Perception survey on the relevance of main categories of health determinants for conducting health impact assessment

The gross inequalities in health that we see within and between countries present a challenge to the world. That there should be a spread of life expectancy of 48 years among countries and 20 years or more within countries is not inevitable. A burgeoning volume of research identifies social factors at the root of much of these inequalities in health. Social determinants are relevant to communicable and non-communicable disease alike. Health status, therefore, should be of concern to policy makers in every sector, not solely those involved in health policy. As a response to this global challenge, WHO is launching a Commission on Social Determinants of Health, which will review the evidence, raise societal debate, and recommend policies with the goal of improving health of the world's most vulnerable people. A major thrust of the Commission is turning public-health knowledge into political action.

Sample size calculation is part of the early stages of conducting an epidemiological, clinical or lab study. In preparing a scientific paper, there are ethical and methodological indications for its use. Two investigations conducted with the same methodology and achieving equivalent results, but different only in terms of sample size, may point the researcher in different directions when it comes to making clinical decisions. Therefore, ideally, samples should not be small and, contrary to what one might think, should not be excessive. The aim of this paper is to discuss in clinical language the main implications of the sample size when interpreting a study.

Objectives To examine existing definitions of health and health inequalities and to synthesise the most useful of these using explicit rationale and the most parsimonious text. Study design Literature review and synthesis. Methods Existing definitions of health and health inequalities were identified, and their normative properties were extracted and then critically appraised. Using explicit reasoning, new definitions, synthesising the most useful aspects of existing definitions, were created. Results A definition of health as a structural, functional and emotional state that is compatible with effective life as an individual and as a member of society and a definition of health inequalities as the systematic, avoidable and unfair differences in health outcomes that can be observed between populations, between social groups within the same population or as a gradient across a population ranked by social position are proposed. Population health is a less commonly used term but can usefully be defined to encompass the average, distribution and inequalities in health within a society. Conclusions Clarifying what is meant by the terms health and health inequalities, and the assumptions, emphasis and values that different definitions contain, is important for public health research, practice and policy.