There is an increasing focus on the measurement of the health outcomes of healthcare interventions. Purchasers of health services want to know how much patients' lives will be improved by potential treatments, evidence of their effectiveness and costs and information about health gain in the broadest sense. But the conceptualization and methods of measurement of health outcomes is still controversial.

In order to measure health outcomes a measure of health status is required which needs to be based on a concept of health. Health indicators have largely been developed within the era of science based on the logical positivist paradigm. This inevitably leads to suspicion when data are presented which are based on subjective experience, rather than objective indicators. Clinicians have traditionally judged the value of an intervention mainly in terms of the five-year survival period. While obviously important in the case of life-threatening conditions, this indicator ignores the living. Many healthcare programmes and interventions will have little or no impact on mortality rates (e.g. in relation to chronic diseases). Survival needs to be interpreted more broadly in terms of the impact and consequences of treatment. And a person's ‘ill health’ is indicated by feelings of pain and discomfort or perceptions of change in usual functioning and feeling. Illnesses can be the result of pathological abnormality, but not necessarily so. A person can feel ill without medical science being able to detect disease.