Concerns for severity in priority setting in health care: a review of trade-off data in preference studies and implications for societal willingness to pay for a QALY.

OBJECTIVE: In a wide range of health care jurisdictions, to give priority to the severely ill over the less severely ill is important in decisions about resource allocation across patient groups. We summarise data on concerns for severity measured at a cardinal level in preference studies in various countries and show how the data may provide guidance for determining severity graded willingness to pay for a QALY.
METHODS: We review evidence in 15 articles published in peer reviewed journals in the time period 1978-2010, with reports from altogether 20 individual studies in 9 different countries. The studies all focus on the quality of life dimension of severity, i.e. utility losses on the 0-1 scale used in QALY-calculations. We report 116 individual observations of paired comparisons of utility improvements with different start levels. We argue that the strength of concerns observed on the quality of life dimension may be assumed to apply also to losses in length of life and thus to severity in terms of proportional shortfall of QALYs. By means of regression analyses we estimate a severity gradient in each study that suggests the span in societal willingness to pay for a QALY to people at high and low levels of severity respectively.
RESULTS: Concerns for severity show up quite strongly across countries, sample types and question framings, although the size of the severity gradient varies very much. Interested policy makers may hopefully find the central tendency in the results to be useful as an input to determining severity dependent willingness to pay for a QALY.