Objective: To analyze the structure of a combination of physical items from the Functional Independence Measure (FIM) and seven instrumental activity items using ratings of dependence and perceived difficulty.
Design: Disability in terms of dependence and subject's perceived difficulty was studied in patients with cerebral palsy (CP) and spina bifida (SB). Rasch analysis was used to construct calibrated linear measure and to identify suitable models with respect to rating steps.
Setting: Interviews were performed at home with patients from an outpatient university rehabilitation unit for young disabled persons.
Patients: Fifty-three CP and 20 SB patients (including 5 with other early acquired spinal cord lesions), 20 to 39 years of age, participated and represented 62% and 80%, respectively, of available patients. All had fulfilled an elementary school program.
Results: The best scoring model using Rasch analysis was achieved using 5 levels for dependence and 4 levels for perceived difficulty. Hierarchic orders for all items are presented. The FIM items Bowel and Bladder showed different characteristics in the two groups of patients, especially for perceived difficulty, and were excluded in the joint calibrations. There was close overall agreement between the ratings of dependence and perceived difficulty. Person measure values from the Rasch analyses were separated between wheelchair users and walkers.
Conclusion: The combination of physical items from FIM and instrumental activity measure (IAM) are useful for disability assessment in community-living persons and should be further studied in other impairment groups.