Analysing the effectiveness and cost effectiveness of mental health promotion is inherently difficult for a number of reasons. These include the following:
Mental health remains a contested concept which can be defined and measured in various ways. the conceptualisation in positive rather than negative terms which
is now central to policy frameworks for mental health promotion puts the focus on positive indicators of well-being, but these are still in the development stage.
better mental health is worthwhile not only in its own right but also because it leads to improved outcomes in a range of other domains. capturing these indirect benefits in evaluation studies raises various problems of coverage, measurement and attribution.
The benefits of improved mental health are not only multi-dimensional but may also accrue over many years, even a lifetime in the case of childhood interventions. this can give rise to serious difficulties of length as well as breadth of analysis in research work.
Mental health is subject to many influences and the impact of a specific intervention may be difficult to disentangle from the effects of confounding factors. Statistical associations between mental health and other variables are often open to interpretation, concerning for example the direction of causation.
Policy interventions take a wide variety of forms; for example, some may be targeted on high-risk individuals whereas the focus of others is community-wide.Research methods need to reflect such variety, but the use of different evaluative approaches can lead to problems of comparability and consistency. the randomised controlled trial, often seen as the gold standard for health research, is most suitable for single-component interventions in highly controlled settings, but many interventions to promote mental health do not take this form.
the working of many interventions, particularly those targeted on individuals, will be mediated by broad structural factors such as poverty or unemployment. the role of socio-economic context needs to be taken into account in evaluation studies but this is rarely straightforward. These and other difficulties in the analysis of mental health promotion have two main consequences. First, there remain significant gaps in the evidence base. this is particularly so in the area of cost effectiveness. Few published studies contain primary economic data on costs and benefits and, among those that do, the coverage is usually incomplete; for example, the collection of financial information is often confined to effects on the public sector. Second, the evidence base may be subject to various forms of bias. For example, some types of intervention are easier to evaluate than others, resulting in the likely availability of more studies – with more conclusive results – in the former area. Similarly, some components of cost and benefit are easier to identify and collect than others. In general, costs are easier to measure than benefits, particularly long term benefits. The available evidence may therefore systematically understate the net returns on mental health promotion, particularly those interventions which have long-lasting effects.