The development and psychometric testing of an instrument to measure functional status in women with chronic pain

Functional status is an important outcome measure for patients with chronic pain. Functional status measures generally focus on physical impairment or inability to participate in activities. However, many pain syndromes do not have symptoms that lend themselves to direct measurement of impairment. Measures of activity level assume equality of activity importance regardless of gender. Considering the differences in the societal roles of men and women, instruments developed based on this assumption may provide inaccurate data. No instrument is available that measures functional status among patients with chronic pain from a gender-specific perspective. The purpose of this study was to develop a reliable and valid instrument for measuring the functional status of women with chronic pain. The Inventory of Functional Status - Chronic Pain (IFS-CP) is a 57 item instrument with seven subscales measuring the frequency that pain affected women\u27s participation in household, social and community, childcare, care of parents or dependent family members, personal care, work, or educational activities during the previous two weeks. A not applicable code, which is excluded from score calculation, is used for items not usually engaged in by a woman. Content validity was established at 91.5%. Internal consistency reliability used a sample of 204 women with chronic pain. Internal consistency reliability using average correlations for item to subscale correlations ranged from 0.61 to 0.94. Subscale to total IFS-CP correlations ranged from 0.71 to 0.89. Test-retest reliability over a 24 hour interval ranged from 0.75 to 0.91 for subscales and 0.92 for the total, in a subsample of 81 women not currently receiving new treatment modalities. Construct validity was accomplished by examination of subscale correlations, the relationship between pain and functional status, and by the testing of two hypotheses. The number of days of severe pain in the last two weeks was significantly correlated with functional status. As predicted, women who perceived themselves to be more disabled by their pain had significantly lower functional status, and those women with lower functional status had significantly lower quality of life scores. The study\u27s findings revealed content validity, internal consistency, test-retest reliability, and construct validity