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Improved outcome into the 1990s for infants weighing 500-999 g at birth. The Victorian Infant Collaborative Study
Insights
Survival rates for extremely low birthweight (ELBW) infants have significantly improved since the 1970s. However, sensorineural disabilities remain higher in ELBW survivors compared to normal birthweight infants.
Area of Science:
- Neonatalogy
- Pediatric Outcomes
- Public Health
Background:
- Extremely low birthweight (ELBW) infants (500-999 g) face significant survival and disability challenges.
- Tracking outcomes for ELBW infants over time is crucial for evaluating medical advancements.
Purpose of the Study:
- To compare survival and sensorineural disability rates in ELBW infants across different birth cohorts (1979-80, 1985-7, 1991-2).
- To compare ELBW infant outcomes with those of normal birthweight infants.
Main Methods:
- Retrospective cohort study comparing ELBW infants born in Victoria across three time periods.
- Inclusion of contemporaneous normal birthweight controls for outcome comparison.
- Analysis of survival to 2 years and rates of severe sensorineural disability.
Main Results:
- Survival rates for ELBW infants significantly increased from 25.4% in 1979-80 to 56.2% in 1991-2.
- Severe disability rates in ELBW survivors decreased from 12.4% in 1979-80 to 6.8% in 1991-2.
- Despite improvements, ELBW infants in 1991-2 had higher disability rates than normal birthweight controls.
Conclusions:
- Survival rates for ELBW infants in Victoria have shown progressive improvement.
- Sensorineural outcomes for ELBW survivors improved between 1979-80 and 1985-7.
- Further reductions in sensorineural disabilities for ELBW infants have not been observed into the 1990s, with rates remaining higher than in normal birthweight infants.
Aims:
To compare the survival and sensorineural disability rates in extremely low birthweight (ELBW) (500-999 g) infants born in 1991-2 with ELBW babies born in 1979-80 and 1985-7, and with normal birthweight infants born in the same time periods.
Methods:
ELBW infants born in Victoria in 1991-2 were compared with regional cohorts of ELBW infants born in 1979-80 and 1985-7, and with contemporaneous normal birthweight (> 2499 g) controls, and those of birthweight 500-749 g with those of birthweight 750-999 g.
Results:
In 1979-80, 25.4% (89/351) ELBW live births survived to 2 years of age, increasing significantly to 37.9% (212/560) in 1985-7, and to 56.2% (241/429) in 1991-2. The rates of severe disability in survivors assessed were 12.4%, 6.6%, and 6.8% in the 1979-80, 1985-7, and 1991-2 ELBW cohorts, respectively. The rate of disability, overall, was significantly lower in the 1985-7 and 1991-2 ELBW cohorts compared with the 1979-80 ELBW cohort, but was significantly higher in 1991-2 ELBW infants than normal birthweight controls. Surviving children with birthweights < 750 g had significantly higher rates of sensorineural disability compared with those of birthweight 750-999 g in 1979-80, but not in 1985-7 or 1991-2.
Conclusions:
Survival rates for ELBW babies in Victoria have progressively improved since the late 1970s. Sensorineural outcome for survivors born in 1985-7 has also improved compared with those born in 1979-80. However, there is no evidence that further reductions in adverse sensorineural outcomes into the 1990s, and these, as well as disabilities remain higher in ELBW than in normal birthweight babies.