Background
Socio-economic inequalities are associated with unequal exposure to social, economic and environmental risk factors, which in turn contribute to health inequalities. People with higher income, employment and educational opportunities have lower mortality and morbidity [
1]. Social inequalities in health are widespread, for example in Europe where an estimated 80 million people are living in relative poverty [
2]. Important European differences in health outcomes have been attributed to variations in how the welfare state is administered [
3,
4]. The welfare state is therefore potentially an important macro-level determinant of health which also moderates the extent, and impact, of socio-economic inequalities in exposure to the social determinants of health. The welfare state has three main policy domains: health care, social policy (e.g. social transfers and education) and public health policy. This planned umbrella review examines the latter; its aim is to assess how European welfare states influence the social determinants of health inequalities institutionally through public health policies. Understanding the impact of specific public health policy interventions will help to establish causality in terms of the effects of welfare states on population health. This review will therefore help identify effective interventions that could be implemented to reduce health inequalities between and within European countries.
Many commentators have sought to define what is meant by public health. The World Health Organization [
5] emphasises how public health refers to ‘all organized measures (whether public or private) to prevent disease, promote health, and prolong life among the population as a whole’. The system of administering public health to populations could be the private or voluntary sector, but in European welfare states, it is most usually instigated by governments—centrally, regionally or locally. Welfare states may impact the health of citizens either indirectly through influencing the social determinants of health (e.g. through changes to social policy such as education, social security and housing) or directly through health care systems or policies aimed at promoting public health specifically [
6,
7]. The proposed umbrella review will examine the latter aspect of European welfare states.
Public health policies can operate on a number of different levels, which affects population health and health inequalities. Following Mackenbach and McKee [
8], public health policies may influence primary prevention (which aims to avoid the occurrence of a disease by reducing exposure to health risks) or secondary prevention (which aims to avoid the development of a disease to a symptomatic stage by diagnosing and treating the disease before it causes significant morbidity of the disease) (p. 195). Public health interventions may occur at multiple levels. Downstream interventions involve individual-level behavioural approaches for prevention or disease management, and their success depends on whether some sections of the population are more likely to take up or successfully engage with certain initiatives compared to others [
9]. Upstream interventions involve state or institutional control, regulating the supply of a particular substance or activity, promoting a method of preventative health behaviour or improving the wider environment. These population-level interventions will be the focus for the proposed umbrella review, as they are likely to reduce socio-economic inequalities in health and have the greatest influence on overall population health within a territory [
10‐
13].
The nature of public health interventions means their influence percolates into many aspects of how we behave, live and work. For the purposes of this review, we categorise these interventions into fiscal policy, regulation, education, preventative treatment and screening. It is also helpful to consider the broad areas by which local and national governments may intervene and regulate. An example of the public health domain groupings (and intervention types) we propose can be found in Table
1. These groups are based on the ten areas of public health policy that Mackenbach and McKee [
7,
14] identify as contributing to major population health gains: tobacco; alcohol; food and nutrition; reproductive health services; the control of infectious diseases; screening; mental health; road traffic injuries; air, land and water pollution; and workplace regulations. Whilst acknowledging that this list may not be exhaustive, its inclusion highlights the broad areas that our final report will focus on. Furthermore, distinguishing public health policies from other welfare state policy domains such as social policy may not be clear-cut (the division is based on practicality as a parallel review on social and health care policy is also underway). Public health policies influence almost all aspects of society, but the focus here centres on policies directly influencing health (e.g. the control of infectious diseases), or those indirectly regulating other areas of government regulation policy which have clear and direct pathways to (poor) health (e.g. workplace regulations).
Table 1
Matrix of population-level preventative public health interventions
Description | Using market forces to change demand for products deemed healthy/unhealthy | Making and enforcing regulation to encourage/discourage products and services deemed healthy/unhealthy | Using mass media campaigns to encourage/discourage products and services deemed healthy/unhealthy | Offering population-wide measures to eradicate infectious diseases | Offering age-appropriate population-level screening for certain diseases |
Domains | Scope of domains | | | | | |
Tobacco | Protecting people from second-hand smoke and raising tobacco prices through taxation | ✓ | ✓ | ✓ | | |
Alcohol | Increasing the price limits of alcohol and availability and bans on advertising | ✓ | ✓ | ✓ | | |
Food and nutrition | Regulating supplements of trace minerals (e.g. iodine and fluoride) and tackling nutrition-related risk factors of cardiovascular diseases | ✓ | ✓ | ✓ | | |
Reproductive health services | Fertility (access to contraception and safe abortion, prevention of multiple births in assisted reproduction), pregnancy (protection of pregnant women and children, preventive care in the prenatal period, screening for congenital anomalies), delivery and postpartum care (access to safe delivery care, promotion of breastfeeding) | ✓ | ✓ | ✓ | | ✓ |
The control of infectious diseases | Protecting the health of the public from new or persisting threats, securing what has been achieved (e.g. system breakdown during economic crises or methicillin-resistant Staphylococcus aureus). | | ✓ | ✓ | ✓ | |
Screening | Cancer screening (cervical, breast, colorectal and prostate screening, etc.) and screening for CVD risk factors (e.g. hypertension prevention and control) | | | ✓ | | ✓ |
Mental health | The human rights perspective, scope of mental health policy, intervening with those at risk, intervening with the process of suicide | | ✓ | ✓ | | |
Road traffic injuries | Controlling speed, stopping driving when under the influence of alcohol, enforcing use of safety equipment, increasing conspicuousness, improving vehicle crash protection, making infrastructural changes to road design | | ✓ | ✓ | | |
Air, land and water pollution | Effectiveness of air pollution control policies (sulphur dioxide, particulate matter, nitrogen oxides, ozone). Land and water pollution control policies such as land decontamination | | ✓ | ✓ | | |
Workplace regulations | Working week regulations, workplace health and safety legislation (e.g. around exposures to noise and vibrations) | | ✓ | ✓ | | |
Whilst there are many excellent reviews which focus on specific public health areas (e.g. [
15,
16]), to our knowledge, there is no truly comprehensive umbrella systematic review which has sought to evaluate the full suite of population-level public health policies available to governments. Lorenc et al. [
10] undertook a rapid review searching only one database (Medline) and identified 12 reviews meeting their inclusion criteria. Bambra et al. [
17] conducted a much more complete review which focused on both social and public health policies. However, their searching only spanned the period 2000–2007, and at that time, the authors concluded that the systematic review evidence base was unclear to determine the effects of interventions on health inequalities. Nor did these previous reviews focus on the potential importance of different welfare state context. In recent years, there has been an effort to promote health equity by encouraging authors of systematic reviews to document health inequalities amongst disadvantaged groups through reporting guidelines such as ‘PRISMA-E 2012’ and ‘PROGRESS-PLUS’ [
18‐
20]. It is therefore timely to update these umbrella reviews and comprehensively document population-level public health interventions designed to improve health and reduce health inequalities.
Pilot search strategy
A pilot search strategy has been conducted in Medline (via Ovid) and is shown in Table
3. At each stage, the type of study (pilot 1), intervention (pilot 2) and outcomes (health, pilot 3 and SES, pilot 4) are added. Three key papers were used as examples to see if the different searches located them. Pilot search 1 used a search strategy based primarily on the Health Information Research Unit of McMaster University [
31] and also the Scottish Intercollegiate Guidelines Network (SIGN) filter for systematic reviews [
32]. Additionally, specific reference to umbrella reviews was included to ensure existing umbrella systematic reviews were highlighted and their bibliographic literature added where necessary. This identified over 355,412 records. Next, population-level intervention terms were added (pilot 2). When combined with the systematic review terminology previously searched, the number of hits dropped dramatically to 8,821. Pilot 3 includes examples of outcomes and reduces the number of hits only slightly to 8,550. Adding inequality terminology reduced the number of hits further to ca. 1,700 (pilot 4). Although adding outcome terms (pilots 3 and 4) decreased the number of hits to one fifth compared to just using the type of study and population-level terms (pilot 2), it was felt that these outcome terms should not be included in the final search strategy. Instead, the search strategy advocated in pilot 2 would be used and screening for outcome terms would occur after the initial searches have been conducted. This was in part due to the variety of interventions (and therefore outcomes) which this public health review might highlight. The search strategy will be adapted for each of the specific databases; an example for Medline (Ovid) is shown in Additional file
2.
Table 3
Pilot search strategy using Medline (via Ovid), run from start date to present (11/03/2016)
Search number | 1 | 2 | 3 | 4 |
Search strategy reference (including deviations) | Terms from McMaster University [ 31] and SIGN [ 32] (plus specific umbrella review terminology) | Terms from Bambra et al. [ 27] (changed positional operator (adj) from 3 to 8 and included additional search term using health adj8 to intervention terminology) | Terms from Cairns et al. [ 22] | Terms from Bambra et al. [ 17] (excluding fluoridation and water supply, access to health care, public transport and neighbourhood crime terminology) |
Search strategy details in Additional file 2 including deviations from | Lines 1–6 (excluding animal studies—lines 11–13) | Lines 7 to 10 | Lines 15 and 16 | Lines 17 and 18 |
Number of hits | 355,412 | 8,821 | 8,550 | 1,724 |
Target papers | | | | |
| ✓ | ✓ | ✓ | ✓ |
| ✓ | ✓ | ✓ | ✓ |
| ✓ | ✓ | ✓ | ✓ |
Discussion
This umbrella review will provide evidence of macro, population-level public health interventions which affect health and reduce health inequalities amongst European welfare states. Understanding the impact of specific public health policy interventions will help to establish causality in terms of the effects of welfare states on population health and health inequalities and, most importantly, identify effective interventions that could be implemented to reduce health inequalities across European countries. The umbrella review will consider public health strategies across ten different domains of public health, and, as such, it will also serve as a mapping exercise of the types of interventions that have been systematically reviewed, thereby highlighting any gaps in the systematic review evidence base. The review will also seek to establish (where reported) how such public health interventions are organised, implemented and delivered. Context is increasingly recognised as an important factor in the success of public health interventions [
33] and has begun to be taken into account in systematic reviews. However, the assessment of implementation has not featured strongly in previous umbrella reviews. We will therefore develop and refine existing methodological tools and apply them to umbrella reviews [
33,
34]. The review also adds to the literature that conceptualises public health regulation as one of the three tiers of the welfare state—alongside health care access/provision and social policy [
14].
Competing interests
The authors declare they have no competing interests.
Authors’ contributions
KT led the drafting and revising of the manuscript with the input from CB. AT, CM and TH contributed to the writing and revision of the manuscript. All authors read and approved the final manuscript.