1 = Conservative
2 = Aggressive
3 = dropout conservative
4 = dropout aggressive

1 = Conservative Screening
2 = Aggressive Screening

0 = no
1 = yes

1 = regular discharge or Transfer >37+0
2 = Transfer <37+0
3 = dead
4 = transfer < 28d

0 = missing
9999 = dead

999 = missing
9999 = dead

1 = complete course
2 = incomplete course
3 = none

0 = Single infant
2 = twin
3 = triplet

99 = intubated
999 = missing

0 = none
1 = one episode
2 = two episodes
3 = three episodes

0 = no IVH or IVH grade 1-2
1 = severe IVH (grade 3 or 4)

any surgery
0 = nein
1 = ja

0 = no
1 = Yes

0 = No
1 = Yes

0 = no ROP
1 = Stage1
2 = Stage 2
3 = Stage3
4 = Stage4
9 = not examined

9999 = missing

9999 = fehlend

0 = low
1 = high

999 = missing
9999 = tot

0 = no (>-1)
1 = mild (-1 bis -2)
2 = severe (< -2)

0 = no
1 = mild (-1 bis -2
2 = severe (< -2)

0 = none
1 = mild (-1 bis -2)
2 = severe (< -2)

8888 = excluded due to CMV

8888 = CMV

0 = no
1 = yes
8888 = CMV
9999 = dead

8888 = CMV
9999 = tot

Group = 2 (FILTER)
0 = Not Selected
1 = Selected

0 = no (>-1)
1 = yes