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Assisted ventilation and survival of extremely low birthweight infants
L W Doyle1, P Davis, A Dharmalingam
1Department of Obstetrics and Gynaecology, University of Melbourne, Parkville, Victoria, Australia.
Insights
Improving survival rates for extremely low birthweight (ELBW) infants increased ventilator resource consumption. Initial cost-effectiveness worsened, then improved with advances like antenatal steroids and surfactant therapy.
Area of Science:
- Neonatal Medicine
- Perinatal Care
- Health Economics
Background:
- Survival rates for extremely low birthweight (ELBW) infants have improved significantly since the introduction of assisted ventilation.
- The increasing survival rates raise questions about the associated consumption of ventilator resources and cost-effectiveness.
Purpose of the Study:
- To determine the incremental consumption of ventilator resources linked to improved survival rates in ELBW infants.
- To analyze the cost-effectiveness of assisted ventilation for ELBW infants over time.
Main Methods:
- A cohort study of ELBW infants born between 1971 and 1993 in a tertiary perinatal center.
- Analysis of in-hospital survival rates and patient-days of assisted ventilation across distinct eras.
- Calculation of cost-effectiveness ratios (incremental ventilator resources per additional survivor) between eras.
Main Results:
- Survival rates for ELBW infants increased progressively across study eras (6.2% to 68.8%).
- Ventilator resource consumption also rose (0.1 to 24.7 patient-days per livebirth).
- The cost-effectiveness ratio initially deteriorated but improved in later eras, particularly with advances like antenatal steroids and surfactant therapy.
Conclusions:
- The initial rise in resource consumption without proportional survival gains was likely due to increased resource availability.
- Improvements in cost-effectiveness in later eras were associated with advancements in perinatal care, including antenatal steroids and exogenous surfactant.
- The study highlights the evolving economic impact of neonatal intensive care for ELBW infants.
Objective:
To determine the incremental consumption of ventilator resources associated with the improving survival rate of extremely low birthweight (ELBW birthweight 500-999g) infants, from the time assisted ventilation was introduced.
Methodology:
Cohort study of ELBW infants born in one tertiary perinatal centre (The Royal Women's Hospital, Melbourne). All ELBW infants born from 1971 to 1993 were included in the study. In hospital survival rates and patient-days of assisted ventilation were the main outcome measures. Discrete eras of relatively stable survival rate and consumption of ventilator resources were identified. These comprised the years 1971-74, 1977-83, 1985-90, and 1992-93. Cost-effectiveness ratios (the incremental consumption of ventilator resources per additional survivor) were calculated between adjacent eras by dividing the increment in the consumption of ventilator resources by the increment in the survival rate.
Results:
The survival rates rose progressively between eras (6.2, 33.9, 49.1, 68.8%, respectively, as did the consumption of ventilator resources (0.1, 6.6, 16.2, 24.7 patient-days of assisted ventilation per livebirth, respectively). The cost-effectiveness ratio deteriorated initially, increasing from 23.2 to 63.5 additional patient-days of assisted ventilation per additional survivor, but then improved, falling to 43.1 additional patient-days of assisted ventilation per additional survivor in the last era. These changes were even more marked for those of birthweight 750-999g (20.0, 63.2 to 35.9 additional patient-days of assisted ventilation per additional survivor, respectively). In contrast, the cost-effectiveness ratio was initially worse for those of birthweight 500-749 g, being three-fold higher than for the larger infants, and only improved substantially in the last era (59.8, 58.3 to 44.1 additional patient-days of assisted ventilation per additional survivor, respectively).
Conclusions:
The initial deterioration in cost-effectiveness ratios between successive eras probably reflected the increased availability of resources for assisted ventilation, without any other major advances in perinatal care. The improvement in cost-effectiveness in the last era reflected, in part, the increased use of antenatal steroid therapy and the introduction of exogenous surfactant to neonatal intensive care.