The Pain Impact Inventory-Further Validation in Various Subgroups.

Objectives: The aim of the study was to further psychometrically evaluate the instrument "Pain Impact Inventory" (PII) in various subgroups. Methods: The sample comprised 384 persons (aged between 18 and 102 years) who reported chronic pain. The instrument PII was evaluated in terms of construct validity as well as reliability. The instrument's validity was investigated through corrected item-total correlation, floor and ceiling effects, and item response rate. Reliability was assessed by means of test-retest (with a 2-week interval) and Cronbach's alpha. All analyses were performed in various subgroups, men and women, as well as in 6 different age-groups and 5 primary pain location. Results: The result showed an item-total correlation above 0.30 for all items in all subgroups with exception for the 2 items in F5 in the age-group, 30 to 44. In the test-retest analysis, all kappa coefficients in the test-retest analysis were significant (P < 0.001) and varied between 0.482 and 0.879. The alpha values for factor 1 to 4 ranged between 0.80 and 0.94. Alpha values below 0.7 were only found for F5. Conclusion: The PII showed satisfactory psychometric properties in terms of construct validity and reliability with regard to gender, age-groups, and primary pain location.