The vast majority of established so-called health indicators in use today do not really focus on health per se. Of the 27 items that are included in the "health status" category of the WHO global "core" set, 25 relate to mortality or morbidity, and two to fertility. The remaining 73 indicators address risk factors for diseases (n = 21), healthcare service coverage (n = 27) or different aspects of the healthcare system (n = 27) such as quality of care, access to services, characteristics of the workforce, information management and financing (37).

A much more sensible approach, as it is the case with constructs related to humans experience, is to ask people what they think about their own health, as the starting point.

Although this has been done for decades as part of quality of life research or large population-based studies, self-reported (also known as self-rated or self-assessed) health judgements have rarely been used to guide policy, financial or clinical decisions, perhaps because they are perceived as "too soft".

Nevertheless, such assessments are easy and cheap to obtain, have shown remarkable validity and predictive power, and align well with the new conceptualization of health (38).

The assessments are typically obtained in response to a single question that is most often asked using one of two highly correlated versions (39). The American version typically reads thus: "In general, how would you rate your health today: excellent, very good, good, fair or poor?" The version favoured by the WHO is almost always presented thus "In general, how would you rate your health today: very good, good, moderate, bad or very bad?"

Once the assessments are obtained, they can be easily categorized into two groups. Using the American version of the question, individuals who choose to respond "good", "very good" or "excellent" could be considered as having positive health, while those who respond "poor" or "fair" are deemed to have negative health. A similar picture emerges when "good" is used as the cut off point with the WHO version.

Despite the discomfort that such openly subjective assessments produce among those who prefer "harder" indicators such as laboratory tests, death rates or life expectancy, self-assessments of health are highly predictive of short- and long-term mortality, even after adjustment for functional status, known disease risk factors and socioeconomic status, depression and comorbidity (40-46). Self-reports also been shown to predict decline in physical functioning (47,48), and significant reductions in emergency room use (49) and aggregate health expenditures (50). Negative health, on the other hand, has been associated with a doubling in mortality rates (45,51), as well as increased prevalence of a large list of chronic conditions including cardiovascular and cerebrovascular diseases, visual impairment and mental disorders (41,52).