Measuring functional disability in children with developmental disorders in low-resource settings: validation of Developmental Disorders-Children Disability Assessment Schedule (DD-CDAS) in rural Pakistan

Abstract

Background: Developmental disorders (DDs) in children are a priority condition and guidelines have been developed for their management within low-resource community settings. However, a key obstacle is lack of open access, reliable and valid tools that lay health workers can use to evaluate the impact of such programmes on child outcomes. We adapted and validated the World Health Organization's Disability Assessment Schedule for children (WHODAS-Child), a lay health worker-administered functioning-related tool, for children with DDs in Pakistan.

Methods: Lay health workers administered a version of the WHODAS-Child to parents of children with DDs (N = 400) and without DDs (N = 400), aged 2-12 years, after it was adapted using qualitative study. Factor analysis, validity, reliability and sensitivity to change analyses were conducted to evaluate the psychometric properties of the adapted outcome measure.

Results: Among 800 children, 58% of children were male [mean (s.d.) age 6.68 (s.d. = 2.89)]. Confirmatory Factor Analysis showed a robust factor structure [χ²/df 2.86, RMSEA 0.068 (90% CI 0.064-0.073); Tucker-Lewis Index (TLI) 0.92; Comparative Fit Index (CFI) 0.93; Incremental Fit Index (IFI) 0.93]. The tool demonstrated high internal consistency (α 0.82-0.94), test-retest [Intra-class Correlation Coefficient (ICC) 0.71-0.98] and inter-data collector (ICC 0.97-0.99) reliabilities; good criterion (r -0.71), convergent (r -0.35 to 0.71) and discriminative [M (s.d.) 52.00 (s.d. = 21.97) v. 2.14 (s.d. = 4.00); 95% CI -52.05 to -47.67] validities; and adequate sensitivity to change over time (ES 0.19-0.23).

Conclusions: The lay health worker administrated version of adapted WHODAS-Child is a reliable, valid and sensitive-to-change measure of functional disability in children aged 2-12 years with DDs in rural community settings of Pakistan.

Keywords: AMOS, Analysis of Moment Structure; Autism; CFA, Confirmatory Factor Analysis; CFI, Comparative Fit Index; CGAS, Children-Global Assessment of Functioning; DD-CDAS, Developmental Disorders-Children Disability Assessment Schedule; DD-CGAS, Developmental Disorders Children-Global Assessment of Functioning; Developmental Disabilities Children's Global Assessment Scale (DD-CGAS); Developmental Disorders-Children Disability Assessment Schedule (DD-CDAS); ICC, Interclass Correlation; ICF, International Classification of Functioning; ICF-CY, International Classification of Functioning-Children and Youth; IFI, Incremental Fit Index; International Classification of Functioning-Children and Youth (ICF-CY); LHWs, Lady Health Workers.; RMSEA, Root Mean Square Error of Approximation; SDGs, Sustainable Development Goals; TLI, Tucker–Lewis Index; TQS, Ten Questions Screen; VABS, Vineland Adaptive Behavior Scales; WHO Disability Assessment Schedule (WHODAS 2.0); WHO mhGAP, World Health Organization Mental Health Gap Action Programme; childhood disability; developmental disorders/disabilities; functional disability; intellectual disability; low-resource settings; non-specialists.

Fig. 1.

Developmental Disorders-Children Disability Assessment Schedule (DD-CDAS) domain profile by sub-group (N=400) (N = 800).

Fig. 2.

Distribution curve for ‘global disability score’ of DD-CDAS for children with and without developmental disorders (N = 800).

Fig. 3.

First-order Confirmatory Factor Analysis of the Developmental Disorders-Children Disability Assessment Schedule (DD-CDAS).

Fig. 4.

Second-order Confirmatory Factor Analysis of Developmental Disorders-Children Disability Assessment Schedule (DD-CDAS).

Fig. 5.

DD-CDAS domain profile by sub-group (N = 400).