Page 169 - Demo

Development and validation of the TSC-PROM1676have been considered valid and reliable instruments and commonly used in TSC research51-54.Statistical analysesStructural validity, which is the degree to which the scores of the TSC-PROM are an adequate reflection of the dimensionality of the construct to be measured, was assessed for the subscales 1) physical functions, 2) mental functions, and 3) activities and participation. A confirmatory factor analysis (CFA) for each subscale with weighted least square mean- and varianceadjusted (WLSMV) estimator was performed to assess unidimensionality using the R-package “lavaan (v0.6-3)”55,56. We used the following criteria for an acceptable CFA fit: Scaled Comparative Fit Index (CFI) and Tucker-Lewis Index (TLI) values>0.95, a standardized root mean square residual (SRMR) value <0.10, and a root mean square error of approximation (RMSEA) value <0.0857. If CFA fit did not meet the criteria56, a bi-factor model was fit to assess whether unidimensionality was sufficient by assessing if the hierarchical omega (ωh) was >0.80 and the explained common variance (ECV) >0.6058. Local independence was assessed by the residual correlation in the CFA model. An item pair was considered to be locally independent if the residual correlation was <0.2056. Monotonicity was considered sufficient when the item H values of all items were ≥0.30 and the H value of the entire scale was ≥ 0.50, using Mokken scaling59.With regard to internal consistency, which refers to the degree of interrelatedness between items, Cronbach’s alpha was calculated for each TSC-PROM subscale including the continuous HRQoL VAS. A Cronbach’s alpha between 0.70 and 0.95 was considered adequate. Construct validity, which refers to the assessment of the construct we aimed to assess, was examined by correlating the scores of the TSC-PROM with scores of other instruments that assess the same construct to be measured. Convergent validity is a subtype of construct validity and refers to the degree to which measures that theoretically should be related are in fact related. Regarding convergent validity, correlations were assessed between the TSC-PROM domain scores and the SF-36 physical component score, mental component score and the total scores of the ASR, CBCL/1.5-Annelieke Muller sHL.indd 167 14-11-2023 09:07