Background: Infants born preterm are at increased risk of developing cognitive and motor impairments compared with infants born at term. Early developmental interventions have been used in the clinical setting with the aim of improving the overall functional outcome for these infants. However, the benefit of these programs remains unclear.
Objectives: To review the effectiveness of early developmental intervention post-discharge from hospital for preterm (< 37 weeks) infants on motor or cognitive development.
Search strategy: The Cochrane Neonatal Review group search strategy was used to identify randomised and quasi-randomised controlled trials of early developmental interventions post hospital discharge. Two review authors independently searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE Advanced, CINAHL, PsychINFO and EMBASE (1966 through February 2006).
Selection criteria: Studies included had to be randomised or quasi-randomised controlled trials of early developmental intervention programs that commenced within the first 12 months of life for infants born at < 37 weeks with no major congenital abnormalities. Intervention could commence as an inpatient; however, a post discharge component was necessary to be included in this review. The outcome measures were not pre-specified other than that they had to assess cognitive and/or motor ability. The rates of intellectual impairment, cerebral palsy and development co-ordination disorder were also documented.
Data collection and analysis: Data were extracted and entered by two independent review authors. Cognitive and motor outcomes were pooled in three age groups - infant (0 to 2 years), preschool (3 to < 5 years) or school age (5 to 17 years). Meta-analysis was carried out using RevMan 4.2 to determine the effects of early developmental intervention in the short (0 to 2 years), medium (3 to < 5 years) and long term (5 to 17 years). Subgroup analysis was carried out in relation to; gestational age, birthweight, brain injury, commencement of intervention, focus of intervention and study quality.
Main results: Sixteen studies met the inclusion criteria (2379 randomised patients). Six of these studies were RCTs and had strong methodological quality. There was variability with regard to the focus and intensity of the intervention, and in length of follow-up. Meta-analysis concluded that intervention improved cognitive outcomes at infant age (developmental quotient [DQ]: standard mean difference [SMD] 0.46 SD; 95% CI 0.36 0.57; P < 0.0001), and at preschool age (intelligence quotient [IQ]; SMD 0.46 SD; 95%CI 0.33, 0.59; P < 0.0001). However, this effect was not sustained at school age (IQ; SMD 0.02 SD; 95% CI -0.10, 0.14; P = 0.71). There was significant heterogeneity between studies for cognitive outcomes at infant and school ages. There was little evidence of an effect of early intervention on motor outcomes in the short, medium or long-term, but there were only two studies reporting outcomes beyond 2 years.
Authors' conclusions: Early intervention programs for preterm infants have a positive influence on cognitive outcomes in the short to medium term. However, there was significant heterogeneity between the interventions included in this review. Further research is needed to determine which early developmental interventions are the most effective at improving cognitive and motor outcomes, and on the longer-term effects of these programs. Cost-effectiveness and access to services should also be evaluated since they are important factors when considering implementation of an early developmental intervention program for a preterm infant.