Development and testing of the inventory of functional status--chronic pain

Gender differences have been identified in daily activities and the importance of specific activities. Functional status instruments do not reflect these differences and may provide a biased measurement. The purpose of this 3-phase study was to develop a reliable and valid instrument for measuring functional status in women with chronic pain. The Inventory of Functional Status--Chronic Pain (IFS-CP) measures activities primarily engaged in by women and omits from scoring those activities in which the individual does not usually participate. Content validity was established at 91.5%. Reliability and further validity testing in a sample of 204 women with chronic pain found that internal consistency ranged from 0.61 to 0.94 for item to subscale, and from 0.71 to 0.89 for subscale to total scores. Test-retest reliability was 0.93. Testing of construct validity resulted in significant correlations between functional status and pain severity, pain interference [Multiphasic Pain Inventory (MPI)], perception of pain disability [Pain and Impairment Relationship Scale (PAIRS)], and quality of life (QOL, Survey). The IFS-CP provides a means of comprehensively assessing the effects of pain on the functional status of women.