HUI questionnaires are designed to map onto two classification systems, HUI-2 and HUI-3, capable of measuring 24,000 and 972,000 unique health states, respectively.
HUI classifications measure a range of health domains with examples including sensation, mobility, pain, cognition, ambulation, and emotion.
[1] Originally developed by McMaster University in Canada, HUI has subsequently evolved and been adapted by Health Utilities Inc.
The purpose of developing HUI was to create a standardized classification system using preference-based scoring.
[2] HUI was modeled using multi-attribute utility theory to assess a participants overall health-related quality of life.
HUI was first used to evaluate HRQoL in very-low birth weight infants and adolescent cancer morbidity and has since been taken by thousands of respondents from hundreds of researchers.
[1] The attribute categories were decided upon after consulting the general public to rank their order of importance.
[citation needed] HUI-2 classification system consists of 7 attributes including sensation, mobility, emotion, cognition, self-care, pain and fertility.
Fertility is not currently used in the HUI-2 questionnaire, but was included historically to account for the effects of infertility on health-related quality of life.
A unique health state is described as a sequence of numbers based on the level selected for each attribute.
Negative values account for the fact that some health states are identified by the general public as being worse than death.
Each attribute and level has a corresponding coefficient value to be input into the formula to calculate health utility.
A health state for a respondent of the following: The corresponding coefficients associated with each attribute and level are entered into the above formula as:
The adjustment accounts for the changes in health-related quality of life for a given health state as a result of treatment.
[6] Since its introduction in 1991, HUI questionnaires and classification systems have been translated into 35 different languages and have been used by 300 investigators across 20 different countries around the world.
[1] Research has demonstrated that HUI provides comparable measures of general health status to the SF-36 and EQ-5D, other well established questionnaires used in this field.