Background data, incidence of retinopathy of prematurity (ROP) and frequency of treatment in the study population of infants with gestational age (GA) ≤30 weeks
| Year | 2008 n=698 | 2009 n=693 | 2010 n=655 | 2011 n=706 | 2012 n=725 | 2013 n=714 | 2014 n=762 | 2015 n=772 | 2016 n=787 | 2017 n=737 | Total n=7249 |
| GA (w) * | 28.4 (22.3:30.6) | 28.3 (22.4:30.6) | 28.4 (22.5:30.6) | 28.3 (22.2:30.6) | 28.4 (22.0:30.6) | 28.2 (22.1:30.6) | 28.3 (22.4:30.6) | 28.3 (21.6:30.6) | 28.3 (21.6:30.6) | 28.5 (22.3:30.6) | 28.3 (21.6:30.6) |
| GA (w) | |||||||||||
| 21 | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (0.1) | 1 (0.1) | 0 (0.0) | 2 (0.0) |
| 22 | 7 (1.0) | 4 (0.6) | 3 (0.5) | 8 (1.1) | 8 (1.1) | 8 (1.1) | 9 (1.2) | 11 (1.4) | 10 (1.3) | 17 (2.3) | 85 (1.2) |
| 23 | 21 (3.0) | 24 (3.5) | 20 (3.1) | 18 (2.5) | 24 (3.3) | 29 (4.1) | 32 (4.2) | 33 (4.3) | 35 (4.4) | 24 (3.3) | 260 (3.6) |
| 24 | 27 (3.9) | 46 (6.6) | 37 (5.6) | 53 (7.5) | 27 (3.7) | 31 (4.3) | 40 (5.2) | 59 (7.6) | 59 (7.5) | 50 (6.8) | 429 (5.9) |
| 25 | 52 (7.4) | 63 (9.1) | 54 (8.2) | 47 (6.7) | 67 (9.2) | 55 (7.7) | 65 (8.5) | 69 (8.9) | 65 (8.3) | 52 (7.1) | 589 (8.1) |
| 26 | 66 (9.5) | 77 (11.1) | 91 (13.9) | 57 (8.1) | 75 (10.3) | 104 (14.6) | 73 (9.6) | 82 (10.6) | 86 (10.9) | 63 (8.5) | 774 (10.7) |
| 27 | 103 (14.8) | 91 (13.1) | 72 (11.0) | 104 (14.7) | 91 (12.6) | 93 (13.0) | 112 (14.7) | 69 (8.9) | 78 (9.9) | 78 (10.6) | 891 (12.3) |
| 28 | 118 (16.9) | 93 (13.4) | 103 (15.7) | 126 (17.8) | 110 (15.2) | 114 (16.0) | 116 (15.2) | 127 (16.5) | 118 (15.0) | 109 (14.8) | 1134 (15.6) |
| 29 | 127 (18.2) | 135 (19.5) | 137 (20.9) | 137 (19.4) | 130 (17.9) | 138 (19.3) | 142 (18.6) | 149 (19.3) | 142 (18.0) | 167 (22.7) | 1404 (19.4) |
| 30 | 177 (25.4) | 160 (23.1) | 138 (21.1) | 156 (22.1) | 193 (26.6) | 142 (19.9) | 173 (22.7) | 172 (22.3) | 193 (24.5) | 177 (24.0) | 1681 (23.2) |
| BW (g) * | 1135.0 (307:2356) | 1100.0 (400:2220) | 1103.0 (420:1947) | 1120.0 (382:2090) | 1135.0 (340:2842) | 1067.5 (415:1975) | 1090.0 (387:2364) | 1094.0 (415:2445) | 1115.0 (348:3245) | 1140.0 (390:2405) | 1109.5 (307:3245) |
| Single/multiple, n (%) | |||||||||||
| 1 | 526 (75.4) | 518 (74.7) | 480 (73.3) | 509 (72.1) | 587 (81.0) | 556 (77.9) | 537 (70.5) | 572 (74.1) | 590 (75.0) | 551 (74.8) | 5426 (74.9) |
| 2 | 172 (24.6) | 175 (25.3) | 175 (26.7) | 197 (27.9) | 138 (19.0) | 158 (22.1) | 225 (29.5) | 200 (25.9) | 197 (25.0) | 186 (25.2) | 1823 (25.1) |
| Female gender, n (%) | 305 (43.7) | 299 (43.1) | 318 (48.5) | 340 (48.2) | 345 (47.6) | 336 (47.1) | 323 (42.4) | 329 (42.6) | 362 (46.0) | 341 (46.3) | 3298 (45.5) |
| ROP level, n (%) | |||||||||||
| 0 | 511 (73.2) | 451 (65.1) | 451 (68.9) | 496 (70.3) | 509 (70.2) | 481 (67.4) | 509 (66.8) | 487 (63.1) | 515 (65.4) | 529 (71.8) | 4939 (68.1) |
| 1–2 | 120 (17.2) | 157 (22.7) | 111 (16.9) | 147 (20.8) | 164 (22.6) | 160 (22.4) | 166 (21.8) | 185 (24.0) | 164 (20.8) | 126 (17.1) | 1500 (20.7) |
| 3 | 65 (9.3) | 80 (11.5) | 90 (13.7) | 62 (8.8) | 51 (7.0) | 70 (9.8) | 85 (11.2) | 94 (12.2) | 104 (13.2) | 79 (10.7) | 780 (10.8) |
| 4–5 | 2 (0.3) | 5 (0.7) | 3 (0.5) | 1 (0.1) | 1 (0.1) | 3 (0.4) | 2 (0.3) | 6 (0.8) | 4 (0.5) | 3 (0.4) | 30 (0.4) |
| Treated ROP, n (%) | 36 (5.2) | 43 (6.2) | 45 (6.9) | 31 (4.4) | 30 (4.1) | 40 (5.6) | 45 (5.9) | 60 (7.8) | 60 (7.6) | 50 (6.8) | 440 (6.1) |
*Mean and median are given for gestational age and birth weight.
BW, birth weight; g, grams; GA, gestational age; w, week.