Survival rates in extremely low birthweight infants depend on the denominator: avoiding potential for bias by specifying denominators
ABSTRACT The objective of the study was to assess whether recent data reporting survival of preterm infants introduce a bias from the use of varying denominators.
We performed a systematic review of hospital survival of infants less than 1000 g or less than 28 weeks. Included publications specified the denominator used to calculate survival rates.
Of 111 eligible publications only 51 (46%) specified the denominators used to calculate survival rates: 6 used all births, 25 used live births, and 20 used neonatal intensive care unit admissions. Overall rates of survival to hospital discharge ranged widely: from 26.5% to 87.8%. Mean survival varied significantly by denominator: 45.0% (±11.6) using a denominator of all births, 60.7% (±13.2) using live births, or 71.6% (±12.1) using used neonatal intensive care unit admissions (P ≤ .009 or less for each of 3 comparisons).
Variations in reported rates of survival to discharge for extremely low-birthweight (<1000 g) and extremely low-gestational-age (<28 weeks) infants reflect in part a denominator bias that dramatically affects reported data.
[Show abstract] [Hide abstract]
ABSTRACT: We compare two ways to control the distribution function of ions on the isolated structure which is treated in a plasma reactor based on beam plasma discharge. In the first case, the periodic pulse voltage is applied to the substrate holder. The calculation of currents and voltages on the surface in contact with the plasma in a simple empirical model has been performed; the comparison of results of calculation and experiment is presented. In the latter case, the pulsed voltage is applied to the discharge collector, thus modulating the plasma potential. The comparison shows that the second method provides more efficient control of the distribution function of ions, acting on the treated substrate.Vacuum 01/2011; 85(6):711-717. DOI:10.1016/j.vacuum.2010.11.004 · 1.43 Impact Factor
08/2013; 167(10). DOI:10.1001/jamapediatrics.2013.2758
[Show abstract] [Hide abstract]
ABSTRACT: Objective: To evaluate the maternal and perinatal outcomes of pregnancies delivered at 23+0 to 23+6 weeks’ gestation. Methods: This prospective cohort study included women in the Canadian Perinatal Network who were admitted to one of 16 Canadian tertiary perinatal units between August 1, 2005, and March 31, 2011, and who delivered at 23+0 to 23+6 weeks’ gestation. Women were included in the network if they were admitted with spontaneous preterm labour with contractions, a short cervix without contractions, prolapsing membranes with membranes at or beyond the external os or a dilated cervix, preterm premature rupture of membranes, intrauterine growth restriction, gestational hypertension, or antepartum hemorrhage. Maternal outcomes included Caesarean section, placental abruption, and serious complication. Perinatal outcomes were mortality and serious morbidity. Results: A total of 248 women and 287 infants were included in the study. The rate of Caesarean section was 10.5% (26/248) and 40.3% of women (100/248) had a serious complication, the most common being chorioamnionitis (38.6%), followed by blood transfusion (4.5%). Of infants with known outcomes, perinatal mortality was 89.9% (223/248) (stillbirth 23.3% [67/287] and neonatal death 62.9% [156/248]). Of live born neonates with known outcomes (n = 181), 38.1% (69/181) were admitted to NICU. Of those admitted to NICU, neonatal death occurred in 63.8% (44/69). Among survivors at discharge, the rate of severe brain injury was 44.0% (11/25), of retinopathy of prematurity 58.3% (14/24), and of any serious neonatal morbidity 100% (25/25). Two subgroup analyses were performed: in one, antepartum stillbirths were excluded, and in the other only centres that indicated they offered fetal monitoring at 23 weeks’ gestation were included and antepartum stillbirths were excluded. In each of these, perinatal outcomes similar to the overall group were found. Conclusion: Pregnant women delivering at 23 weeks’ gestation are at risk of morbidity. Their infants have high rates of serious morbidity and mortality. Further research is needed to identify strategies and forms of management that not only increase perinatal survival but also reduce morbidities in these extremely low gestational age infants and reduce maternal morbidity.Journal of obstetrics and gynaecology Canada: JOGC = Journal d'obstetrique et gynecologie du Canada: JOGC 03/2015; 37(3):214-24.