Measurement properties of the Trunk Impairment Scale-modified Norwegian version among people with mild to moderate multiple sclerosis.

Abstract

The Trunk Impairment Scale-modified Norwegian version (TIS-modNV) measures trunk control for clinical and research purposes. This study examined the validity and reliability of the TIS-modNV in people with multiple sclerosis (pwMS). Sixty-eight pwMS (mild to moderate) participated. The TIS-modNV and the Mini-Balance Evaluation Systems Test (Mini-BESTest) scores were compared for <i>construct validity</i> using Spearman's rho (<i>r_s</i>). TIS-modNV performance was videotaped and rated by four physiotherapists on two occasions. The <i>inter-</i> and <i>intrarater reliability</i> was analyzed via intraclass correlation coefficients (ICC), standard errors of measurement (SEM), Bland-Altman plots, and kappa statistics (<i>k</i>). Validity was demonstrated (<i>r_s</i> = 0.55-0.61). Interrater reliability for the total score was moderate to good (ICC(A,1) =0.67; ICC(C,1) = 0.78), and the SEM was 2 points (12.8%). Interrater reliability varied across the rater pairs (ICC(A,1) = 0.54-0.81) as displayed in the Bland-Altman plots. Item-level interrater agreement varied from poor to good (<i>k</i> = 0.10-0.79). Intrarater reliability of the total scores was moderate to good (ICC(A,1) = 0.67-0.82). This study supports the construct validity and overall reliability of the TIS-modNV in pwMS with mild to moderate disability. However, variations in rater reliability need to be addressed.