Reliability and minimal detectable change of the Challenge, an advanced motor skills test for children with cerebral palsy, Danish version

Purpose

To translate and cross-culturally adapt the Challenge, and investigate the reliability and minimal detectable change (MDC) of the Danish Challenge in children with cerebral palsy (CP).

Materials and methods

A Danish version of the Challenge was created through a standardized translation process. Four physiotherapists evaluated face validity. Independently ambulatory children with CP were tested.

Live performance rating was conducted by assessors independently scoring the Challenge. Video-rating was undertaken for a subset of assessments. Same day assessment test–retest reliability was estimated. The Challenge’s Best Score Total was of primary interest.

Results

Forty-five children (5–18 years: mean 10 years 9 months; 19 girls) in Gross Motor Function Classification System levels I and II were tested. Inter-rater reliability was excellent for live assessments (n?=?45) ICC = 0.998 (95% CI 0.998–0.999) and video assessments (n?=?15) ICC = 0.991 (95% CI 0.963–0.997) and intra-rater reliability was excellent for live versus video-recorded assessments (n?=?10) ICC = 0.977 (95% CI 0.895–0.994).

Test–retest reliability (n?=?22) was excellent with ICC = 0.991 (95% CI 0.979–0.996) and minimal detectable change (MDC90) of 4.7 points.

Conclusions

The Danish Challenge showed excellent reliability in this testing context when physiotherapists scored from live- or video-recorded assessments. The Challenge’s ability to detect 4.7 points change seems a clinically realistic target for progress.