These authors contributed equally to this study as co-first authors.
Korea currently has the world’s lowest birth rate but a rapidly inreasing number of preterm infants. The Korean Neonatal Network (KNN), launched by the Korean Society of Neonatology under the support of Korea Centers for Disease Control, has collected population-based data for very low birth weight infants (VLBWIs) born in Korea since 2013. In terms of the short-term outcomes of VLBWIs born from 2013 to 2016 registered in the KNN, the survival rate of all VLBWIs was 86%. Respiratory distress syndrome and bronchopulmonary dysplasia were observed in 78% and 30% of all VLBWIs, respectively. Necrotizing enterocolitis occurred in 7%, while 8% of the VLBWIs needed therapy for retinopathy of prematurity in the neonatal intensive care unit (NICU). Sepsis occurred in 21% during their NICU stay. Intraventricular hemorrhage (grade ≥III) was diagnosed in 10%. In terms of the long-term outcomes for VLBWIs born from 2013 to 2014 registered in the KNN, the post-discharge mortality rate was approximately 1.2%–1.5%, mainly owing to their underlying illness. Nearly half of the VLBWIs were readmitted to the hospital at least once in their first 1–2 years of life, mostly as a result of respiratory diseases. The overall prevalence of cerebral palsy was 6.2%–6.6% in Korea. Bilateral blindness was reported in 0.2%–0.3% of VLBWIs, while bilateral hearing loss was found in 0.8%–1.9%. Since its establishment, the KNN has published annual reports and papers that facilitate the improvement of VLBWI outcome and the formulation of essential healthcare policies in Korea.
The Korean Neonatal Network (KNN) has collected population-based data for very low birth weight infants (VLBWIs) born in Korea since 2013. The survival rate of all VLBWIs was 86% in Korea. The overall prevalence of cerebral palsy was 6.2%–6.6%. Bilateral blindness and hearing loss were reported in 0.2%–0.3%, 0.8%–1.9%, respectively. The KNN has published annual reports and papers for facilitating the improvement of VLBWIs outcome in Korea.
In recent years, Korea has encountered 2 major health issues related to perinatal and neonatal care. The first issue is an extremely low overall birth rate (0.977 in 2018), the lowest recorded rate worldwide. The annual number of newborns in Korea was approximately 326,900 in 2018, which is approximately a 50% reduction from 720,000 at 20 years ago, which creates difficulty preparing for the national driving force of the future [
Among premature infants, approximately 2,500 very low birth weight infants (VLBWIs; birth weight <1.5 kg) requiring neonatal intensive care are born every year. This is more than a 2fold increase from approximately 1,000 from 20 years ago [
The Korean Neonatal Network (KNN) was launched on April 15, 2013 by the Korean Society of Neonatology under the support of the Korea Centers for Disease Control (KCDC). The KNN is composed of a webbased registry of VLBWIs through voluntary participation of hospitals nationwide. Registration servers and data storage are securely maintained at the KCDC. This provides the basis for facilitating multicenter clinical studies to collect national epidemiological data on VLBWIs and improve their prognosis [
At present, 70 hospitals among nearly 100 neonatal intensive care units (NICUs) nationwide (
The KNN provides an annual overview adjusting for the prevalence and mortality rates in each institution compared to all the other participating hospitals, which helps compare and study the level and direction of treatment for VLBWIs for each institution; consequently, this provides an important basis upon which to improve treatment quality. As such, the KNN provides the basis for quality improvement (QI) by providing feedback for each institution based on strict refinement of data and statistical analysis, selecting the benchmarking index and applying program development. The goal of expanding the application of the QI program of the KNN is to improve neonatal intensive care quality nationwide [
The KNN has also been conducting various clinical studies with numerous subjects based on the accumulated information on VLBWIs in Korea related to both morbidity and mortality. The KNN has published approximately 20 international peer-reviewed journal papers to date and is still actively publishing highquality papers, which plays an important role in the academic development of neonatology in Korea.
Moreover, the KNN is educating the public and raising awareness on treatment results, perception, longterm followup, and healthcare for VLBWIs by publishing an annual report for the general public as part of the annual reports published. By informing the public that VLBWIs require continued healthcare through followup at medical institutions for a certain period after NICU discharge, the reports play a significant facilitating role in helping them adapt and be cared for as healthy Korean citizens. These KNN activities can contribute to the establishment of proper health care policies for highrisk newborns while providing necessary data through government interactions in the future.
Furthermore, the KNN plans to join the International Network for Evaluation of Outcomes of Neonates (iNeo), an international network collecting data on VLBWIs in 11 countries and 10 new born networks. By joining the iNeo, the KNN is expected to actively promote QI on a national level based on objectified international data and a comparative analysis of factors such as morbidity and mortality rates among countries.
As such, the KNN plays an important role in Korean neonatology and neonatal health; it can help formulate future plans that are crucial in addressing the extremely low fertility rate, thereby achieving continuous national support.
Preterm birth and the resulting complications are the leading causes of mortality in children younger than 5 years [
The KNN recently reported the findings of a population-based study conducted in Korea to evaluate the survival rates and significant morbidities of VLBWIs [
Despite improvements in the neonatal outcomes of VLBWIs, the survival and morbidity rates of more immature infants with a GA of 22–27 weeks remain to be improved in Korea. Therefore, it is necessary to develop treatment strategies to improve the neonatal outcomes of VLBWIs in Korea.
To evaluate the longterm outcomes, we reviewed registry data from the KNN collected for VLBWIs born between January 2013 and December 2014 in Korea [
The mean GA and birth weight were 291/7±26/7 weeks and 1,093±268 g in 2013 and 292/7±26/7 weeks and 1,125±261 g in 2014, respectively. The postdischarge mortality rate was approximately 1.2%–1.5%, mainly owing to underlying illness. The infants at the <50th percentile for height and head circumference accounted for more than half of the population of this study. Approximately half of the VLBWIs were readmitted to the hospital at least once in their first 1–2 years of life, mostly as a result of respiratory illnesses. Further, surgery for underlying health issues such as inguinal hernia required readmission in the first 1–2 years of life. The rate of the need for oxygen after discharge was 14%–17% (
The followup rate for the Bayley Scale Infant Development Second Edition (BSIDII) was low, probably because milder cases that were not referred to rehabilitation facilities may have been excluded. Only 631 infants (23.7%) were assessed. Of them, 55 (22.4%) in 2013 and 45 (24.1%) in 2014 were at risk based on their mental developmental index (scores <70); further, 63 (25.6 %) in 2013 and 27 (14.4%) in 2014 were at risk based on their psychomotor developmental index. For the BSIDIII, the follow-up rate was even lower; therein, 198 infants (7.4 %) were enrolled. Of them, 6 (7.8%) in 2013 and 5 (4.1%) in 2014 were at risk of cognitive developmental impairment; 5 (6.5%) in 2013 and 7 (5.8%) in 2014 for language developmental impairment; and 10 (13%) in 2013 and 4 (3.4%) in 2014 for motor developmental impairment among the VLBWIs at the corrected 18 months of age (
Currently, the KNN is following up these VLBWIs for longer periods, which may provide information on additional and clearer relationships with longterm outcomes. In the future, it will be necessary to observe minor neurodevelopmental sequelae such as cognitive deficits, academic underachievement [
Since its establishment in 2013, the KNN has been collecting data of VLBWIs in Korea and publishing annual reports and papers that provide an essential basis for QI and various clinical studies. Through these activities, the KNN helps facilitate improved outcomes of VLBWIs in Korea and provides necessary data for formulating future essential healthcare policies for newborns and premature infants.
Therefore, the KNN should be maintained and further developed to create populationbased datadriven appropriate healthcare policies for highrisk infants. Furthermore, it can facilitate active neonatal multicenter research studies and QI for neonatal intensive care, ultimately leading to improved prognosis of highrisk newborns, including very preterm infants. Consequently, evidencebased neonatal medicine that can reduce healthcare costs may be developed in Korea.
No potential conflict of interest relevant to this article was reported.
This research was supported by a fund (2016-ER6307-02#) by Research of Korea Centers for Disease Control and Prevention.
National distribution of 70 neonatal intensive care units participating in the Korean Neonatal Network. Available from:
Cerebral palsy cases by gestational age among very low birth weight infants born in 2013. Adapted from the Executive Committee of Korean Neonatal Network. 2013 Korean Neonatal Network Annual Report: Korean Centers for Disease Control and Prevention, 2014 [
Cerebral palsy cases by gestational age among very low birth weight infants born in 2014. Adapted from the Executive Committee of Korean Neonatal Network. 2014 Korean Neonatal Network Annual Report: Korean Centers for Disease Control and Prevention, 2015 [
Demographic data of very low birth weight infants of Korean Neonatal Network, 2013–2016
Gestational age (wk) | 22–23 (n=372) | 24–25 (n=1,156) | 26–27 (n=1,644) | 28–29 (n=2,191) | 30–32 (n=2,078) | >32 (n=828) | Total (n=8,269) |
---|---|---|---|---|---|---|---|
Male | 52 (47–58) | 52 (49–55) | 53 (50–55) | 51 (49–53) | 47 (45–50) | 47 (44–50) | 50 (49–51) |
Multiple birth | 39 (34–44) | 34 (31–36) | 29 (27–31) | 34 (32–36) | 41 (39–43) | 38 (35–42) | 35 (34–36) |
Maternal age <20 yr | 0 (0–2) | 1 (0–1) | 0 (0–1) | 0 (0–1) | 0 (0–1) | 0 (0–1) | 0 (0–1) |
Maternal age >35 yr | 30 (26–35) | 32 (30–35) | 36 (34–38) | 32 (31–35) | 34 (32–36) | 35 (32–39) | 34 (33–35) |
Antenatal steroid | 63 (58–68) | 79 (76–81) | 82 (80–84) | 81 (79–83) | 80 (79–82) | 45 (42–49) | 76 (75–77) |
Cesarean section | 49 (43–54) | 71 (68–74) | 74 (71–76) | 77 (75–79) | 85 (83–86) | 88 (86–90) | 77 (76–78) |
Maternal diabetes | 2 (1–4) | 5 (4–6) | 9 (8–10) | 10 (9–12) | 10 (9–11) | 8 (6–10) | 8 (8–9) |
Maternal hypertension | 3 (2–6) | 8 (7–10) | 13 (12–15) | 17 (15–18) | 33 (31–35) | 38 (34–41) | 21 (20–21) |
Values are presented as percentage (range of probability: 95% confidence interval).
There is a significant difference among groups if the probability ranges do not overlap with each other.
Modified from Lee et al. J Korean Med Sci 2019;34:e40 [
Neonatal outcomes of very low birth weight infants of Korean Neonatal Network, 2013–2016
Gestational age (wk) | 22–23 (n=372) | 24–25 (n=1,156) | 26–27 (n=1,644) | 28–29 (n=2,191) | 30–32 (n=2,078) | >32 (n=828) | Total (n=8,269) |
---|---|---|---|---|---|---|---|
Survival rate | 33 (28–38) | 65 (62–67) | 84 (82–85) | 94 (93–95) | 97 (96–98) | 98 (97–99) | 86 (85 87) |
Respiratory distress syndrome | 98 (95–99) | 98 (97–99) | 96 (95–97) | 89 (88–91) | 60 (58–62) | 21 (18–23) | 78 (77 79) |
BPD | 88 (80–93) | 64 (61–68) | 47 (44–49) | 26 (24–28) | 14 (13–16) | 5 (4–7) | 30 (29 31) |
ROP Tx. | 20 (16–25) | 25 (23 28) | 11 (9–12) | 3 (2–4) | 1 (0–1) | 0 (0–1) | 8 (7 8) |
NEC≥IIa | 20 (16–25) | 15 (13–17) | 9 (8–11) | 4 (3–5) | 3 (2–3) | 2 (1–4) | 7 (6 7) |
Sepsis | 38 (33–43) | 36 (33–39) | 31 (29–33) | 18 (16–19) | 11 (9 –12) | 6 (4–8) | 21 (20 22) |
Drug for PDA | 39 (34–45) | 52 (49–55) | 48 (45–50) | 34 (32–36) | 21 (19–23) | 9 (7–11) | 34 (33 35) |
Ligation of PDA | 18 (14–23) | 25 (23–28) | 18 (16–20) | 7 (6–9) | 3 (3–4) | 2 (1–3) | 11 (10 12) |
IVH (≥grade III) | 45 (39–51) | 27 (25–30) | 12 (11–14) | 5 (4–6) | 2 (1–3) | 1 (0–2) | 10 (9 10) |
PVL | 15 (11–20) | 12 (10–15) | 11 (9–12) | 8 (7–9) | 5 (4–6) | 2 (1–3) | 8 (7 9) |
Values are presented as percentage (range of probability: 95% confidence interval).
There is a significant difference among groups if the probability ranges do not overlap with each other.
Modified from Lee et al. J Korean Med Sci 2019;34:e40 [
Clinical characteristics and outcomes of very low birth weight infants (n=2,660)
Variable | 2013 (n=1,000) | 2014 (n=1,660) |
---|---|---|
Gestational age (wk) | 291/7±26/7 | 292/7±26/7 |
Birth weight (g) | 1,093±268 | 1,125±261 |
Male | 504 (50.4) | 833 (50.2) |
Post-discharge mortality | 15 (1.5) | 20 (1.2) |
Respiratory | 5 (45.5) | 6 (35.3) |
Underlying disease | 11 (73.3) | 17 (85.0) |
Growth at visit | ||
Weight | n=800 | n=1,091 |
<50th | 465 (46.5) | 721 (66.1) |
50th–90th | 243 (30.4) | 337 (30.9) |
Height | n=753 | n=993 |
<50th | 482 (64.0) | 622 (62.6) |
50th–90th | 219 (29.1) | 325 (32.7) |
Head circumference | n=632 | n=811 |
<50th | 404 (64.0) | 516 (63.6) |
50th–90th | 176 (27.8) | 267 (32.9) |
Rehospitalizations |
n=846 | n=1,182 |
Respiratory | 262 (44.9) | 349 (47.5) |
Surgery | 135 (23.2) | 168 (22.8) |
Infection | 106 (18.2) | 106 (14.4) |
Medical treatment |
n=846 | n=1,182 |
Oxygen | 142 (16.8) | 166 (14.0) |
Ventilator | 53 (6.3) | 60 (5.1) |
Nasogastric tube feeding | 76 (9.0) | 100 (8.5) |
Cerebral palsy | n=846 | n=1,182 |
Diplegia | 28 (3.3) | 46 (3.9) |
Hemiplegia | 4 (0.5) | 7 (0.6) |
Quadriplegia | 24 (2.8) | 20 (1.7) |
Unknown | 21 (2.5) | 47 (4.0) |
Rehabilitative support | ||
No | 512 (60.5) | 748 (63.2) |
Yes | 318 (37.6) | 412 (34.9) |
Language support | ||
No | 779 (92.1) | 1081 (91.5) |
Yes | 43 (5.1) | 68 (5.7) |
Eye and hearing | n=846 | n=1,182 |
Blindness | n=846 | n=1,134 |
One-eye | 4 (0.5) | 3 (0.3) |
Both eyes | 2 (0.2) | 3 (0.3) |
Ophthalmologic disorders |
120 (14.2) | 179 (15.1) |
Retinopathy of prematurity | 56 (41.2) | 51 (26.6) |
Glaucoma | 0 | 3 (1.6) |
Cataract | 2 (1.5) | 1 (0.5) |
Strabismus | 29 (21.3) | 40 (20.8) |
Refraction abnormality | 15 (11.0) | 11 (5.7) |
Wearing glasses | 23 (2.7) | 19 (1.6) |
Hearing impairment |
24 (3.2) | 22 (1.9) |
Unilateral | 10 (1.3) | 12 (1.0) |
Bilateral | 14 (1.9) | 10 (0.8) |
Hearing aid | 6 (0.7) | 3 (0.3) |
Need for cochlear impairment | 1 (0.1) | 4 (0.3) |
Values are presented as mean±standard deviation or number (%).
The above variable was described as multiple answers.
Modified from Youn et al. J Korean Med Sci 2018;33:e309 [
Bayley scales of infant developmental outcomes: VLBWI born in 2013 vs. 2014
Variable | 2013 | 2014 |
---|---|---|
BSID 2nd ed. | 246 | 187 |
MDI | ||
<69 | 55 (22.4) | 45 (24.1) |
70–84 | 64 (26.0) | 46 (24.6) |
85–114 | 109 (44.3) | 84 (44.9) |
≥115 | 18 (7.3) | 12 (6.4) |
PDI | ||
<69 | 63 (25.6) | 27 (14.4) |
70–84 | 58 (23.6) | 40 (21.4) |
85–114 | 114 (46.3) | 107 (57.2) |
≥115 | 11 (4.5) | 13 (7.0) |
BSID 3rd ed. | 77 | 121 |
Cognitive | ||
≤54 | 0 (0) | 0 (0) |
55–69 | 6 (7.8) | 5 (4.1) |
70–84 | 9 (11.7) | 8 (6.6) |
85–114 | 52 (67.5) | 94 (77.7) |
≥115 | 10 (13.0) | 14 (11.6) |
Language | ||
≤54 | 2 (2.6) | 2 (1.7) |
55–69 | 3 (3.9) | 5 (4.1) |
70–84 | 23 (29.9) | 25 (20.7) |
85–114 | 44 (57.1) | 73 (60.3) |
≥115 | 5 (6.5) | 16 (13.2) |
Motor | ||
≤54 | 4 (5.2) | 2 (1.7) |
55–69 | 6 (7.8) | 2 (1.7) |
70–84 | 8 (10.4) | 15 (12.4) |
85–114 | 55 (71.4) | 94 (77.7) |
≥115 | 4 (5.2) | 8 (6.6) |
Values are presented as number (%).
VLBWI, very low birth weight infant; BSID, Bayley Scales of Infant Development; MDI, Mental Developmental Index; PDI, Psychomotor Developmental Index.
Modified from Youn et al. J Korean Med Sci 2018;33:e309 [