A new short form individual quality of life measure (SEIQoL-DW): application in a cohort of individuals with HIV/AIDS

Publisher Website
Google Scholar
Abstract
Measuring the quality of lifeThe methodology used to evaluate quality of life has received considerable attention in the past decade.1 2 3 4 Traditional questionnaires impose an external value system, and weighting of the component parts of the questionnaire is standardised and fixed and is generally derived from grouped data. Although these measures may be reliable, they may not be relevant to an individual's present life situation. Apparently similar behaviours do not have the same relevance or importance for all individuals. Furthermore, the relevance or importance of particular behaviours or events does not necessarily remain static for a given individual with the passage of time or over the course of an illness.5 Thus, for valid measurement of quality of life a measure is needed that evaluates each individual on the basis of the areas of life that he or she considers to be most important, quantifies current functioning in each of these personally nominated life areas, and weights their relative importance for that individual at that particular time. A life area that is going badly for an individual but is of little importance to him or her clearly has less implication for that individual's quality of life than a life area that is going badly but is of great importance.The schedule for the evaluation of individual quality of life (SEIQoL) was developed to assess quality of life from the individual's perspective.5 6 7 It is an interview based instrument derived from a decision analysis technique known as judgment analysis.8 9 10 The investigator can assess the level of functioning in, and relative importance of, those areas of life nominated by the respondent. The SEIQoL is a complex measure of a complex process and its use in routine clinical situations may prove impractical. We describe an abbreviated form of the measure, the SEIQoL-direct weighting (SEIQoL-DW),11 12 which replaces the more cumbersome judgment analysis technique with a simpler procedure for measuring the relative importance (weights) to the respondent of nominated life areas.The direct weighting instrument is a simple apparatus consisting of five interlocking, coloured laminated circular disks that can be rotated around a central point to form a type of pie chart. The laminated disks are mounted on a larger backing disk, which displays a scale from 0 to 100, and from which the relative size of each coloured segment can be read (fig 1). Each segment is labelled with a life area nominated by the respondent as being important to his or her overall quality of life. The respondent adjusts the disks until the size of each coloured segment corresponds to the relative importance of the life area represented by that segment. These segments may be adjusted and readjusted until respondents are satisfied that the proportion of the pie chart given to each life area accurately reflects the relative weights they attach to those life areas. If the respondent nominates fewer than five cues, the system allows for a corresponding number of segments to be manipulated. The weighting procedure is quick to administer, colourful, tactile, and easy to understand. The SEIQoL-DW was developed and validated against the full version of the SEIQoL and found to be a valid and reliable measure of explicit weighting policies for quality of life domains.11View larger version: In this window In a new window Fig 1 The segments represent five areas of life nominated by the individual; the size of the segment can be adjusted to show the relative importance of each area for the individual's quality of lifePSYCHOMETRIC PROPERTIESDetailed psychometric properties of the SEIQoL-DW will be reported elsewhere and are available from the authors. Studies in healthy subjects have indicated that the measure is reproducible and has high criterion validity. While the weights derived from the direct weighting and the full judgment analysis procedures are similar, there are some differences. The findings suggest that the SEIQoL-DW may be measuring explicit weights about which the respondent is consciously aware, whereas the full measure may incorporate elements of judgment which are implicit and about which the respondent is unaware but which may have a bearing on the overall judgment.11