The validity and reliability of the impact on participation and autonomy questionnaire

Background: This study evaluated the validity and reliability of a new measure: Impact on Participation and Autonomy Questionnaire, English Version (IPA-E). The IPA has shown to load onto five factors. Method: Two hundred and thirteen people with multiple sclerosis, rheumatoid arthrites spinal cord injury and GP attendees were recruited and stratified by level of disability (median age 54). Inclusion criteria: English as first language, aged 18-75, score> 6 on Mental Status Questionnaire. A sample size calculation was conducted. Sixty-six Participants completed the IPA-E on a second occasion. Other measures: SF-36, London Handicap Scale, three domains of the Functional Limitations Profile (household management, social integration, emotion).Results: Confirmatory Factor Analysis confirmed the construct validity of the IPA-E normal fit index (NFI) = 0.98, (comparative fit index (CFI) = 0.99), indicating a good fit to the model. Convergent and discriminant validity was confirmed by the predicted associations, or lack of, with the exception of a poor association between the 'social life/relationships' IPAE subscale and 'FLP-emotion'. Internal reliability of the IPA was confirmed (Cronbach alphas > 0.8and item-total correlations for all subscales > 0.5). Test-retest reliability was confirmed for all but one item (weighted kappas > 0.6) and subscales (ICCs > 0.90).Discussion: Further research is required to examine the responsiveness of the IPA to change over time, its clinical utility and suitability for use with people from ethnic minorities and with older people.Conclusion. The IPA is a valid, reliable and acceptable measure of participation and autonomy in people with a range of conditions and can make a unique and fundamental contribution to outcome assessment