Objective: To investigate the appropriate criteria for the screening of retinopathy of prematurity (ROP) in Xi'an region and to determine the risk factors for ROP.
Methods: Screening criteria were established basing on the ROP screening guidelines, implemented by Ministry of Public Health with minor modification. It included newborn infants with birth weight of 2000 g or less, or gestational age of 34 w or less. The results obtained by the present screening criteria were compared with those obtained from the national screening criteria. Gestation age and birth weight between groups of ROP and normal fundus were compared by Student t-test, the ratios of persistent oxygen inhalation were examined by Chi-square test, and the risk factors for ROP were analyzed by Fisher exact test. A P < 0.05 was considered significant.
Results: In all the infants examined, 18 cases (36 eyes, 13.43%) developed ROP, including 4 cases (8 eyes) suffering from stage 1, 5 cases (10 eyes) from stage 2 (one was affected in zone II with plus disease), 5 cases (10 eyes) from stage 3 with plus disease, 1 case (2 eyes) from stage 4 A, 1 case (2 eyes) from stage 5, and 2 cases (4 eyes) from regressed stage. In ROP cases, gestation age ranged from 28 to 34 w, (30.58 +/- 1.97) w; birth weight ranged from 880 to 1950 g, (1388.89 +/- 268.39) g. Statistical analysis showed that, the gestation age and birth weight in normal fundus group were (32.56 +/- 2.00) w and (1773.91 +/- 349.73) g respectively, which were higher than group of ROP (gestation age t = 3.90, P < 0.01; birth weight t = 4.45, P < 0.01). The ratios of persistent oxygen inhalation in group of normal fundus and ROP were 59.48% and 61.11% (chi(2) = 0.017, P > 0.05). It was also observed that the ratios of hypoxic-ischemic encephalopathy and placenta abruption in those two groups were 12.07%, 33.33% (P = 0.030) and 0.86%, 11.11% (P = 0.047). Clinical analysis indicated that prematurity, low birth weight, hypoxic-ischemic encephalopathy and placenta abruption were closely related to the occurrence of ROP. On the other hand, if using national screening criteria, only 108 infants in all 134 cases required screening, and all of the ROP cases could be detected with a detection rate at 16.67%.
Conclusions: The detection rate of ROP is 13.43% (18/134) in the present study, which is consistent with the results obtained in previous studies in China. The national criteria are appropriate for the ROP screening in Xi'an region. Prematurity, low birth weight and the relative hypoxia are high risk factors for the occurrence of ROP.