Table 4

Survival and neurodevelopmental outcomes at 3 years of age for periods 1 and 2 after multiple imputations

Total22 weeks23 weeks24 weeks
Period 1Period 2Period 1Period 2Period 1Period 2Period 1Period 2
n=1479n=1839n=183n=271n=544n=686n=752n = 882
Not admitted to the NICU†171.1%432.3%42.2%269.6%112.0%131.9%20.3%40.5%
Death at the NICU47131.8%41722.7%**11462.3%11943.9%**19836.4%16924.6%**15921.1%12914.6%**
Death after discharge80.5%70.4%10.5%10.4%50.9%40.6%20.3%20.2%
Cerebral palsy§979.9%745.4%**1015.6%108.0%4413.3%285.6%**437.3%364.8%*
Visual impairments§808.1%312.3%**46.3%97.2%3310.0%102.0%**437.3%121.6%**
Hearing impairments§141.4%60.4%*00.0%00.0%72.1%30.6%71.2%30.4%
DQ of KSPD < 70§26126.7%38127.8%2132.8%5543.2%10933.0%15831.6%13122.2%16822.5%
Death or NDI¶79453.7%86246.9%**14177.0%20475.3%33661.8%34650.4%**31742.2%31235.4%**
  • *P<0.05, **P<0.01, unadjusted comparisons between periods using the χ2 or Fisher’s exact test.

  • †Not admitted to the NICU represents live-birth infants who were not admitted to the NICU of the same hospital and died. This category started to be registered from 2006 in period 1.

  • ‡Two infants with missing data on death after NICU discharge in period 2 were estimated as having survived without follow-up data.

  • §% of each impairment represents proportion of infants with impairments among surviving infants. Unadjusted comparisons between the two periods were performed among survivors.

  • ¶NDIs were defined as any of the following: cerebral palsy, hearing impairments, visual impairments or DQ of KSPD <70.

  • DQ, developmental quotient; KSPD, Kyoto Scale of Psychological Development; NDI, neurodevelopmental impairment; NICU, neonatal intensive care unit