Mapping the Gastrointestinal Quality of Life Index to short-form 6D utility scores.

TitleMapping the Gastrointestinal Quality of Life Index to short-form 6D utility scores.
Publication TypeJournal Article
Year of Publication2014
AuthorsLee L, Kaneva P, Latimer E, Feldman LS
JournalJ Surg Res
Date Published2014 Jan
KeywordsAdult, Aged, Cholecystectomy, Laparoscopic, Female, Health Status, Humans, Least-Squares Analysis, Male, Middle Aged, Quality of Life, Quality-Adjusted Life Years

PURPOSE: The Gastrointestinal Quality of Life Index (GIQLI) is a disease-specific quality of life instrument that is commonly used in gastrointestinal disorders. However, no preference weights, which are used to calculate quality-adjusted life years for cost-effectiveness analyses, for this instrument have been assigned. Therefore, the objective of this study was to develop a mapping function to derive utility scores for the GIQLI.METHODS: Patients undergoing elective laparoscopic cholecystectomy completed the short-form 6D (SF-6D), a preference-weighted utility measure, and the GIQLI at baseline and at 1 wk and 1 mo postoperatively. The responsiveness of the SF-6D to expected postoperative changes as well as the correlation between the SF-6D and the GIQLI was investigated. Ordinary least squares regression was performed to derive a mapping function using the baseline values, which was then validated using postoperative values. Adjusted r(2), mean absolute error, and root mean square error was used to determine model performance.RESULTS: A total of 50 patients were included in the study (mean age 51.1 [standard deviation 16.8], 28% male). The SF-6D and GIQLI domains were responsive to expected postoperative changes, and there was high correlation between the SF-6D and four of the five GIQLI domains (excluding treatment effects). The final mapping function explained 63% of the variance in the derivation sample but had relatively high mean absolute error (0.075 and 0.067 in the 1-wk and 1-mo samples, respectively) and adjusted root mean square error (13.1% and 12.0% in the 1-wk and 1-mo samples, respectively).CONCLUSIONS: The GIQLI can be accurately mapped to SF-6D preference weights at the group level but may be too inexact at the individual level.

Alternate JournalJ. Surg. Res.
PubMed ID24021906