Development of a paper-and-pencil semi-adaptive questionnaire for 5 domains of health-related quality of life (PAT-5D-QOL).

OBJECTIVES: To develop a paper-and-pencil semi-adaptive test for 5 domains of health-related quality of life (PAT-5D-QOL) based on item response theory (IRT). METHODS: The questionnaire uses items from previously developed item banks for 5 domains: (1) walking, (2) handling objects, (3) daily activities, (4) pain or discomfort, and (5) feelings. For each domain, respondents are initially classified into 4 functional levels. Depending on the level, they are instructed to respond to a different set of 5 additional questions. IRT scores for each domain and overall health utility scores are obtained using a simple spreadsheet. The questions were selected using psychometric and conceptual criteria. The format of the questionnaire was developed through focus groups and cognitive interviews. Feasibility was tested in two population surveys. A simulation study was conducted to compare PAT-5D-QOL with a computerized adaptive test (CAT-5D-QOL) and a fixed questionnaire, developed from the same item banks, in terms of accuracy, bias, precision, and ceiling and floor effects. RESULTS: Close to 90 % of the participants in feasibility studies followed the skip instructions properly. In a simulation study, scores on PAT-5D-QOL for all domains tended to be more accurate, more precise, less biased, and less affected by a ceiling effect than scores on a fixed IRT-based questionnaire of the same length. PAT-5D-QOL was slightly inferior to a fully adaptive instrument. CONCLUSIONS: PAT-5D-QOL is a novel, semi-adaptive, IRT-based measure of health-related quality of life with a broad range of potential applications.

Assessment of health-related quality of life in arthritis: conceptualization and development of five item banks using item response theory.

BACKGROUND: Modern psychometric methods based on item response theory (IRT) can be used to develop adaptive measures of health-related quality of life (HRQL). Adaptive assessment requires an item bank for each domain of HRQL. The purpose of this study was to develop item banks for five domains of HRQL relevant to arthritis. METHODS: About 1,400 items were drawn from published questionnaires or developed from focus groups and individual interviews and classified into 19 domains of HRQL. We selected the following 5 domains relevant to arthritis and related conditions: Daily Activities, Walking, Handling Objects, Pain or Discomfort, and Feelings. Based on conceptual criteria and pilot testing, 219 items were selected for further testing. A questionnaire was mailed to patients from two hospital-based clinics and a stratified random community sample. Dimensionality of the domains was assessed through factor analysis. Items were analyzed with the Generalized Partial Credit Model as implemented in Parscale. We used graphical methods and a chi-square test to assess item fit. Differential item functioning was investigated using logistic regression. RESULTS: Data were obtained from 888 individuals with arthritis. The five domains were sufficiently unidimensional for an IRT-based analysis. Thirty-one items were deleted due to lack of fit or differential item functioning. Daily Activities had the narrowest range for the item location parameter (-2.24 to 0.55) and Handling Objects had the widest range (-1.70 to 2.27). The mean (median) slope parameter for the items ranged from 1.15 (1.07) in Feelings to 1.73 (1.75) in Walking. The final item banks are comprised of 31-45 items each. CONCLUSION: We have developed IRT-based item banks to measure HRQL in 5 domains relevant to arthritis. The items in the final item banks provide adequate psychometric information for a wide range of functional levels in each domain.