Korean J Pediatr 2010;53(6):694-700 • DOI: 10.3345/kjp.2010.53.6.694 699 normal cranial ultrasound have CP or low cognitive performance at 18 months of corrected age16). In our study, similarly, approximately 35.3% of patients affected by BPD showed good prognosis and 36.5% of patients unaffected by BPD showed poor outcomes such as death or neurological developmental impairment. This is because most ELBW infants have not only one morbidity but several neonatal morbidities in the same period8). Schmidt et al.7) therefore made attempts to predict long term outcomes by the combination of 3 neonatal morbidities (severe BPD, severe brain injury and severe ROP). They showed that 3 neonatal morbidities are individually or collectively correlated with poor outcomes such as late death or survival with CP, delayed development, hearing loss, and blindness at 18 months of corrected age. More specifically, in infants who were free of severe BPD, brain injury and ROP, the rate of poor long term outcome was 18% and corresponding rates with any 1, any 2, and all neonatal morbidities were 42%, 62% and 88%, respectively. This shows that the higher the morbidity count, the higher the risk of poor outcome. A simple count of 3 neonatal morbidities strongly predicts the risk of later death or neurosensory impairment. Therefore they established a simple logistic model that predicts poor outcome by using morbidity count. After this, Bassler et al.8) reported the mediated effects of neonatal infection on this logistic model. Neonatal infection is also significantly associated with poor outcomes such as late death or survival with neurosensory impairment. However, infection was a weaker predictor of poor outcome than BPD, brain injury, and severe ROP. When any type of infection was added to the 3 morbidity-count model suggested by Schmidt et al., the rates of poor prognosis were further increased. More specifically, in the sepsis group, the rate of poor long term outcome in infants who were free of severe BPD, brain injury, and ROP was 18% and corresponding rates with any 1, any 2 and all neonatal morbidities were 50%, 68% and 100%, respectively8). Related studies have yet to be reported in Korea. Our study was conducted to see if the morbidity count model of Schmidt et al.7) could be applied to ELBW infants hospitalized at the Severance NICU. Additionally, we added severe PNAC to this model based on recent reports that undernutrition during brain growth is associated with neurodevelopmental deficits as we thought that severe PNAC may reflect undernutrition18, 19). Latal-Hajnal et al.18) have demonstrated that postnatal growth pattern, not being small for gestational age (SGA) at birth, is significantly associated with poor neurodevelopmental outcome at 24 months of corrected age. SGA infants who underwent insufficient catch-up growth and appropriate for gestational age (AGA) infants who underwent catch-down growth had significantly poorer mental and motor function than SGA infants who underwent substantial catch-up growth and AGA infants whose weight remained appropriate for age from birth to 24 months. The most recent reviews note that glutathione, ascorbic acid (vitamin C), riboflavin (vitamin B2) and tocopherol (vitamin E) deficiency during brain growth may induce brain injury secondary to oxidative stress and free radicals. These nutrients are major components of the body’s antioxidant system19). Our study confirms previous reports that severe BPD, severe brain injury, and severe ROP increase the risk of poor outcome in ELBW infants. Severe PNAC was significantly associated with poor outcome in univariate analysis, but was not significantly associated with poor outcome in multiple logistic regression analysis performed to eliminate the effect of the 3 other neonatal morbidities. In our study, in infants who were free of severe BPD, brain injury, ROP and PNAC, the rate of poor outcomes was 9%. Corresponding rates with any 1, any 2 and more than 3 neonatal morbidities were 46%, 69% and 100%, respectively. It also was found that higher morbidity counts were associated with greater risk of poor outcome. Compared with infants with no morbidity, infants with 1 morbidity have approximately double the risk of poor outcome, while 2 morbidities approximately triple the risk. This implies that 4 morbidities would have a similar effect on long term outcome. In infants who were not affected by any one of these 4 mor- bidities, the rate of poor prognosis was 9% in our study (18% was shown in the study of Schmidt et al.). According to our definition, this portion may include infants affected by less than severe BPD, brain injury, ROP, or PNAC or neonatal infection and sepsis which are closely associated with poor outcome. The significance of this study is the predictability of poor outcome for ELBW infants from measurement of simple morbidity count. Moreover, even the smallest and most immature infants have a favorable long term outcome if they survive the NICU stay without serious adverse events and morbidities such as BPD or ROP. In this study, we were not able to establish a logistic morbidity model due to the small cohort size. However, in terms of baseline characteristics, the incidences were comparable to other studies23, 24). In the future, the morbidity count model needs to be proven to be practical by a prospective randomized large scale cohort study. It may then become a useful tool for medical teams planning long term treatment and parent counseling for ELBW infants. References 1) Kim KS, Bae CW. Trends in survival rate for very low birth weight