Michael H. Malloy

The changing concept of sudden infant death syndrome: Diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk

There has been a major decrease in the incidence of sudden infant death syndrome (SIDS) since the American Academy of Pediatrics (AAP) released its recommendation in 1992 that infants be placed down for sleep in a nonprone position. Although the SIDS rate continues to fall, some of the recent decrease of the last several years may be a result of coding shifts to other causes of unexpected infant deaths. Since the AAP published its last statement on SIDS in 2000, several issues have become relevant, including the significant risk of side sleeping position; the AAP no longer recognizes side sleeping as a reasonable alternative to fully supine sleeping. The AAP also stresses the need to avoid redundant soft bedding and soft objects in the infants sleeping environment, the hazards of adults sleeping with an infant in the same bed, the SIDS risk reduction associated with having infants sleep in the same room as adults and with using pacifiers at the time of sleep, the importance of educating secondary caregivers and neonatology practitioners on the importance of “back to sleep,” and strategies to reduce the incidence of positional plagiocephaly associated with supine positioning. This statement reviews the evidence associated with these and other SIDS-related issues and proposes new recommendations for further reducing SIDS risk.

Changes in the classification of sudden unexpected infant deaths: United States, 1992-2001

Background. Sudden infant death syndrome (SIDS) makes up the largest component of sudden unexpected infant death in the United States. Since the first recommendations for supine placement of infants to prevent SIDS in 1992, SIDS postneonatal mortality rates declined 55% between 1992 and 2001. Objective. The objective of this analysis was to examine changes in postneonatal mortality rates from 1992 to 2001 to determine if the decline in SIDS was due in part to a shift in certification of deaths from SIDS to other causes of sudden unexpected infant death. In addition, the analysis reviews the change in mortality rates attributed to the broad category of sudden unexpected infant death in the United States since 1950. Methods. US mortality data were used. The International Classification of Diseases (ICD) chapters “Symptoms, Signs, and Ill-Defined Conditions” and “External Causes of Injury” were considered to contain all causes of sudden unexpected infant death. The following specific ICD (ninth and tenth revisions) underlying-cause-of-death categories were examined: “SIDS,” “other unknown and unspecified causes,” “suffocation in bed,” “suffocation-other,” “aspiration,” “homicide,” and “injury by undetermined intent.” The average annual percentage change in rates was determined by Poisson regression. An analysis was performed that adjusted mortality rates for changes in classification between ICD revisions. Results. The all-cause postneonatal mortality rate declined 27% and the postneonatal SIDS rate declined 55% between 1992 and 2001. However, for the period from 1999 to 2001 there was no significant change in the overall postneonatal mortality rate, whereas the postneonatal SIDS rate declined by 17.4%. Concurrent increases in postneonatal mortality rates for unknown and unspecified causes and suffocation account for 90% of the decrease in the SIDS rate between 1999 and 2001. Conclusions. The failure of the overall postneonatal mortality rate to decline in the face of a declining SIDS rate in 1999–2001 raises the question of whether the falling SIDS rate is a result of changes in certifier practices such that deaths that in previous years might have been certified as SIDS are now certified to other non-SIDS causes. The observation that the increase in the rates of non-SIDS causes of sudden unexpected infant death could account for >90% of the drop in the SIDS rates suggests that a change in classification may be occurring.

Impact of Cesarean Section on Neonatal Mortality Rates Among Very Preterm Infants in the United States, 2000–2003

OBJECTIVE. The objective of this analysis was to compare the neonatal mortality rates for infants delivered through primary cesarean section versus vaginal delivery, taking into consideration a number of potentially risk-modifying conditions. METHODS. US linked birth and infant death certificate files for 2000–2003 were used. Demographic, medical, and labor and delivery complications were abstracted from the files with infant information. The primary outcome examined was neonatal death (death at 0–27 days of age). Because of concern regarding misclassification of gestational age, a procedure was used to trim away births for which the birth weight for a specific gestational age was incongruous. Adjusted odds ratios were calculated for the risk of neonatal death relative to the mode of delivery (primary cesarean section versus vaginal delivery), using logistic regression analysis. RESULTS. There were data for 13 733 neonatal deaths and 106 809 survivors available from the trimmed data set for analysis for the 4-year period. More than 80% of pregnancies with delivery between 22 and 31 weeks of gestation experienced ≥1 risk factor. Adjusted odds ratios demonstrated significantly reduced risk of neonatal death for infants delivered through cesarean section at 22 to 25 weeks of gestation (adjusted odds ratios of 0.58, 0.52, 0.72, and 0.81 for 22, 23, 24, and 25 weeks, respectively). CONCLUSION. Cesarean section does seem to provide survival advantages for the most immature infants delivered at 22 to 25 weeks of gestation, independent of maternal risk factors for cesarean section.

Dietary patterns of U.S. children: Implications for disease prevention☆

Nutritional data from the second National Health and Nutrition Examination Survey (NHANES II) were analyzed to assess dietary patterns of a representative sample of U.S. children and youth ages 1-17 years. The data show that the average U.S. childs diet is relatively high in total and saturated fat and low in the ratio of polyunsaturated to saturated fat. These dietary patterns deviate from current dietary recommendations for the prevention of cardiovascular diseases. The percentage contributions of specific macronutrients to total energy intake (in kilocalories) were total fat, 35-36%; total carbohydrates, 49-51%; and protein, 15-16%. This is in contrast to current expert recommendations for children of 30% of kilocalories as total fat, 55% as carbohydrates, and 15% as protein. The observed intake of saturated fat in U.S. children was 13% of kilocalories vs a recommended level of 10% of kilocalories. The observed ratio of polyunsaturated to saturated fat intake was 0.4 vs a recommended ratio of 1.0. There were important racial differences in fat intakes, with blacks generally having higher cholesterol and total fat intakes. White children generally consumed more of their calories as carbohydrates than did black children, but there were no differences in protein intakes between the two groups. In summary, these data suggest that the average U.S. childs diet deviates from recommended dietary guidelines for fat and cholesterol intakes. Black childrens dietary patterns appear less favorable for cardiovascular health than those of white children. However, the data also show that achieving recommended dietary intake patterns probably will not require drastic changes in the U.S. childs diet.

Decreased incidence of bronchopulmonary dysplasia after early management changes, including surfactant and nasal continuous positive airway pressure treatment at delivery, lowered oxygen saturation goals, and early amino acid administration: A historical cohort study

OBJECTIVE. The goal was to investigate the clinical impact of 3 early management practice changes for infants of ≤1000 g. METHODS. We performed an historical cohort study of appropriately sized, preterm infants without congenital anomalies who were born between January 2001 and June 2002 (pre–early management practice change group; n = 87) and between July 2004 and December 2005 (post–early management practice change group; n = 76). RESULTS. Only 1 (1%) of 87 infants in the pre–early management practice change group received continuous positive airway pressure treatment in the first 24 hours of life, compared with 61 (80%) of 76 infants in the post–early management practice change group. The proportions of infants who required any synchronized intermittent mandatory ventilation during their hospital stays were 98.8% and 59.5%, respectively. The mean durations of synchronized intermittent mandatory ventilation were 35 days and 15 days, respectively. The combined incidence rates of moderate and severe bronchopulmonary dysplasia at corrected gestational age of 36 weeks were 43% and 24%, respectively. The use of vasopressor support for hypotension in the first 24 hours of life decreased from 39.1% (before early management practice changes) to 19.7% (after practice changes), the cumulative days of oxygen therapy decreased from 77 ± 52 days to 56 ± 47 days, and the proportions of infants discharged with home oxygen therapy decreased from 25.7% to 10.1%; the incidence of patent ductus arteriosus requiring surgical ligation increased from 1% to 10%.There were no differences in rates of death, intraventricular hemorrhage, periventricular leukomalacia, pneumothorax, necrotizing enterocolitis, or retinopathy of prematurity. CONCLUSIONS. Successful early management of extremely preterm infants with surfactant treatment followed by continuous positive airway pressure treatment at delivery, lowered oxygen saturation goals, and early amino acid supplementation is possible and is associated with reductions in the incidence and severity of bronchopulmonary dysplasia.

Does breast-feeding influence intelligence quotients at 9 and 10 years of age?

The effect of breast-feeding on intellectual development remains controversial. We explored this relationship in a high socioeconomic population in which breast-feeding was supplemented with soy containing formulas at some time during the first year of life. As part of the 1988 National Institute of Child Health and Human Development school-based survey of two metropolitan Washington, D.C. counties to identify children in the 1978 to 1979 birth cohort who had been exposed to the chloride deficient formulas Neo-Mull-Soy and Cho-Free during infancy, information on breast-feeding was also obtained on children exposed to the chloride-deficient formulas and a group of control children exposed to other soy formulas. Because no differences in intellectual development were observed between the two groups, they were combined and the effect of breast-feeding on intellectual development at 9 and 10 years was assessed. There were 176 infants that received no breast-feeding and 342 who were breast-fed. The median duration of breast-feeding was 124 days (interquartile range, 42-248 days). There were no differences in birth weight, gender or race between the infants who were breast-fed and those who were not. The mean Weschler Intelligence Scale-Revised Full Scale IQ was 122 among those breast-fed compared to 118 among those that were not (P = 0.0008). However, following adjustment by linear regression for maternal education, paternal education and annual income the adjusted mean full scale IQ was 111 among the breast-fed and 110 among the non-breast-fed (P = 0.23). Further analyses limited to those exclusively breast-fed for the first 60 days failed to demonstrate any significant relationship between breast-feeding and IQ.

Sudden infant death syndrome and maternal smoking.

Data from Missouri for the period 1980 to 1985 suggest a dose-response relationship between smoking during pregnancy and the incidence of sudden infant death syndrome (SIDS). However, data from the National Institute of Child Health and Human Development SIDS Cooperative Epidemiological Study did not support a dose-response relationship. Neither the Missouri data nor the Cooperative Study data support a relationship between the age of occurrence of SIDS and smoking during pregnancy.

Colonization and infection associated with Malassezia and Candida species in a neonatal unit

The objectives of this study were to determine, in neonates of < 1250 g birthweight (N = 57), the initial time of skin colonization by Malassezia furfur, rate of colonization by Candida spp., and whether skin colonization by these yeasts was predictive of central line colonization or fungaemia. By age two weeks, 51% of neonates were culture-positive for M. furfur on umbilical or groin skin. During hospitalization, positive skin cultures for M. furfur or Candida spp. were obtained in 70% and 37% of neonates, respectively. Risk factors associated with positive skin cultures were mechanical ventilation and three or more episodes of suspected sepsis. Eight of the 52 infants with central venous catheters, had positive blood cultures withdrawn from the lines; five (62%) of these had positive skin surveillance cultures. Although positive skin cultures for M. furfur, Candida spp., or both were commonly observed in this population, they were not predictive of positive central line cultures or systemic illness.

Prematurity and sudden infant death syndrome: United States 2005-2007

Objective:In 1987, the sudden infant death syndrome (SIDS) rate in the United States was 1.2 per 1000 live births. By the year 2005, the SIDS rate had dropped more than half to approximately 0.5 per 1000 live births. In 1987, the risk of SIDS was 2.32 times greater for extremely premature infants compared with term infants. The objective of this analysis was to determine if with the falling SIDS rate there has been a change in the risk for SIDS among preterm infants.Study Design:Data were obtained from the United States Linked Infant Birth and Death Certificate Public User Period files for the years 2005 to 2007. The adjusted odds ratios (ORs) for postneonatal out-of-hospital death by gestational age were determined by logistic regression modeling.Result:Over the 3-year period, there were 5203 postneonatal out-of-hospital deaths attributable to SIDS; 2010 attributable to other sudden deaths; 1270 attributable to suffocation in bed; and 3681 attributable to other causes. The adjusted OR for SIDS among the most preterm infants (24 to 28 weeks gestation) was significantly increased compared with term infants, ORadj=2.57 (95% confidence interval=2.08, 3.17), as were the adjusted ORs for the other causes of sudden infant death.Conclusion:Despite the marked drop in the incidence of SIDS since 1987, the risk for SIDS among preterm infants remains elevated. Other causes of sudden infant death for which SIDS is often mistaken reflect similar levels of increased risk among preterm infants.

Respiratory distress syndrome mortality in the United States, 1987 to 1995.

OBJECTIVE: To review respiratory distress syndrome (RDS) mortality since the introduction of surfactant.DESIGN: Population-based historical cohort study.METHODS: United States vital statistic data were used for the years 1987 to 1995. Linked birth and infant death file data were available for the years 1987 to 1991 and for 1995. US natality and mortality files were used for the years 1992 to 1994.RESULTS: Whereas overall infant mortality decreased 25% over the-9 year period from a rate of 979 deaths/100,000 live births (LB) to a rate of 736, mortality attributed to RDS decreased 56% from a rate of 84 to 37. The crude black:white relative risk for RDS-related mortality increased from 2.02 in 1987 to 2.76 in 1995. The largest and most consistent drop in RDS-related mortality occurred in the 2000 to 2499 gm birth weight and 33- to 36-week gestation groups; average annual decline=20%. There was a change in the distribution of the underlying causes of death over the 9-year period with an increase in the proportion of mortality attributed to prematurity.CONCLUSION: Since the advent of surfactant there has been a marked reduction in mortality attributed to RDS. Of concern is the increasing disparity between black and white RDS-related mortality.