Discriminant ability and criterion validity of the Trunk Impairment Scale for cerebral palsy

Abstract

Aims: To compare the performance of children with mild and moderate-to-severe cerebral palsy (CP) on the Trunk Impairment Scale (TIS), Gross Motor Function Measure (GMFM), and on center-of-pressure variables; to establish the discriminant ability of these tools to predict severity of motor impairment in CP; and to investigate the criterion validity of the TIS.

Methods: Children with mild (n = 18, 11 males, 7 females, mean age = 9.5 ± 2.9 years, Gross Motor Function Classification System I–II) and moderate-to-severe (n = 18, 11 males, 7 females, mean age = 9.2 ± 229, Gross Motor Function Classification System III–IV) CP were tested using the TIS and the GMFM, and during static sitting on force-plate.

Results: Children with mild CP showed better trunk (median; 95% confidence interval = 22.5; 21.29–22.59 vs. 13; 11.97–14.8; p < 0.001) and gross motor (60; 57.73–59.3 vs. 40; 38.96–46.25; p < 0.001) scores, and better postural control (lower center of pressure (CoP) displacement [anterior–posterior: (0.42; 0.32–1.11 vs. 0.89; 0.70–1.65; p = 0.022); medial–lateral: (0.42; 0.31–1.08 vs. 0.91; 0.65–1.17; p = 0.044)], and lower area of sway, (0.05; −0.15–0.97 vs. 0.44; 0.23–0.90; p = 0.008) than the moderate-to-severe group. Trunk control and gross motor function explained 81.5% of the variance in the severity of motor condition. Correlations between the TIS and the GMFM were excellent (ρ = 0.944, p < 0.001); correlations between the TIS and CoP variables were low (anterior–posterior displacement: ρ = −0.411, p < 0.05; medial–lateral displacement: ρ = −0.327, p < 0.05); area of sway: ρ = −0.430, p < 0.05; velocity of sway: ρ = −0.308, p < 0.05).

Conclusions: The TIS is able to differentiate levels of trunk control across various levels of motor impairments in CP. It is a valid tool to assess trunk control, showing very high concurrent validity with the GMFM sitting dimension.

Implications for Rehabilitation

• Trunk Impairment Scale (TIS) can be used by rehabilitation professionals to differentiate levels of trunk control across levels of motor impairment.

• TIS showed concurrent validity with Gross Motor Function Measure and should be used to assess trunk control in children with cerebral palsy (CP) in clinical settings.

• The use of TIS allows a reliable assessment of postural control in children with CP in clinical settings.

Keywords:

• Cerebral palsy
• Trunk Impairment Scale
• discriminant ability
• criterion validity
• psychometric properties

Disclosure statement

No potential conflict of interest was reported by the authors.