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21.5  Ethics and inequalities

Public health and health promotion interventions have the potential to improve the health of populations. Systematic reviews can determine the effectiveness of these interventions in achieving their desired outcomes. There are some specific ethical considerations that should be taken into account in reviewing the effectiveness of public health and health promotion interventions. Effectiveness is typically measured in terms of the total number (population) who benefit from the intervention. This consequentialist approach takes no account of the distribution of benefits (Hawe 1995), and therefore does not address issues of health equity. Overall improvements in health behaviours or health outcomes may actually mask the differences in health outcomes between groups (Macintyre 2003). Interventions that work for those in the middle and upper socio-economic positions may not be as effective for those who are disadvantaged. Even well-intentioned interventions may actually increase inequalities. Health differentials that exist between groups may be due to complex interactions between many of the factors relating to disadvantage (Jackson 2003).


Systematic reviews of public health and health promotion interventions have the potential to investigate differential outcomes for groups with varying levels of disadvantage. This is important as identifying the effect of interventions on disadvantaged groups can inform strategies aimed at reducing health inequalities and health inequities. Health inequalities are “differences, variations, and disparities in the health achievements of individuals and groups” (Kawachi 2002). Health equity is an ethical concept referring to the fairness or unfairness of particular health inequalities. The International Society for Equity in Health defines equity in health as: “the absence of potentially remediable, systematic differences in one or more aspects of health status across socially, economically, demographically, or geographically defined populations or subgroups” (Macinko 2002). Turning this around, health inequities are those health inequalities that are unfair or unjust, or stem from some kind of injustice (Kawachi 2002). Reviews of effectiveness of public health and health promotion interventions can provide information about the effects of interventions on health inequalities. This information can then be used to address health inequities.


Disadvantage may be considered in terms of place of residence, race or ethnicity, occupation, gender, religion, education, socio-economic position (SES) and social capital, known by the PROGRESS acronym (Evans 2003). Authors should carefully consider which of these are relevant to their population of interest; data will then be extracted by these factors. The Cochrane Health Equity Field and Campbell Equity Methods Group are working on definitions of equity as relevant to Cochrane reviews:


Systematic reviews rely upon there being sufficient detail in study data to allow for identification of relevant subgroups for analysis in relation to health inequalities. This requires attention not only to levels of benefit or harm, but also to the distributions of these: who is benefiting, who is harmed, who is excluded?


Reviews of the effectiveness of interventions in relation to health inequalities require three components for calculation:

Review authors should decide which indicator(s) of disadvantage or status are relevant to the review topic. There are many factors that relate to disadvantage (acronym PROGRESS) and authors will need to collect data on any of the factors likely to be relevant to their population of interest (PROGRESS = residence, race or ethnicity, occupation, gender, religion, education, socio-economic position (SES) and social capital).


Conducting reviews addressing inequalities is complicated not only by limited collection of information about differences between groups, but also by the fact that there is limited participation of disadvantaged groups in research. Despite these barriers, systematic reviews can play an important role in raising awareness of health inequalities. The Cochrane Health Equity Field and Campbell Equity Methods Group have identified a number of equity-relevant reviews that may provide additional guidance for authors.


To locate studies that examine inequalities, review authors will need to cast the net broadly when performing searches and contact authors for further information regarding socio-economic data. This latter task may be necessary because primary studies often fail to present information on the socio-economic composition of participants (Oakley 1998, Jackson 2003, Ogilvie 2004). Once studies have been appraised and data have been extracted, studies need to be classified as to whether they are effective for reducing health inequalities. An effective intervention to reduce inequity is generally one that is more effective for disadvantaged groups or individuals. A potentially effective intervention for reducing inequities is one that is equally effective across the socio-economic spectrum (may reduce health inequalities due to the prevalence of health problems among the disadvantaged being greater). The judgement becomes more difficult when the intervention is targeted only at disadvantaged individuals or groups. In a Cochrane review of school feeding problems, effective interventions aimed solely at disadvantaged children were labelled as ‘potentially’ effective in reducing socio-economic inequalities in health (Kristjansson 2007). It is impossible to determine differential effectiveness if studies comprise mixed levels of advantage and disadvantage but do not include results that can be broken down by socio-economic (or similar) grouping.