services interventions. To strengthen the contribution that case studies make to that evidence base, researchers could: draw on wider methods from the political and social sciences, in particular on methods for robust analysis; carefully consider what population their case is a case 'of'; and explicate the rationale used for making causal inferences.

ASPHALT II: Study Protocol for a Multi-Method Evaluation of a Comprehensive Peer-Led Youth Community Sport Programme Implemented in Low Resource Neighbourhoods

To reduce inequalities in children's sport participation, studies are needed to explore ways in which children from low resource neighbourhoods can be engaged and retained in sport. GAME Community is a peer-led community sport programme which aims to promote physical activity through participation in inclusive street sports activities targeting 8-15-year-old children living in low resource neighbourhoods. The GAME Community intervention is implemented by the non-profit street sport organisation GAME. Five components support the implementation of GAME Community: (1) training of peer leaders; (2) a focus on inclusion of inactive girls; (3) parental involvement; (4) community engagement; (5) strengthened organisational support to peer leaders. In the ASPHALT II study, we aim to evaluate GAME Community and hence contribute to understanding how children growing up in low resource neighbourhoods can be engaged and retained in physical activity through participation in peer-led, community-based sport and to generate new understandings on the scale up of community interventions. The primary objective of the evaluation is to investigate the implementation of GAME Community and the programme's reach, and to establish the functioning and mechanisms of the programme. The secondary objective is to establish the health enhancing potential of the programme. The evaluation of GAME Community involves three linked but independent studies that investigate (1) the functioning (i.e., mechanisms and processes), (2) reach, and (3) outcomes. The functioning of the five intervention components is investigated using qualitative methodologies. Programme reach will be investigated based on participant registrations. Systematic observations using a novel combination of validated tools will provide information on outcomes (physical activity level and social behaviour) during GAME Community activities. Investigating functioning, reach, and outcomes of the GAME Community intervention by using multiple methods is a strength, as different data complement and inform each other. This study will provide in-depth insights into if and how children living in low resource neighbourhoods can be engaged and retained in physical activity through participation in peer-led, community-based sport. Contributions of this evaluation include new understanding of the mechanisms and scalability of a community-based street sport intervention.

Evidence in public health: An integrated, multidisciplinary concept

AIMS

Traditionally, evidence in public health has been founded in health sciences using the hierarchy of evidence. In this Commentary, we argue that we need a combination of evidence based on a broad range of scientific disciplines and methodologies to best translate research into improved public health.

METHODS

Using existing concepts of evidence such as the hierarchy of evidence and the evidence typology, we discuss their pitfalls in public health science and suggest a way forward. We use the case of the MAMAACT intervention to exemplify our claims.

RESULTS

Public health does not apply an either/or perspective, but an integrated, theoretically informed approach based on mixed and multiple methods to understand complex health problems and how to tackle them. Ideally, public health decisions should always incorporate scientific evidence, although we need to fully acknowledge that the quality of evidence is defined by more than just being placed highest in the hierarchy of evidence. No method or study design is superior in obtaining evidence, but we need the combined and supplemented contributions from a range of scientific approaches to form a whole. Thus, we propose an integrated, multidisciplinary concept of evidence in the form of cogwheels, where the public health problem followed by the research question(s) will guide the components to be studied and the use of method(s) in an interplay with the decisions of the scientific perspective(s) that include choice of theories.

CONCLUSIONS

We cannot understand or solve public health challenges without multidisciplinary approaches in a complimentary formation.

Shifting towards healthier transport: carrots or sticks? Systematic review and meta-analysis of population-level interventions

BACKGROUND

Promoting active travel can be beneficial for both health and the environment. However, evidence about the most effective strategies is inconsistent. We aimed to compare the effectiveness of interventions with positive (ie, carrot), negative (ie, stick), or a combination of strategies on changing population-level travel behaviour. We also aimed to identify which intervention functions, or mechanisms of how interventions seek to alter behaviour (eg, by addressing safety or accessibility), affect transport outcomes.

METHODS

For this systematic review and meta-analysis, we searched eight online databases for studies published before March 28, 2022: Web of Science, MEDLINE, Scopus, Applied Social Sciences Index and Abstracts, Global Health, PsycINFO, CINAHL, and Transport Research International Documentation. We did not restrict searches by language or publication date. We included controlled before-and-after studies of population-level interventions and travel behaviours (ie, driving, public transport, walking, and cycling) from adults in the general population. We categorised interventions according to their function. Depending on whether gains or losses due to intervention function could occur, we classified interventions as carrot (eg, new bike-share programmes), stick (eg, congestion charging), or combined carrot-and-stick interventions (eg, pedestrianising areas by use of reallocated parking space). We used harvest plots to summarise the findings and guide narrative synthesis. Where possible, we converted outcomes into standardised mean differences and did random-effects meta-analyses.

FINDINGS

From 38 916 records screened, 102 reports describing 121 interventions met the inclusion criteria. 79 interventions were carrots, 22 were carrot-and-sticks, and 20 were sticks. Results for carrot interventions were less consistent than for stick or combined interventions. Findings from the meta-analysis (64 reports describing 67 interventions) agreed with those in the narrative synthesis; although effects were statistically non-significant, for driving outcomes, interventions with stick strategies (standardised mean difference [SMD] -0·17, 95% CI -0·36 to 0·02) and combined carrot-and-stick strategies (-0·13, -0·47 to 0·20) had point estimates of greater magnitude than those for interventions with carrot strategies (-0·10, -0·23 to 0·03). Likewise, for active travel outcomes, combined carrot-and-stick strategies had a higher point estimate (0·33, -0·01 to 0·68) compared with carrot interventions (0·08, -0·05 to 0·21). Functions thought to change behaviour using financial means were effective at decreasing driving behaviour, whereas those improving access, safety, and space were effective for increasing active travel outcomes.

INTERPRETATION

This Article found that, although transport interventions with only positive strategies are more commonly evaluated, interventions that combine both positive and negative strategies might be more effective at encouraging alternatives to driving at the population level. Further research is needed for interventions involving a stick strategy, which remain less widely implemented or well studied than those with only carrot strategies.

FUNDING

Medical Research Council, Cambridge Trust.

Features of effective staff training programmes within school-based interventions targeting student activity behaviour: a systematic review and meta-analysis

BACKGROUND

Evaluations of school-based activity behaviour interventions suggest limited effectiveness on students' device-measured outcomes. Teacher-led implementation is common but the training provided is poorly understood and may affect implementation and student outcomes. We systematically reviewed staff training delivered within interventions and explored if specific features are associated with intervention fidelity and student activity behaviour outcomes.

METHODS

We searched seven databases (January 2015-May 2020) for randomised controlled trials of teacher-led school-based activity behaviour interventions reporting on teacher fidelity and/or students' device-measured activity behaviour. Pilot, feasibility and small-scale trials were excluded. Study authors were contacted if staff training was not described using all items from the Template for Intervention Description and Replication reporting guideline. Training programmes were coded using the Behaviour Change Technique (BCT) Taxonomy v1. The Effective Public Health Practice Project tool was used for quality assessment. Promise ratios were used to explore associations between BCTs and fidelity outcomes (e.g. % of intended sessions delivered). Differences between fidelity outcomes and other training features were explored using chi-square and Wilcoxon rank-sum tests. Random-effects meta-regressions were performed to explore associations between training features and changes in students' activity behaviour.

RESULTS

We identified 68 articles reporting on 53 eligible training programmes and found evidence that 37 unique teacher-targeted BCTs have been used (mean per programme = 5.1 BCTs; standard deviation = 3.2). The only frequently identified BCTs were 'Instruction on how to perform the behaviour' (identified in 98.1% of programmes) and 'Social support (unspecified)' (50.9%). We found moderate/high fidelity studies were significantly more likely to include shorter (≤6 months) and theory-informed programmes than low fidelity studies, and 19 BCTs were independently associated with moderate/high fidelity outcomes. Programmes that used more BCTs (estimated increase per additional BCT, d: 0.18; 95% CI: 0.05, 0.31) and BCTs 'Action planning' (1.40; 0.70, 2.10) and 'Feedback on the behaviour' (1.19; 0.36, 2.02) were independently associated with positive physical activity outcomes (N = 15). No training features associated with sedentary behaviour were identified (N = 11).

CONCLUSIONS

Few evidence-based BCTs have been used to promote sustained behaviour change amongst teachers in school-based activity behaviour interventions. Our findings provide insights into why interventions may be failing to effect student outcomes.

TRIAL REGISTRATION

PROSPERO registration number: CRD42020180624.

Using systems science methods to enhance the work of national and local walking partnerships: practical insights from Ireland

Background

Physical activity (PA) literature is dominated by individual-level descriptive studies, which are known to have limited impact on population PA levels. Leveraging systems science methods offers opportunities to approach PA in a manner which embraces its inherent complexity. This study describes how participatory systems mapping and social network analysis (SNA) were used to understand the work of local and national level walking systems in Ireland.

Methods

Two adapted participatory action research workshops with multisectoral stakeholders were used to develop a systems map for walking in Cork, Ireland. The Global Action Plan for Physical Activity 2018–2030 (GAPPA) map was used as a framework to categorize workshop outcomes. Secondly, SNA methods were used to analyse the communication network between partners of Get Ireland Walking, a national walking promotion initiative, as defined within their strategic plan and the actual communication network as experienced by the partners.

Results

The systems mapping process allowed stakeholders to identify 19 suggested actions for the Cork walking system. The SNA found that there were considerably fewer communication ties between partners in the actual communication network than in the strategy defined network.

Conclusion

The systems mapping process was a useful catalyst for engaging stakeholders in cross-sectoral communication and the GAPPA was a practical way to organize workshop outcomes. Social network analysis methods highlighted that the communication network of a national level walking promotion partnership is not working as planned. Overall, the use of systems science methods can provide practical insights for local and national level walking systems.

Adapt or die: how the pandemic made the shift from EBM to EBM+ more urgent

Evidence-based medicine (EBM's) traditional methods, especially randomised controlled trials (RCTs) and meta-analyses, along with risk-of-bias tools and checklists, have contributed significantly to the science of COVID-19. But these methods and tools were designed primarily to answer simple, focused questions in a stable context where yesterday's research can be mapped more or less unproblematically onto today's clinical and policy questions. They have significant limitations when extended to complex questions about a novel pathogen causing chaos across multiple sectors in a fast-changing global context. Non-pharmaceutical interventions which combine material artefacts, human behaviour, organisational directives, occupational health and safety, and the built environment are a case in point: EBM's experimental, intervention-focused, checklist-driven, effect-size-oriented and deductive approach has sometimes confused rather than informed debate. While RCTs are important, exclusion of other study designs and evidence sources has been particularly problematic in a context where rapid decision making is needed in order to save lives and protect health. It is time to bring in a wider range of evidence and a more pluralist approach to defining what counts as 'high-quality' evidence. We introduce some conceptual tools and quality frameworks from various fields involving what is known as mechanistic research, including complexity science, engineering and the social sciences. We propose that the tools and frameworks of mechanistic evidence, sometimes known as 'EBM+' when combined with traditional EBM, might be used to develop and evaluate the interdisciplinary evidence base needed to take us out of this protracted pandemic. Further articles in this series will apply pluralistic methods to specific research questions.

Socioeconomic and gendered inequities in travel behaviour in Africa: Mixed-method systematic review and meta-ethnography

Travel has individual, societal and planetary health implications. We explored socioeconomic and gendered differences in travel behaviour in Africa, to develop an understanding of travel-related inequity. We conducted a mixed-methods systematic review (PROSPERO CRD42019124802). In 2019, we searched MEDLINE, TRID, SCOPUS, Web of Science, LILACS, SciELO, Global Health, Africa Index Medicus, CINAHL and MediCarib for studies examining travel behaviour by socioeconomic status and gender in Africa. We appraised study quality using Critical Appraisal Skills Programme checklists. We synthesised qualitative data using meta-ethnography, followed by a narrative synthesis of quantitative data, and integrated qualitative and quantitative strands using pattern matching principles. We retrieved 103 studies (20 qualitative, 24 mixed-methods, 59 quantitative). From the meta-ethnography, we observed that travel is: intertwined with social mobility; necessary to access resources; associated with cost and safety barriers; typified by long distances and slow modes; and dictated by gendered social expectations. We also observed that: motorised transport is needed in cities; walking is an unsafe, 'captive' mode; and urban and transport planning are uncoordinated. From these observations, we derived hypothesised patterns that were tested using the quantitative data, and found support for these overall. In lower socioeconomic individuals, travel inequity entailed reliance on walking and paratransit (informal public transport), being unable to afford travel, travelling less overall, and travelling long distances in hazardous conditions. In women and girls, travel inequity entailed reliance on walking and lack of access to private vehicles, risk of personal violence, societally-imposed travel constraints, and household duties shaping travel. Limitations included lack of analytical rigour in qualitative studies and a preponderance of cross-sectional quantitative studies (offering a static view of an evolving process). Overall, we found that travel inequity in Africa perpetuates socioeconomic and gendered disadvantage. Proposed solutions focus on improving the safety, efficiency and affordability of public transport and walking.

Miasmas, mental models and preventive public health: some philosophical reflections on science in the COVID-19 pandemic

When the history of the COVID-19 pandemic is written, it is likely to show that the mental models held by scientists sometimes facilitated their thinking, thereby leading to lives saved, and at other times constrained their thinking, thereby leading to lives lost. This paper explores some competing mental models of how infectious diseases spread and shows how these models influenced the scientific process and the kinds of facts that were generated, legitimized and used to support policy. A central theme in the paper is the relative weight given by dominant scientific voices to probabilistic arguments based on experimental measurements versus mechanistic arguments based on theory. Two examples are explored: the cholera epidemic in nineteenth century London-in which the story of John Snow and the Broad Street pump is retold-and the unfolding of the COVID-19 pandemic in 2020 and early 2021-in which the evidence-based medicine movement and its hierarchy of evidence features prominently. In each case, it is shown that prevailing mental models-which were assumed by some to transcend theory but were actually heavily theory-laden-powerfully shaped both science and policy, with fatal consequences for some.

Trends in recreational walking trail usage in Ireland during the COVID-19 pandemic: Implications for practice

Despite its potential utility for the outdoor recreation sector, there is no centralised surveillance system for recreational walking trails in Ireland and thus trail usage in Ireland during the COVID-19 pandemic is unknown. This paper aims to report trends in footfall count data on Irish trails during the COVID-19 period and to triangulate findings with openly available mobility data. This descriptive study analysed changes in footfall counts gathered from passive infrared sensors on 33 of Ireland’s recreational walking trails between January 2019 and December 2020. The relationship between Google Community Mobility Report (GCMR) data and footfall counts was analysed to corroborate trends in footfall data. Total footfall increased by 6% between 2019 and 2020 on trails included in this analysis. Notably, mean trail usage was between 26% and 47% higher in October–December 2020 than during the same period in 2019. A strong correlation between GCMR data from ‘parks’ and footfall count data was found. The conclusions of this study are twofold. Firstly, the COVID-19 pandemic increased trail usage in Ireland, especially on trails closer to urban areas and there is potential for this to be a lasting legacy. Secondly, combining multiple data sources can provide trail managers with more detailed representations of trail usage and currently these are not harmonised. Future research should examine ways to encourage sustained recreational walking trail use in new users and implement novel ways to coordinate datasets across systems to monitor visitors on Irish recreational walking trails.

Management implications

This paper presents a number of implications for trail management teams to consider:•

Openly available datasets pertaining to mobility, such as Google Community Mobility Reports, can be utilised to corroborate data collected from footfall sensors in place on trails. Furthermore, there may be potential for Google Trends data to help trail management teams gauge interest in specific trails and parks during defined time frames.

•

There is considerable potential to sustain the COVID-19 legacy of increased trail use, especially for trails closer to urban areas, through promotional campaigns and continued trail maintenance.

•

There is a need to work across sectors and disciplines within the recreational walking system to identify potential data sources and opportunities for further data collection.

Following the science? Views from scientists on government advisory boards during the COVID-19 pandemic: a qualitative interview study in five European countries

INTRODUCTION

In order to tackle the pandemic, governments have established various types of advisory boards to provide evidence and recommendations to policy makers. Scientists working on these boards have faced many challenges, including working under significant time constraints to produce 'evidence' as quickly as possible. However, their voices are still largely missing in the discussion. This study explores the views and experiences of scientists working on government advisory boards during the COVID-19 pandemic, with the aim to learn lessons for future pandemic management and preparedness.

METHODS

We conducted online video or telephone semi-structured interviews between December 2020 and April 2021 with 21 scientists with an official government advisory role during the COVID-19 pandemic in Belgium, the Netherlands, UK, Sweden and Germany. The interviews were audio-recorded and transcribed and analysed using a combination of inductive and deductive thematic analysis techniques.

RESULTS

Scientists viewed the initial focus on biomedically oriented work during the pandemic as somewhat one-dimensional, but also highlighted difficulties of working in an interdisciplinary way. They found it difficult at times to ensure that the evidence is understood and taken on board by governments. They found themselves taking on new roles, the boundaries of which were not clearly defined. Consequently, they were often perceived and treated as a public figure.

CONCLUSION

Scientists working on advisory boards in European countries faced similar challenges, highlighting key lessons to be learnt. Future pandemic preparedness efforts should focus on building interdisciplinary collaboration through development of scientists' skills and appropriate infrastructure; ensuring transparency in how boards operate; defining and protecting the boundaries of the scientific advisor role; and supporting scientists to inform the public in the fight against disinformation, while dealing with potential hostile reactions.