The effect of patient volume on mortality and morbidity of extremely low birth weight infants in Taiwan

Background: To assess whether the number of extremely low birth weight (ELBW) infants treated annually in neonatal intensive care units (NICUs) in Taiwan affects the mortality and morbidity of this patient population.Methods: This retrospective cohort study included preterm infants with ELBW (<= 1000 g). NICUs were divided into three subgroups according to the annual admissions of ELBW infants (low, <= 10; medium, 11-25; and high, >25). Perinatal characteristics, mortality, and short-term morbidities were compared between groups.Results: A total of 1945 ELBW infants from 17 NICUs were analyzed (low-volume, n = 263; medium-volume, n = 420; and high-volume, n = 1262). After risk adjustments, infants from NICUs with low patient volumes were at a higher risk of death. The risk-adjusted odds ratios (aOR) for mortality were 0.61 (95% CI, 0.43-0.86) in the high-volume NICUs and 0.65 (95% CI, 0.43-0.98) in medium-volume NICUs, compared with infants admitted to low-volume NI -CUs. Infants in medium-volume NICUs had the lowest incidence of prenatal steroid exposure (58.1%, P < 0.001) and were associated with the highest risk of necrotizing enterocolitis (aOR, 2.35 [95% CI, 1.48-3.72 ]), severe intraventricular hemorrhage (aOR, 1.55 [95% CI, 1.01-2.28]), and bronchopulmonary dysplasia (aOR, 1.61 [95% CI, 1.10-2.35]). However, survival without major morbidity did not differ between the groups.Conclusion: The mortality risk was higher among ELBW infants admitted to NICUs with a low annual patient volume. This may emphasize the importance of systematically referring pa-tients from these vulnerable populations to appropriate care settings.