A population-based language-screening programme started in the western part of Sweden (South Bohuslän) in 1991, with the aim of identifying developmental language disability in 2.5-y-old children. The programme was evaluated during 1998 in an experimental study. A group of 105 2.5-y-old children was recruited from 24 separate Child Health Centres. A sample of 25 children with a positive screening result was selected. For each of the 25 children, 1-4 controls, i.e. children with a negative screening result, were selected. The results were reclassified blindly by three speech and language therapists and used as a gold standard. Positive and negative predictive values were estimated to be 0.52 (95% confidence interval 0.31-0.72) and 0.96 (95% confidence interval 0.89-0.99), respectively. Baye's theorem was used to calculate the sensitivity (0.69) and the specificity (0.93) of the screening. A method of calculating the sensitivity and specificity of the test method by means of three samples was demonstrated.
Conclusion: The data confirm that it is possible to identify reliably children with developmental language disability at 2.5 y of age through the screening programme.