Table 1

Infants' characteristics at birth, first sign of ROP and ROP treatment

Model development group
(N=6991)
Validation groups
(N=1241)
P value*
Girls3158 (45.2%)607 (48.9%)0.016
GA at birth (weeks)28.3 (1.9)
28.6 (24.0; 30.9)
28.0 (1.9)
28.3 (24.0; 30.9)
<0.0001
GA (full weeks)0.0007
 24427 (6.1%)94 (7.6%)
 25597 (8.5%)114 (9.2%)
 26781 (11.2%)129 (10.4%)
 27914 (13.1%)187 (15.1%)
 281141 (16.3%)239 (19.3%)
 291419 (20.3%)236 (19.0%)
 301712 (24.5%)242 (19.5%)
Birth weight (grams)1146 (339)
1135 (307; 3245)
1068 (319)
1065 (335; 2450)
<0.0001
Birth weight SDS (Niklasson and Albertsson-Wikland 2008)−1.03 (1.37)
−0.77 (−8.56; 4.93)
−1.31 (1.57)
−0.99 (−9.92; 2.75)
<0.0001
Birth year<0.0001
 2006–2007543 (7.8%)139 (11.2%)
 2008–20091331 (19.0%)119 (9.6%)
 2010–20111303 (18.6%)9 (0.7%)
 2012–20131369 (19.6%)103 (8.3%)
 2014–20151445 (20.7%)249 (20.1%)
 2016–20171000 (14.3%)331 (26.7%)
 2018–20190 (0.0%)291 (23.4%)
Any ROP2026 (29.0%)502 (40.5%)<0.0001
PNA at first diagnosed ROP (weeks)8.35 (2.22)
8.14 (3.43; 18.71)
8.07 (2.56)
7.71 (3.14; 19.00)
ROP treatment287 (4.1%)49 (3.9%)0.87
PNA at ROP treatment (weeks)12.8 (2.8)
12.4 (7.0; 21.9)
12.3 (2.4)
11.9 (7.1; 19.6)
  • Model development group includes data from Swedish National Registry for ROP, born at GA 24–30 weeks (2007–2017).

  • Validation groups consist of four external validation cohorts, one from Sweden (later time period than in the model development group), one from Germany and two from USA.

  • For categorical variables, n (%) is presented. For continuous variables, mean (SD)/median (min; max) is given.

  • *P values should be interpreted with caution due to the large cohorts. Conclusions should be made based on the clinically relevant differences.

  • GA, gestational age; PNA, postnatal age; ROP, retinopathy of prematurity; ROP, retinopathy of prematurity; SDS, standard deviation score.