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.