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.

The use of Qualitative Comparative Analysis (QCA) to address causality in complex systems: a systematic review of research on public health interventions.

BACKGROUND: Qualitative Comparative Analysis (QCA) is a method for identifying the configurations of conditions that lead to specific outcomes. Given its potential for providing evidence of causality in complex systems, QCA is increasingly used in evaluative research to examine the uptake or impacts of public health interventions. We map this emerging field, assessing the strengths and weaknesses of QCA approaches identified in published studies, and identify implications for future research and reporting. METHODS: PubMed, Scopus and Web of Science were systematically searched for peer-reviewed studies published in English up to December 2019 that had used QCA methods to identify the conditions associated with the uptake and/or effectiveness of interventions for public health. Data relating to the interventions studied (settings/level of intervention/populations), methods (type of QCA, case level, source of data, other methods used) and reported strengths and weaknesses of QCA were extracted and synthesised narratively. RESULTS: The search identified 1384 papers, of which 27 (describing 26 studies) met the inclusion criteria. Interventions evaluated ranged across: nutrition/obesity (n = 8); physical activity (n = 4); health inequalities (n = 3); mental health (n = 2); community engagement (n = 3); chronic condition management (n = 3); vaccine adoption or implementation (n = 2); programme implementation (n = 3); breastfeeding (n = 2), and general population health (n = 1). The majority of studies (n = 24) were of interventions solely or predominantly in high income countries. Key strengths reported were that QCA provides a method for addressing causal complexity; and that it provides a systematic approach for understanding the mechanisms at work in implementation across contexts. Weaknesses reported related to data availability limitations, especially on ineffective interventions. The majority of papers demonstrated good knowledge of cases, and justification of case selection, but other criteria of methodological quality were less comprehensively met. CONCLUSION: QCA is a promising approach for addressing the role of context in complex interventions, and for identifying causal configurations of conditions that predict implementation and/or outcomes when there is sufficiently detailed understanding of a series of comparable cases. As the use of QCA in evaluative health research increases, there may be a need to develop advice for public health researchers and journals on minimum criteria for quality and reporting.

Study protocol for evaluation of aid to diagnosis for developmental dysplasia of the hip in general practice: controlled trial randomised by practice.

INTRODUCTION: In the UK, a compulsory '6-week hip check' is performed in primary care for the detection of developmental dysplasia of the hip (DDH). However, missed diagnoses and infants incorrectly labelled with DDH remain a problem, potentially leading to adverse consequences for infants, their families and the National Health Service. National policy states that infants should be referred to hospital if the 6-week check suggests DDH, though there is no available tool to aid examination or offer guidelines for referral. We developed standardised diagnostic criteria for DDH, based on international Delphi consensus, and a 9-item checklist that has the potential to enable non-experts to diagnose DDH in a manner approaching that of experts. METHODS AND ANALYSIS: We will conduct a controlled trial randomised by practice that will compare a diagnostic aid against standard care for the hip check. The primary objective is to determine whether an aid to the diagnosis of DDH reduces the number of clinically insignificant referrals from primary care to hospital and the number of late diagnosed DDH. The trial will include a qualitative process evaluation, an assessment of professional behavioural change and a full health economic evaluation. We will recruit 152 general practitioner practices in England. These will be randomised to conduct the hip checks with use of the study diagnostic aid and/or as per usual practice. The total number of infants seen during a 15-month recruitment period will be 110 per practice. Two years after the 6-week hip check, we will measure the number of referred infants that are (1) clinically insignificant for DDH and (2) those that constitute appropriate referrals. ETHICS AND DISSEMINATION: This study has approval from the Health Research Authority (16/1/2020) and the Confidentiality Advisory Group (18/2/2020). Results will be published in peer-reviewed academic journals, disseminated to patient organisations and the media. TRIAL REGISTRATION NUMBER: NCT04101903; Pre-results.

Protocol for a systematic review of the use of qualitative comparative analysis for evaluative questions in public health research.

BACKGROUND: There is an increasing recognition that health intervention research requires methods and approaches that can engage with the complexity of systems, interventions, and the relations between systems and interventions. One approach which shows promise to this end is qualitative comparative analysis (QCA), which examines casual complexity across a medium to large number of cases (between 10 and 60+), whilst also being able to generalise across those cases. Increasingly, QCA is being adopted in public health intervention research. However, there is a limited understanding of how it is being adopted. This systematic review will address this gap, examining how it is being used to understand complex causation; for what settings, populations and interventions; and with which datasets to describe cases. METHODS: We will include published and peer-reviewed studies of any public health intervention where the effects on population health, health equity, or intervention uptake are being evaluated. Electronic searches of PubMed, Scopus, Web of Science (incorporating Social Sciences Citation Index and Arts & Humanities Citation Index), Microsoft Academic, and Google Scholar will be performed. This will be supplemented with reference citation tracking and personal contact with experts to identify any additional published studies. Search results will be single screened, with machine learning used to check these results, acting as a 'second screener'. Any disagreement will be resolved through discussion. Data will be extracted from full texts of eligible studies, which will be assessed against inclusion criteria, and synthesised narratively, using thematic synthesis methods. DISCUSSION: This systematic review will provide an important map of the increasing use of QCA in public health intervention literature. This review will identify the current scope of research in this area, as well as assessing claims about the utility of the method for addressing complex causation in public health research. We will identify implications for better reporting of QCA methods in public health research and for reporting of case studies such that they can be used in future QCA studies. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD42019131910.

The Daily Mile as a public health intervention: a rapid ethnographic assessment of uptake and implementation in South London, UK.

BACKGROUND: Existing evidence identifies health benefits for children of additional daily physical activity (PA) on a range of cardiovascular and metabolic outcomes. The Daily Mile (TDM) is a popular scheme designed to increase children's PA within the school day. Emerging evidence indicates that participation in TDM can increase children's PA, reduce sedentarism and reduce skinfold measures. However, little is known about the potential effects of TDM as a public health intervention, and the benefits and disbenefits that might flow from wider implementation in 'real world' settings. METHODS: We aimed to identify how TDM is being implemented in a naturalistic setting, and what implications this has for its potential impact on population health. We undertook a rapid ethnographic assessment of uptake and implementation in Lewisham, south London. Data included interviews (n = 22) and focus groups (n = 11) with stakeholders; observations of implementation in 12 classes; and analysis of routine data sources to identify school level factors associated with uptake. RESULTS: Of the 69 primary schools in one borough, 33 (48%) had adopted TDM by September 2018. There were no significant differences between adopters and non-adopters in mean school population size (means 377 vs 397, P = 0.70), mean percentage of children eligible for free school meals (16.2 vs 14.3%, P = 0.39), or mean percentage of children from Black and Minority Ethnic populations (76.3 vs 78.2%, P = 0.41). Addressing obesity was a key incentive for adoption, although a range of health and educational benefits were also hypothesised to accrue from participation. Mapping TDM to the TIDierR-PHP checklist to describe the intervention in practice identified that considerable adaption happened at the level of borough, school, class and pupil. Population health effects are likely to be influenced by the interaction of intervention and context at each of these levels. CONCLUSIONS: Examining TDM in 'real world' settings surfaces adaptions and variations in implementation. This has implications for the likely effects of TDM, and points more broadly to an urgent need for more appropriate methods for evaluating public health impact and implementation in complex contexts.

Towards 'smart cities' as 'healthy cities': health equity in a digital age.

The advent of 'smart' technologies has already transformed urban life, with important consequences for physical, mental, and social well-being. Population health and equity have, however, been conspicuously absent from much of the 'smart cities' research and policy agenda. With this in mind, we argue for a re-conceptualization of 'digital divides' in terms of socio-economic gradients at the individual level, and we draw attention to digitally mediated connections as crucial elements for health promotion at an institutional level and for remedying inequities. We do so in part by reporting on a recent symposium. Overall, we begin to integrate the 'healthy cities' tradition with the current interest in 'smart cities'.

A model of how targeted and universal welfare entitlements impact on material, psycho-social and structural determinants of health in older adults.

A growing body of research attests to the impact of welfare regimes on health and health equity. However, the mechanisms that link different kinds of welfare entitlement to health outcomes are less well understood. This study analysed the accounts of 29 older adults in England to delineate how the form of entitlement to welfare and other resources (specifically, whether this was understood as a universal entitlement or as targeted to those in need) impacts on the determinants of health. Mechanisms directly affecting access to material resources (through deterring uptake of benefits) have been well documented, but those that operate through psychosocial and more structural pathways less so, in part because they are more challenging to identify. Entitlement that was understood collectively, or as arising from financial or other contributions to a social body, had positive impacts on wellbeing beyond material gains, including facilitating access to important health determinants: social contact, recognition and integration. Entitlement understood as targeted in terms of individualised concepts of need or vulnerability deterred access to material resources, but also fostered debate about legitimacy, thus contributing to negative impacts on individual wellbeing and the public health through the erosion of social integration. This has important implications for both policy and evaluation. Calls to target welfare benefits at those in most need emphasise direct material pathways to health impact. We suggest a model for considering policy change and evaluation which also takes into account how psychosocial and structural pathways are affected by the nature of entitlement.

The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis.

BACKGROUND: Many local authorities in England and Wales have reduced street lighting at night to save money and reduce carbon emissions. There is no evidence to date on whether these reductions impact on public health. We quantified the effect of 4 street lighting adaptation strategies (switch off, part-night lighting, dimming and white light) on casualties and crime in England and Wales. METHODS: Observational study based on analysis of geographically coded police data on road traffic collisions and crime in 62 local authorities. Conditional Poisson models were used to analyse longitudinal changes in the counts of night-time collisions occurring on affected roads during 2000-2013, and crime within census Middle Super Output Areas during 2010-2013. Effect estimates were adjusted for regional temporal trends in casualties and crime. RESULTS: There was no evidence that any street lighting adaptation strategy was associated with a change in collisions at night. There was significant statistical heterogeneity in the effects on crime estimated at police force level. Overall, there was no evidence for an association between the aggregate count of crime and switch off (RR 0.11; 95% CI 0.01 to 2.75) or part-night lighting (RR 0.96; 95% CI 0.86 to 1.06). There was weak evidence for a reduction in the aggregate count of crime and dimming (RR 0.84; 95% CI 0.70 to 1.02) and white light (RR 0.89; 95% CI 0.77 to 1.03). CONCLUSIONS: This study found little evidence of harmful effects of switch off, part-night lighting, dimming, or changes to white light/LEDs on road collisions or crime in England and Wales.

Understanding welfare conditionality in the context of a generational habitus: A qualitative study of older citizens in England.

In many welfare states, 'austerity' policies have ignited debates about the fairness and cost-effectiveness of universal welfare benefits, with benefits received by older citizens a particular topic of concern. Empirical studies suggest that conditionality generates problems of access and uptake but, to date, there has been little research on how different conditions of entitlement are understood by older citizens. This study drew on interviews with 29 older citizens from three areas of England to explore how eligibility for and uptake of different kinds of welfare benefits were understood. In interviews, current entitlement was understood in relation to a generational habitus, in which 'our generation' was framed as sharing cohort experiences, and moral orientations to self-reliance, hard work and struggle. Entitlement to some welfare benefits was taken for granted as a reward owed by the state to its citizens for hard-earned lives. State transfers such as pensions, free travel and fuel subsidies were congruent with a nationalised generational habitus, and fostered recognition, self-worth and the sense of a generation as a collective. In contrast, transfers contingent on economic or need-based conditionality were more explicitly framed as 'benefits', and negatively associated with vulnerability and moral contestation. Uptake was therefore often incompatible with their generational habitus. Calls for introducing further conditionality to benefits for older adults are often based on claims that this will increase fairness and equality. Our analysis suggests, however, that introducing conditionality has the potential to promote inequality and foster differentiation and division, within the older population and between generations.

Reduced street lighting at night and health: A rapid appraisal of public views in England and Wales.

Financial and carbon reduction incentives have prompted many local authorities to reduce street lighting at night. Debate on the public health implications has centred on road accidents, fear of crime and putative health gains from reduced exposure to artificial light. However, little is known about public views of the relationship between reduced street lighting and health. We undertook a rapid appraisal in eight areas of England and Wales using ethnographic data, a household survey and documentary sources. Public concern focused on road safety, fear of crime, mobility and seeing the night sky but, for the majority in areas with interventions, reductions went unnoticed. However, more private concerns tapped into deep-seated anxieties about darkness, modernity 'going backwards', and local governance. Pathways linking lighting reductions and health are mediated by place, expectations of how localities should be lit, and trust in local authorities to act in the best interests of local communities.

Working for the public health: politics, localism and epistemologies of practice.

The recent move of public health back to English local government has reignited debates about the role of a medicalised public health profession. The explicit policy rationale for the move was that local government is the arena in which the social determinants of health can be addressed, and that public health specialists could provide neutral evidence to support action on these. However, if a discourse of 'evidence-based' policy is in principle (if not practice) relatively unproblematic within the health arena, within the more overtly politicised local government space, rather different policy imperatives come to the fore. Responding to calls for research on evidence in practice, this article draws on ethnographic data of local authorities in the first year of the reorganised public health function. Focusing on alcohol policy, we explore how decisions that affect public health are rationalised and enacted through discourses of localism, empiricism and holism. These frame policy outcomes as inevitably plural and contingent: a framing which sits uneasily with normative discourses of evidence-based policy. We argue that locating public health in local government necessitates a refocusing of how evidence for public health is conceptualised, to incorporate multiple, and political, understandings of health and wellbeing.

'One health' and development priorities in resource-constrained countries: policy lessons from avian and pandemic influenza preparedness in Zambia.

'One World, One Health' has become a key rallying theme for the integration of public health and animal health priorities, particularly in the governance of pandemic-scale zoonotic infectious disease threats. However, the policy challenges of integrating public health and animal health priorities in the context of trade and development issues remain relatively unexamined, and few studies to date have explored the implications of global disease governance for resource-constrained countries outside the main centres of zoonotic outbreaks. This article draws on a policy study of national level avian and pandemic influenza preparedness between 2005 and 2009 across the sectors of trade, health and agriculture in Zambia. We highlight the challenges of integrating disease control interventions amidst trade and developmental realities in resource-poor environments. One Health prioritizes disease risk mitigation, sidelining those trade and development narratives which speak to broader public health concerns. We show how locally important trade and development imperatives were marginalized in Zambia, limiting the effectiveness of pandemic preparedness. Our findings are likely to be generalizable to other resource-constrained countries, and suggest that effective disease governance requires alignment with trade and development sectors, as well as integration of veterinary and public health sectors.

Look who's walking: social and environmental correlates of children's walking in London.

A substantial literature examines the social and environmental correlates of walking to school but less addresses walking outside the school commute. Using travel diary data from London, we examined social and environmental correlates of walking: to school; outside the school commute during term time; and during the summer and weekends. Living in a household without a car was associated with all journey types; 'Asian' ethnicity was negatively associated with walking for non-school travel; environmental factors were associated with non-school journeys, but not the school commute. Interventions aiming to increase children's active travel need to take account of the range of journeys they make.

Cycling and the city: a case study of how gendered, ethnic and class identities can shape healthy transport choices.

As a form of 'active transport', cycling has been encouraged as a route to improving population health. However, in many high-income countries, despite being widely seen as a 'healthy' choice, few people do cycle for transport. Further, where cycling is rare, it is not a choice made equally across the population. In London, for instance, cycling is disproportionately an activity of affluent, White, men. This paper takes London as a case study to explore why the meanings of cycling might resonate differently across urban, gendered, ethnic and class identities. Drawing on qualitative interview data with 78 individuals, we suggest first that the relative visibility of cycling when few do it means that it is publicly gendered in a way that more normalised modes of transport are not; conversely, the very invisibility of Black and Asian cyclists reduces their opportunities to see cycling as a candidate mode of transport. Second, following Bourdieu, we argue that the affinities different population groups have for cycling may reflect the locally constituted 'accomplishments' contained in cycling. In London, cycling represents the archetypal efficient mode for autonomous individuals to travel in ways that maximise their future-health gain, and minimise wasted time and dependence on others. However, it relies on the cultivation of a particular 'assertive' style to defend against the risks of road danger and aggression. While the identities of some professional (largely White) men and women could be bolstered by cycling, the aesthetic and symbolic goals of cycling were less appealing to those with other class, gendered and ethnic identities.

Modernisation as a professionalising strategy: the case of critical care in England.

There has been broad agreement about how to characterise the processes of 'modernisation' of the public sector in welfare societies, but rather less consensus on the impact of this modernisation on professionals. This paper takes critical care in England as a case study to explore how professionals in one setting account for the changes associated with modernisation. In contrast to reports from other arenas, critical care professionals were positive about the processes and outcomes of 'modernisation' in general, and there was a surprising lack of nostalgia in their accounts of organisational changes. However, joking comments suggested considerable scepticism about the initiatives explicitly associated with the national organisation that was charged with 'modernising' critical care, the Modernisation Agency. We suggest that the relative optimism of staff is in part explained by historical and political contingencies which meant that critical care, as a relatively new clinical specialty, benefited in tangible ways from modernisation. Further, all staff groups were able to attribute gains, rather than losses, in autonomy and authority to the modernisation of critical care. Their accounts suggest that modernisation can be a professionalising strategy, with responses to change being neither resistant nor compliant, but sceptically strategic.

The impact of 20 mph traffic speed zones on inequalities in road casualties in London.

BACKGROUND: Road traffic casualties show some of the widest socioeconomic differentials of any cause of morbidity or mortality, and as yet there is little evidence on what works to reduce them. This study quantified the current and potential future impact of the introduction of 20 mph zones on socioeconomic inequalities in road casualties in London. METHODS: An observational study based on analysis of geographically coded police road casualties data, 1987-2006. Changes in counts of casualties from road collisions, those killed and seriously injured and pedestrian injuries by quintile of deprivation were calculated. RESULTS: The effect of 20 mph zones was similar across quintiles of socioeconomic deprivation, being associated with a 41.8% (95% CI 21.0% to 62.6%) decline in casualties in areas in the least deprived quintile versus 38.3% (31.5% to 45.0%) in the most deprived quintile. Because of the greater number of road casualties in deprived areas and the targeting of zones to such areas, the number of casualties prevented by zones was substantially larger in areas of greater socioeconomic deprivation. However, the underlying decline in road casualties on all roads was appreciably greater in less deprived areas (p<0.001 for trend) so that despite the targeting of 20 mph zones, socioeconomic inequalities in road injuries in London have widened over time. Extending 20 mph schemes has only limited the potential to reduce differentials further. CONCLUSIONS: The implementation of 20 mph zones targeted at deprived areas has mitigated widening socioeconomic differentials in road injury in London and to some degree narrowed them, but there is limited potential for further gain.

'Not quite Jericho, but more doors than there used to be'. Staff views of the impact of 'modernization' on boundaries around adult critical care services in England.

OBJECTIVES: To explore staff perceptions of the impact of 'modernization' on the organization, delivery and culture of adult critical care services in England. 'Modernization' policies aimed to alter the boundaries around critical care and create a comprehensive, seamless service. METHODS: Seven hospitals (three teaching and four district general hospitals) in three critical care networks participated. In-depth interviews were conducted with a purposive sample of 45 critical care staff. Data were analysed thematically. RESULTS: The boundaries around critical care were generally perceived to be less fixed than previously. The re-framing of 'internal walls' within hospitals was associated with the introduction of outreach teams, new hospital-wide remits for intensive care unit (ICU) staff and the greater integration of allied health professionals into the critical care team. Transformation of services was challenged by practicalities including the need for additional staff, and a 'them and us' attitude between ICU and ward staff. 'External walls' between hospitals were breached where local clinical networks were perceived to have successfully improved communication and joint working. This was facilitated by effective leadership, availability of network-associated funds, the identification of common problems and evidence of benefit from cooperation. However, barriers existed and there was some scepticism among staff as to whether critical care can ever be entirely 'without walls'. CONCLUSIONS: Policies to remove boundaries around adult critical care are perceived to have had a dramatic impact on the organization of the service. Considerable progress was reported towards developing comprehensive critical care services both within and between hospitals.

Evaluation of modernisation of adult critical care services in England: time series and cost effectiveness analysis.

OBJECTIVE: To evaluate the impact and cost effectiveness of a programme to transform adult critical care throughout England initiated in late 2000. DESIGN: Evaluation of trends in inputs, processes, and outcomes during 1998-2000 compared with last quarter of 2000-6. SETTING: 96 critical care units in England. PARTICIPANTS: 349,817 admissions to critical care units. INTERVENTIONS: Adoption of key elements of modernisation and increases in capacity. Units were categorised according to when they adopted key elements of modernisation and increases in capacity. MAIN OUTCOME MEASURES: Trends in inputs (beds, costs), processes (transfers between units, discharge practices, length of stay, readmissions), and outcomes (unit and hospital mortality), with adjustment for case mix. Differences in annual costs and quality adjusted life years (QALYs) adjusted for case mix were used to calculate net monetary benefits (valuing a QALY gain at pound20,000 ($33,170, euro22 100)). The incremental net monetary benefits were reported as the difference in net monetary benefits after versus before 2000. RESULTS: In the six years after 2000, the risk of unit mortality adjusted for case mix fell by 11.3% and hospital mortality by 13.4% compared with the steady state in the three preceding years. This was accompanied by substantial reductions both in transfers between units and in unplanned night discharges. The mean annual net monetary benefit increased significantly after 2000 (from pound402 ($667, euro445) to pound1096 ($1810, euro1210)), indicating that the changes were relatively cost effective. The relative contribution of the different initiatives to these improvements is unclear. CONCLUSION: Substantial improvements in NHS critical care have occurred in England since 2000. While it is unclear which factors were responsible, collectively the interventions represented a highly cost effective use of NHS resources.

Forty-eight hour access to primary care: practice factors predicting patients' perceptions.

BACKGROUND: The government has proposed a 48-hour target for GP availability. Although many practices are moving towards delivering that goal, recent national patient surveys have reported a deterioration in patients' reports of doctor availability. What practice factors contribute to patients' perceptions of doctor availability? METHOD: A cross sectional patient survey (11,000 patients from 54 inner London practices, 7247 (66%) respondents) using the General Practice Assessment Survey. We asked patients how soon they could be seen in their practice following non-urgent consultation requests and related their aggregated responses to the characteristics of their practice. RESULTS: Three factors relating to practice administration and appointments systems operation independently predicted patients' reports of doctor availability. These were the proportion of patients asked to attend the surgery and wait to be seen, the proportion of patients seen using an emergency surgery arrangement, and the extent of practice computerization. CONCLUSION: Some practices may have difficulty in meeting the target for GP availability. Meeting the target will involve careful review of practice administrative procedures.