Table 3

Comparison of survival and neurodevelopmental outcomes at 3 years of age for periods 1 and 2 before 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 in 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%
Survived and evaluated6318324177214308376447
 Cerebral palsy‡ §97/61115.9%74/7779.5%**10/4124.4%10/7513.3%44/20621.4%28/2879.8%**43/36411.8%36/4158.7%
 Visual impairments¶ §80/58913.6%31/7024.4%**4/3710.8%9/6214.5%33/20116.4%10/2673.7%**43/35112.3%12/3733.2%**
 Hearing impairments§14/5422.6%6/6251.0%*0/340.0%0/450.0%7/1883.7%3/2401.3%7/3202.2%3/3400.9%
 Cognitive impairments§181/49636.5%278/73337.9%14/3145.2%32/7045.7%66/16041.3%117/26843.7%101/30533.1%129/39532.7%
 DQ of KSPD<70†† §126/38432.8%250/67037.3%11/2642.3%31/6944.9%43/12235.2%99/24540.4%72/23630.5%120/35633.7%
 Delay by physicians‡ ‡ §55/11249.1%28/6344.4%3/560.0%1/1100%23/3860.5%18/2378.3%29/6942.0%9/3923.0%
 NDI: full evaluation§ § §122/30939.4%185/47239.1%10/2245.5%20/3754.1%37/9538.9%77/18541.6%75/19239.0%88/25035.2%
 NDI: incomplete evaluation¶¶ §147/32245.7%137/36038.1%9/1947.4%20/4050.0%72/11960.5%53/12343.0%**66/18435.9%64/19732.4%
  • *P<0.05, **P<0.01, between periods 1 and 2.

  • †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.

  • ‡Cerebral palsy with GMFCS ≥2.

  • §% of each impairment represents the proportion of impairments in measurements. Unadjusted comparisons between the two periods were performed among the evaluated infants for each impairment.

  • ¶Blindness with no functional vision in at least one eye or bilateral amblyopia able to respond to light or hand movement regardless of the use of glasses.

  • †† DQ of KSPD, developmental quotient assessed using the Kyoto Scale of Psychological Development test.

  • ‡‡Delay by physicians represents developmental delays in infants whose DQ were not measured by KSPD judged by paediatricians based on the assessment protocol whether infants were able to speak their own name, age and two-word sentences, build up six blocks, and distinguish between circles with diameters of 4 and 6 cm.

  • §§NDIs were defined as any of the following: cerebral palsy, hearing impairments, visual impairments or DQ of KSPD <70 among infants with full evaluations with KSPD tests.

  • ¶¶NDIs were defined as any of the following: cerebral palsy, hearing impairments, visual impairments, DQ of KSPD <70 or delay by physicians among infants not fully evaluated.

  • DQ, developmental quotient; GMFCS, Gross Motor Function Classification System; KSPD, Kyoto Scale of Psychological Development; NDI, neurodevelopmental impairment; NICU, neonatal intensive care unit.