Neonatal illness severity and new insights into perinatal audit

The article by Kaaresen in this issue (1) uses the unique assets of Norwegian regional geography, vital statistics and high quality medical records to document the performance of a NICU over 16 y. It is a diligent, methodologically rigorous self-examination that will genuinely benefit their patients. The results are very instructive. 1. The Clinical Risk Index for Babies (CRIB) works very well in yet another population of very low birthweight babies. 2. The accuracy of CRIB has not been affected by the introduction of surfactant. 3. The secular rise in survival coincided with (and is significantly associated with) surfactant. The authors, perhaps out of respect for their obstetric colleagues, do not ram this last point home, but the data cry out for explanation. After 1984 (i) the rate of antenatal corticosteroid administration dropped from 49% to 26% ( p 1⁄4 0:003) and even to 21% thereafter; (ii) pre-NICU deaths jumped from 4% to 15% ( p 1⁄4 0:03); (iii) the percent of very low birthweight newborns requiring resuscitation rose from 25% to 35% ( p 1⁄4 0:13); (iv) of the delivery room survivors, the median CRIB increased significantly (this occurred despite a slightly favourable change in birthweight and gestational distribution, meaning that the physiologic component of CRIB must have gone up substantially); and (v) the NICU survival rate decreased from 73% to 61% (p 1⁄4 0:003) and did so in nearly every birthweight stratum (the numbers are too small for statistical significance). The neonatal unit continued to receive sicker babies for at least 6 y. Then during 1992–95 [following the advent of surfactant and publication of the metaanalysis of randomized trials of antenatal corticosteroids (2)] the obstetricians increased their use of antenatal steroids and probably adopted more aggressive intrapartum care. Perinatal care is not simply the sum of its component technologies; practice style counts. It is no wonder that the clinicians felt a need to perform an audit. It is a brave act; we must all learn from it. The performance of NICUs cannot be evaluated in isolation. The antecedent obstetric care conveys to the NICU babies who are in better or worse condition. The most visible mechanism of ensuring optimal condition of the newborn is the aggressive use of antenatal corticosteroids in cases of threatened preterm delivery. There are certainly other less well-studied mechanisms involving; the timing of delivery to avoid infectious complications, intrapartum management, avoidance of acidosis, and route of delivery. All of these are predicated on attitudes towards intervention (3). Alternatively, the failure may be due to the structure of the healthcare system including geography and referral patterns as well as access to care and the biologic effects of social deprivation. A high newborn mortality rate may eflect poor performance in any of three consecutive epochs in the continuum of perinatal care: the antenatal period, during labour and shortly after birth, or in the neonatal unit after the peripartum period. This is well illustrated by experience in developing countries where both antenatal care and neonatal resuscitation are inadequate. As a result, NICUs in that setting admit more everely ill infants, so birthweight or gestation specific mortality is high. Despite this, the excellent postnatal care provided in some of these NICUs is demonstrated by rates of mortalityafter adjusting for CRIBthat are no different from those in more developed countries (4). This introduces a novel concept. By measuring severity of neonatal illness up to a baseline shortly after birth, we can begin to separate the effects of care before and after that baseline. By incorporating systems like CRIB and the Score for Neonatal Acute Physiology (SNAP) (5) into routine data collection, new insights may be gained into perinatal audit. This strategy was recently explored by Baumer et al. in a 10-y retrospective audit of a NICU in the UK (6). Beyond the policy issues, this article raises some important methodological issues. First, it is manifestly clear that interpretation of this study is affected by the meticulous reporting of a population-based cohort, especially the enumeration of delivery room deaths. Only by counting these cases could these authors rebut the argument that the obstetric population might have changed. If others wish to make a similar case, it will become unacceptable to publish reports of outcomes of only those infants surviving to NICU admission. Second, neonatal outcome, measured after months of the NICU care, may be a poor measure of the effectiveness of intrapartum high-risk care. Neonatal condition on admission (as reflected in the physiologic derangements of CRIB) may be a more proximate and sensitive indicator of the success obstetric interventions. A third methodological issue is whether and when to adjust for illness severity (such as CRIB or SNAP). For example, antenatal corticosteroids reduce the frequency and severity of neonatal respiratory distress syndrome, necrotizing enterocolitis and possibly intraventricular hemorrhage. Not surprisingly, antenatal corticosteroids therefore duce measured newborn illness severity (7, 8). Therefore, in comparing the performance of obstetric units, one should Acta Pædiatr 87: 134–5. 1998