S. P. Wong

Forming inferences about some intraclass correlation coefficients

Although intraclass correlation coefficients (ICCs) are commonly used in behavioral measurement, psychometrics, and behavioral genetics, procedures available for forming inferences about ICCs are not widely known. Following a review of the distinction between various forms of the ICC, this article p

The relationship between labor and route of delivery in the preterm infant

The purpose of this prospective study was to evaluate the effects of the active phase of labor and route of delivery on the frequency of germinal layer/intraventricular hemorrhage in 89 infants with ultrasound-estimated fetal weights less than or equal to 1750 gm. Twenty-eight infants (31.5%) had germinal layer/intraventricular hemorrhage within 1 hour after birth and an additional 15 infants (17%) had germinal layer/intraventricular hemorrhage beyond 1 hour after birth. Infants with germinal layer/intraventricular hemorrhage had a significantly lower gestational age (p less than 0.003) and birth weight (p less than 0.007). Germinal layer/intraventricular hemorrhage within 1 hour after delivery was increased in the infants of women who experienced the active phase of labor regardless of the route of delivery. However, the incidence of germinal layer/intraventricular hemorrhage beyond 1 hour after delivery and the overall incidence were similar in the vaginal delivery and cesarean delivery groups. In addition, there was an increased incidence of progression to grades III and IV hemorrhage regardless of route of delivery in the infants whose mothers experienced the active phase of labor.

Asymptomatic syndrome of polycythemic hyperviscosity: effect of partial plasma exchange transfusion

We determined the cerebral hemodynamic changes in infants with asymptomatic polycythemic hyperviscosity syndrome and whether treatment with partial plasma exchange transfusion (PPET) would affect hemodynamics as well as outcome. From a routine cord blood hematocrit screening, 71 babies were identified as needing to be tested for polycythemic hyperviscosity. In addition to clinical evaluation, each infant had radial artery hematocrit and viscosity determinations, blood gas determinations, cerebral blood flow velocity studies, cranial ultrasonography, and noninvasive intracranial pressure determination. Babies with symptomatic hyperviscosity (n = 17) were treated by PPET, whereas those with asymptomatic hyperviscosity (n = 28) were randomly selected to have PPET (n = 14) or to be observed (n = 14). The remaining babies (n = 26) with normal viscosity served as control subjects. Both hematocrit and viscosity decreased after PPET but remained unchanged in babies with hyperviscosity who were merely observed. Reversal of cerebral blood flow velocity abnormalities was observed after PPET in the infants with symptomatic hyperviscosity, whereas those who had no symptoms had normal results on Doppler studies at the outset, and no significant changes occurred with either PPET or observation. There were two deaths in the group with symptoms. A total of 46 babies returned for follow-up evaluation at a mean age of 30 +/- 7.7 months. Outcome of the control group was no better than that of those who had hyperviscosity, and outcomes did not differ between the babies with symptomatic and those with asymptomatic hyperviscosity, nor between those treated with PPET and those who were only observed. Multivariate analysis revealed that other perinatal risk factors and race rather than polycythemia or PPET, significantly influenced long-term outcome.

Obstetric factors and relative risk of neonatal germinal layer/intraventricular hemorrhage.

One hundred fifty-five inborn infants with a birth weight less than or equal to 1,500 gm were prospectively evaluated for germinal layer/intraventricular hemorrhage. Maternal characteristics, obstetric factors, and neonatal condition in the immediate newborn period were analyzed as possible risk factors for germinal layer/intraventricular hemorrhage. Early germinal layer/intraventricular hemorrhage or hemorrhages identified during the first 24 hours of life were observed in 85 (55%) of these infants. Another 37 (24%) had germinal layer/intraventricular hemorrhage after 24 hours of age (late germinal layer/intraventricular hemorrhage). None of the maternal and obstetric variables, including labor, mode of delivery, and presentation, appeared to increase the risk of germinal layer/intraventricular hemorrhage. The immediate neonatal condition, birth weight, gestational age, and intrauterine growth, all influenced the occurrence of germinal layer/intraventricular hemorrhage, especially early germinal layer/intraventricular hemorrhage. We suggest that future studies to investigate the role of maternal or obstetric factors in the pathogenesis of germinal layer/intraventricular hemorrhage should discriminate early from late germinal layer/intraventricular hemorrhage. Obstetric factors are more likely to influence the early onset of germinal layer/intraventricular hemorrhage; their effect, if any, becomes less discernible later.

Controlled supplemental oxygenation during tracheobronchial hygiene

The effect of controlled supplemental oxygenation without bag ventilation on transcutaneous partial pressure of oxygen (TcPO2) measurements during tracheobronchial hygiene was evaluated. Procedure A, no supplemental oxygenation, was compared to Procedure B, in which controlled supplemental oxygenation was used. For controlled supplemental oxygenation, the FiO2 was increased until TcPO2 measurements rose to levels between 90 and 100 torr. Sixteen premature infants who required mechanical ventilation were studied in the neonatal center. Both procedures were performed on each patient in random order. In both procedures, a precipitous decrease in TcPO2 was observed during chest vibration, and further decrease in TcPO2 was noted with endotracheal suctioning. Except for baseline readings, throughout the tracheobronchial hygiene TcPO2 measurements were significantly higher and more subjects maintained TcPO2 values greater than 40 torr in Procedure B. In Procedure A corresponding TcPO2 measurements were 40 torr or less. Mean recovery time was shorter in Procedure B, 2.1 ± 2.3 minutes, than in Procedure A, 4.9 ± 2.8 minutes, p < .003. Thus, in most patients, controlled supplemental oxygenation without manual bag ventilation seems sufficient to prevent hypoxia during tracheobronchial hygiene; it also shortens recovery time from hypoxemia as a result of the bronchopulmonary hygiene procedure.

Confidence Intervals and F Tests for Intraclass Correlations Based on Three-Way Random Effects Models

This article gives equations for computing confidence interval estimates and conducting F tests for intraclass correlation coefficients (ICCs) defined using three-way random effects models for crossed and nested designs. The estimates and tests employ mean squares from analyses of variance. The equations are generalized so that data from an initial pilot study (G study) can be used to prophesy the confidence limits for ICCs in data with more or fewer factor levels. Equations also are included for determining the optimal number of factor levels to use in a design that will offer confidence of 1-[.alpha] that the population ICC is equal to or exceeds a fixed lower limit.

Confidence Intervals and F Tests for Intraclass Correlation Coefficients Based on Three-Way Mixed Effects Models

Intraclass correlation coefficients (ICCs) are commonly used in behavioral measurement and psychometrics when a researcher is interested in the relationship among variables of a common class. The formulas for deriving ICCs, or generalizability coefficients, vary depending on which models are specified. This article gives the equations for computing confidence intervals and conducting F tests for three-way mixed models with one fixed facet, extending the work on random effects models produced by Wong and McGraw. It provides the formula for finding the confidence interval for generalizability coefficients in the situations in which n i ′ is not necessarily equal to ni, where ni and n i ′ are the number of levels of facet i in generalizability and decision studies, respectively. The authors provide the formulas for finding n i ′ when the researcher wishes to maintain a minimum desired generalizability coefficient. Finally, the authors illustrate the analytic differences among four models using one hypothetical data set and then use real data from student course evaluations to further illustrate one of the four models.

Prognostic significance of cerebrospinal fluid cyclic adenosine monophosphate in neonatal asphyxia

OBJECTIVE In piglets prolonged asphyxia resulted in decreased cerebrospinal fluid (CSF) 3;,5;-cyclic adenosine monophosphate (cAMP) during recovery; this was associated with reduced pial arteriolar responses to stimuli that use cAMP as a second messenger. We hypothesized that asphyxia in human neonates results in decreased CSF cAMP and that low CSF cAMP is associated with abnormal outcome. DESIGN We studied 27 infants with evidence of hypoxic-ischemic insult; 19 were term (group 1) and 8 were preterm (group 2). The normal values of CSF cAMP were determined from 75 infants with no asphyxia; 44 were term (group 3) and 31 were preterm (group 4). CSF cAMP was measured by using radioimmunoassay procedures. RESULTS CSF cAMP levels in infants with asphyxia (groups 1 and 2) were 12 +/- 9. 5 and 7.9 +/- 7.1 pmol/mL, respectively, significantly lower than those of groups 3 and 4 (control infants), that is, 21.1 +/- 8.7 and 27.1 +/- 9.2 pmol/mL, respectively (P <.0001). Among infants with asphyxia, 3 died and 10 had abnormal neurologic outcome. Univariate analysis showed that abnormal outcomes were significantly related to CSF cAMP levels, phenobarbital use, and multi-organ failure. However, only CSF cAMP was retained in the model by stepwise logistic regression. CSF cAMP of 10.0 pmol/mL discriminated between those with normal and those with abnormal neurologic outcome. Low CSF cAMP concentration was associated with abnormal long-term outcome, estimated odds ratio of 12.4 (95% CI, 2.1-109.3; P <.006), and sensitivity, specificity, and positive and negative predictive values of 85%, 69%, 73%, and 80%, respectively. CONCLUSION CSF cAMP concentrations were decreased in infants with asphyxia. Low CSF cAMP levels were associated with poor neurologic outcome.

How Many Subjects to Screen? A Practical Procedure for Estimating Multivariate Normal Probabilities for Correlated Variables.

This article suggests a practical procedure for estimating the number of Ss that need to be screened to obtain a sample of fixed size that meets multiple correlated criteria. The procedure is based on the fact that least squares regression provides a good quadratic fit for Monte Carlo estimates of multivariate probabilities when they are plotted as a function of mean pairwise correlations (r) for the criterion variables. The equations given here can be used to predict selected 3- to 5-variable joint probabilities with reasonable accuracy as long as pairwise correlations for the selection criteria range from .10 to .90.

Anger Expression Mode, Depressive Symptoms, Hopelessness, and Decision Coping among African American Adolescents

This study examined the relationship between anger expression mode, depressive symptoms, hopelessness, and decision coping patterns among a non-clinical community sample of 276 low-income African American adolescents (mean age = 14.47). Participants were students in sixth through tenth grades enrolled in health and wellness classes in two public schools in West Tennessee. They were asked to complete a battery of instruments including the Anger Style Inventory, Childrens Depression Inventory, Hopelessness Scale for Children, and Flinders Adolescent Decision Making Questionnaire. Findings indicate a significant association between anger expression mode, depressive symptomatology, hopelessness, and decision coping pattern among study participants. Gender and screening positive for depressive symptoms predicted participants anger response mode. Using multiple assessment scales may provide useful information toward preventing the onset of clinically significant emotional disorders among adolescents.