The natural history of speech impairment of 8-year-old children in the Avon Longitudinal Study of Parents and Children: Error rates at 2 and 5 years

This prospective longitudinal population study observed the speech of 741 children at the ages of 2, 5 and 8 years. At the age of 8, 132 children were categorized as speech impaired. There was strong evidence of differences between the case and control groups in speech sound error rate at the two earlier age points. The pattern of the proportion of errors was similar for cases and controls. There was evidence of a strong relationship between the child's error rate and expressive language at age 2 and between the child's error rate and sentence length at age 5. In multivariable analyses, adjusting for expressive language, parent's social status, maternal age, gender and child's exact age, the increase in odds of being a case as the proportion of errors increased disappeared at 2 years but remained at 5 years. At 5 years, the proportion of speech errors was predictive of ongoing speech errors at the age of 8 years; the adjusted odds of having speech errors at 8 years increased by between 21 and 44% with every 10% rise in the proportion of errors in the target patterns.