Measuring mobility limitations in children with cerebral palsy: development, scalability, unidimensionality, and internal consistency of the mobility questionnaire, MobQues47.

OBJECTIVES

To develop a questionnaire that specifically and comprehensively measures mobility limitations in children with cerebral palsy (CP) and to investigate certain psychometric properties (scalability, unidimensionality, internal consistency) of this questionnaire.

DESIGN

Cross-sectional study.

SETTING

Private physical therapy practices and outpatient departments of hospitals and rehabilitation centers.

PARTICIPANTS

Children with CP undergoing physical therapy or rehabilitation. The Mobility Questionnaire, 47-item (MobQues47), was completed by the mothers of these children (N=323; mean age +/- SD, 7.1+/-2.9y; 57% boys; Gross Motor Function Classification levels: I [48%], II [26%], III [19%], IV [7%]).

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: Mokken scale analysis was used to investigate (1) scalability, indicating that the items form a scale; (2) unidimensionality, indicating that the items measure only 1 concept; and (3) internal consistency, indicating the degree of interrelatedness of the items.

RESULTS

The MobQues47, made up of 47 items, was developed on the basis of 3 pilot studies and careful operationalization of the concept (or construct) of mobility limitations. The scalability (coefficient H=.70), unidimensionality, and internal consistency (coefficient rho=.99) of the MobQues47 were found to be very good.

CONCLUSIONS

The MobQues47 is a unidimensional scale with excellent internal consistency that can be used to measure caregiver-reported mobility limitations in children with CP.