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

Abstract

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. This retrospective cohort study included preterm infants with ELBW (≤1000g). 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. 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 NICUs. 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. 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 patients from these vulnerable populations to appropriate care settings.