Objective:

The Social Security Administration (SSA) of the Department of Health and Human Services requested that the Agency for Healthcare Research and Quality (AHRQ), through its Evidence-based Practice Center (EPC) program, produce an evidence report to determine whether specific factors or combination of factors alone or in addition to birth weight predict significant developmental disability in former premature infants and whether premature infants with such factors have long-term developmental disabilities.

Search Strategy:

Studies with original data used in this evidence report were identified through MEDLINE® searches of the English language literature published between 1966 and January 2002. Additional studies were identified from supplemental searches in ERIC, PsycInfo, HealthStar and Embase and from reference lists, review and primary articles, and from domain experts.

Selection Criteria:

We reviewed retrospective and prospective studies reporting impairments in infants or children who weighed 2,000 grams or less, whose gestational age was 35 week or less, or whose birth weight or gestational age were below these thresholds. Preferences were given to recent studies and studies with a minimum of 6 months of follow-up.

Data Collection and Analysis:

We incorporated 178 English language articles in the evidence report. Relevant data from each article were abstracted into evidence tables. Information from the evidence tables was synthesized into summary tables describing the findings of each study. Studies were graded according to the methodological quality and applicability.

Main Results:

We looked for evidence of association of very low birth weight (VLBW defined as <1500 grams) with six outcome conditions. The evidence of the literature overwhelmingly supports that the risk of cerebral palsy (CP) and major neurologic disability is increased among VLBW infants compared to full-term infants. The literature is consistent in demonstrating that risk of CP, major neurosensory and/or neurologic disability is inversely proportional to the degree of immaturity whether measured by gestational age or by birth weight.

The evidence demonstrates that children who were born VLBW have significantly higher rates of cognitive abnormality in early childhood and a several-fold increased prevalence of IQ <70 as adults compared with children or adults who were born normal birth weight at term. There is evidence that even children who were apparently “well” VLBW infants during their neonatal course are also at significantly greater risk for both moderate and severe delay compared to larger birth weight groups.

VLBW infants are at high risk for developing cognitive, neuromotor, and neurosensory disabilities including blindness and hearing loss. These disabilities in turn may lead to other disabilities in speech and language, behavior problems and learning disabilities affecting school performance. All of the above problems have been identified in disproportionate numbers in the VLBW infants.

The studies provided strong evidence of increased incidence of speech and language delays in VLBW and extremely premature infants, and identified clinical factors associated with the increased incidence. Across all measures of short-term memory and language outcomes, preschool children who were born preterm performed at a lower level than children who were full-term counterparts. These deficits were independent of the general IQ.

The evidence identified by this review clearly demonstrates that children born as VLBW infants, with or without retinopathy of prematurity (ROP), are at significantly increased risk of visual impairments and disability compared to children born full term. The risk of visual disability in VLBW infants varies inversely with gestational age.

The studies reviewed indicate that VLBW infants with bronchopulmonary dysplasia (BPD) are at increased risk for long-term pulmonary disability. The greater the severity of BPD, the greater is the association with long-term pulmonary impairment and need for re-hospitalization.

VLBW infants, with or without other conditions, are at high risk for poor growth during the first years of life due to acute neonatal illnesses, developmental delays, and chronic illnesses.

Conclusions:

Surviving premature infants often sustain multi-organ system complications that may persist beyond the first few years of life and frequently result in permanent impairments. Complications of even a single organ system may have a profound impact upon other organ systems. Biomedical determinants of disability in premature infants are often compounded by adverse determinants of social and psychological adaptation of these vulnerable children and their families.