Development of an item bank and computer adaptive test for role functioning

Abstract

Role functioning (RF) is a key component of health and well-being and an important outcome in health research. The aim of this study was to develop an item bank to measure impact of health on role functioning. A set of different instruments including 75 newly developed items asking about the impact of health on role functioning was completed by 2,500 participants. Established item response theory methods were used to develop an item bank based on the generalized partial credit model. Comparison of group mean bank scores of participants with different self-reported general health status and chronic conditions was used to test the external validity of the bank. After excluding items that did not meet established requirements, the final item bank consisted of a total of 64 items covering three areas of role functioning (family, social, and occupational). Slopes in the bank ranged between .93 and 4.37; the mean threshold range was -1.09 to -2.25. Item bank-based scores were significantly different for participants with and without chronic conditions and with different levels of self-reported general health. An item bank assessing health impact on RF across three content areas has been successfully developed. The bank can be used for development of short forms or computerized adaptive tests to be applied in the assessment of role functioning as one of the common denominators across applications of generic health assessment.