Measuring concerns for severity: re-examination of a health scale with purported equal interval properties

Severity of illness is an important official criterion for priority setting in health care in a number of jurisdictions. An 8-point scale of severity and functional status has been used in a number of studies in Norway in order to estimate the strength of concerns for severity in population samples. The scale has attracted international attention and may be of interest to researchers in other countries. For confidence in interpretations of results, the scale should have equal interval properties with respect to individual utility. Close examination suggest that some deviations from equal intervals occur. These deviations do not impact significantly on earlier findings and do not prevent the scale from being a potentially useful tool in future studies of the strength of societal concerns for fairness in health care. However, further research with larger and more representative samples is encouraged.