If a child aged 12-60 months passes the Ages and Stages Questionnaire (ASQ) in all domains there is a moderate probability that there is no severe developmental delay, a systematic review and meta-analysis has found.

A total of 43 studies that met the inclusion criteria were included in the systematic review. These criteria were: ASQ carried out in children aged 12 to 60 months, or where the median age at ASQ was at least 12 months; and formal comparative developmental assessments i.e. reference tests were performed either two months before or after the ASQ. Of these 43 studies, 36 were included in the meta-analysis.

Two thresholds were used to define failure on the ASQ; scores > 2 SD below the mean (ASQ-2SD) and ASQ scores > 1 SD below the mean (ASQ-1SD) in one or more domain.

For the formal developmental assessments any developmental delay was defined as being > 1 SD below the mean in 1 or more domain with severe developmental delay defined as > 2 SD below the mean.

Each ASQ domain was mapped to the equivalent on the more formal tests.

In the meta-analysis, a positive likelihood ratio (PLR) > 5 and a negative likelihood ratio (NLR) ≤ 0.2 were applied to rule in or rule out developmental delay, respectively, with at least moderate probability.

Any developmental delay

ASQ-2SD to predict any delay in 1 or more domain

• Sensitivity 0.77 (95% CI: 0.64-0.86; I ²  = 94.9%)

• Specificity 0.81 (95% CI: 0.75-0.86; I ²  = 96.6%)

• Diagnostic odds ratio 14.62 (95% CI: 8.3-25.7; I ²  = 100%)

• PLR 4.10 (95% CI: 3.17-5.30; I ²  = 89.8%)

• NLR 0.28 (95% CI: 0.18-0.44; I ²  = 95.3%)

The researchers concluded that if the prevalence of developmental delay is 5%, and a child from that population fails ASQ-2SD, then the post-test probability of having any developmental delay increases to 18%, but if the child passes ASQ-2SD, the post-test probability of having any developmental delay decreases from 5% to 1%.

Severe developmental delay

ASQ-2SD to predict severe developmental delay in 1 or more domain

• Sensitivity 0.84 (95% CI: 0.75-0.90; I²  = 85.3%)

• Specificity 0.77 (95% CI: 0.71-0.82; I ² = 95.8%)

• Diagnostic odds ratio 18.2 (95% CI: 11.1-30.0; I ²  = 100%) 

• PLR 3.72 (moderate) (95% CI: 2.98-4.64; I ² = 92.1%)

• NLR 0.20 (moderate) (95% CI: 0.13-0.32;  I ² = 86.9%)

In these cases, failing the test increases the chance of having severe developmental delay to 16% and passing the test reduces the chance from 5% to 1%.

The study authors conclude: ‘Based on generally accepted interpretation of likelihood ratios, if a child aged 12 to 60 months passes ASQ-2SD in all domains, there is a moderate probability that they do not have severe developmental delay.’

Dr Peter Saul