The objective of this study was to evaluate and compare the construct validity of 5 participation instruments developed using the International Classification of Functioning, Disability and Health (ICF). A total of 545 subjects diagnosed and treated for a spinal condition at an acute hospital were followed-up and consented to complete a questionnaire. Subjects completed 5 participation instruments (Impact on Participation and Autonomy (IPA), Keele Assessment of Participation (KAP), Participation Measure-Post Acute Care (PM-PAC), Participation Objective Participation Subjective (POPS), World Health Organization Disability Assessment Schedule II (WHODAS II)). In addition, each subject completed a health status instrument and a quality of life instrument. The dimensionality, convergent/discriminant validity and known-group validity of the participation instruments were assessed. A confirmatory factor analysis of the facture structure for the IPA and PM-PAC demonstrated adequate model fit. For convergent/discriminant validity, correlations were generally higher among similar domains of the WHODAS II, IPA, KAP and PM-PAC, and as expected the lowest correlations were observed with the objective domains of the POPS. Most instruments demonstrated known-group validity.
Differences in the construct validity evidence of the POPS compared with the other 4 instruments were noted. To date, there is no gold standard for measuring participation, and clinicians and researchers should consider the type of information required prior to selecting an instrument.