Ethnic Variation in the Incidence and Severity of Retinopathy of Prematurity: Possible Explanations, Including Racial Differences in Illness Severity

Retinopathy of prematurity in Korean infants with birthweight greater than 1500 g

OBJECTIVE

To determine the incidence and clinical features of, and risk factors for, retinopathy of prematurity (ROP) in Korean infants with birthweight (BW) >1500 g.

METHODS

A total of 201 consecutive infants with BW >1500 g from January 2009 to December 2013 were included. The location and maximal stage of retinopathy observed were recorded for each infant. The associated systemic and maternal risk factors in infants with mild or absent ROP were compared with those in infants with treatment-requiring ROP.

RESULTS

The total incidence of ROP was 11.94% and that of treatment-requiring ROP was 3.98%. Two patients with gestational age (GA) >32 weeks and BW >1500 g had treatment-requiring ROP. 15 eyes from eight infants with type I ROP required laser photocoagulation. The mean BWs and GAs in the treatment-requiring ROP group were significantly lower than those in the no or mild ROP group. Total duration of oxygen supplementation, surfactant usage, respiratory distress syndrome, bronchopulmonary dysplasia, antibiotic use for more than 14 days and the number of ROP-associated risk factors significantly increased the likelihood of treatment-requiring ROP (p=0.002, p=0.008, p=0.008, p=0.000, p=0.015, and p=0.004, respectively).

CONCLUSION

Our study confirmed that treatment-requiring ROP does occur in infants with BW >1500 g. To avoid overlooking infants with vision-threatening ROP, an evaluation of the data from larger BW preterm infants is advisable so that screening guidelines in neonatal care units may be refined.

Cumulative illness severity and progression from moderate to severe retinopathy of prematurity

OBJECTIVE

To test cumulative neonatal illness severity (IS) and IS fluctuation as predictors of progression from moderate to severe retinopathy of prematurity (ROP).

METHODS

Data from research databases and medical record review were collected for infants from four neonatal intensive care unit (NICUs) admitted between 1995 and 2001 and diagnosed with prethreshold ROP. Cumulative neonatal IS measured using daily Scores for Neonatal Acute Physiology (SNAP) for the first 28 days of life, and IS fluctuation as assessed by summing changes between daily SNAP scores, were tested as predictors of progression to threshold ROP using logistic regression.

RESULTS

Infants progressing to threshold (n=79), compared to those not progressing to threshold (n=130), had significantly (P<0.05) lower gestational ages (25.2+/-1.1 versus 25.8+/-1.4 weeks), higher cumulative neonatal SNAP (255+/-77 versus 224+/-63 weeks) and had more severe hospitalizations as indicated by diagnoses and medical management. In regression analysis, gestational age, chronological age and presence of plus disease at first diagnosis of prethreshold were associated with development of threshold. After adjusting for these factors, cumulative neonatal SNAP was significantly associated with progression to threshold. However, addition of cumulative SNAP to the model only increased receiver-operating characteristic curve area from 0.77 to 0.78 (NS). Other factors, including SNAP fluctuation, were not associated with progression to threshold after adjustment using this model.

CONCLUSIONS

Cumulative neonatal IS, as measured by cumulative SNAP, is an independent risk factor for progression from moderate to severe ROP. However, cumulative IS does not enhance assessment of risk for ROP progression after adjusting for simpler clinical factors.