Adapting the Ages and Stages Questionnaire to Identify and Quantify Development Among Children With Evidence of Zika Infection

Abstract

This article describes novel methods of applying the Ages and Stages Questionnaire-3rd edition (ASQ-3) to assess and quantify developmental delay among children following the 2015-2016 Zika virus outbreak in Brazil. Many of the children with Zika virus infection were expected to have severe developmental delay. However, administering the ASQ-3 to caregivers of these children according to standard protocol would have screened for the overall presence of delay but not the severity of delay. We adopted an amended protocol for administration of the ASQ-3 to quantify the developmental functioning of children severely affected by Zika virus infection in this investigation. Protocols for administering the ASQ-3 among this population were drafted in consultation with developmental measurement experts and are presented here. Specific developmental estimates are discussed, including developmental age equivalents, developmental quotients, and developmental quotient z scores. The calculations of these estimates are presented with examples in the context of the 2015-2016 Zika virus outbreak and associated microcephaly among prenatally infected children from 2 states in northeastern Brazil. Potential applications of these methods for estimating developmental ability among similar pediatric populations are discussed.

Keywords: Ages and Stages Questionnaire; Zika virus; child development; developmental screening; microcephaly; neurotropic infection; quantitative methods.

Figure 1.

Standard and amended ASQ-3 administration protocol flowchart. Standard protocol available from Squires et al. (2009), ASQ-3 User’s Guide. The “first two items” referenced in the amended protocol represent developmental abilities 2 SDs below average for children of the same age as the given questionnaire. Thus, if a child cannot perform these abilities, his or her functioning is below average and the 4-month questionnaire is appropriate. ASQ-3 = Ages and Stages Questionnaire—3rd edition.

Figure 2.

ASQ distribution and percent delay estimates. Y-axis represents the percentage of children in the ASQ-3 normative population with a score between each SD range (unpublished figure courtesy of Jane Squires). ASQ = Ages and Stages Questionnaire.

Figure 3.

Density plots of developmental quotient z scores by ASQ-3 domain among children with microcephaly (n = 50) and without microcephaly (n = 100). Black line at x = −2 represents the threshold value for at risk for delay and gray line at x = −1 represents the threshold for monitoring for delay. DQ = developmental quotient.