Changing incidence and outcome of infants with respiratory distress syndrome in the 1990s: a population-based survey

Aim: To evaluate the trends in the incidence, clinical course and outcome of respiratory distress syndrome (RDS) in the newborn in the Oulu University Hospital region in northern Finland. Methods: In the population of 58 990 infants, the incidence rates of RDS specific to gestational age and birthweight in two consecutive periods, 1990–95 and 1996–99, were calculated. Clinical course and other neonatal morbidities were reported. All surviving infants were followed up until 1 y of corrected age. Results: The overall incidence of RDS did not change significantly (8.7/1000 livebirths in 1990–95 vs 7.6 in 1996–99; p= 0.15), but the gestational age‐adjusted incidence decreased between the two consecutive periods (p= 0.005). The frequency of infants with gestational age below 28 wk tended to increase towards the late 1990s, while their RDS incidence remained unchanged. RDS‐related neonatal mortality decreased in parallel with neonatal mortality, accounting for 15% of all neonatal deaths. The duration of oxygen therapy shortened (8.0 vs 5.5 d) and the incidence of pneumothorax decreased (9.7 vs 4.1%), whereas the rate of chronic lung disease at 36 wk of postconceptional age (16.4 vs 16.7%) and at 1 y of corrected age (9.2 vs 8.2%) remained unchanged, as did also associated neurosensory morbidity (8.8 vs 9.5%). Conclusion: During the 1990s, the incidence of RDS shifted towards more immature infants and the gestational‐age specific incidence decreased. The course of the disease shortened and acute complications decreased. The frequency of chronic pulmonary sequelae (and associated neurosensory morbidity) at the age of 1 y did not change significantly.