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C Waternaux

Publications and source records attributed to C Waternaux.

At least 37 records · Page 2Linked to original sources
PubMed1991

Urinary 3-methoxy-4-hydroxyphenylglycol and the depression-type score as predictors of differential responses to antidepressants.

Pretreatment 24 hr urinary 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and the Depression-type (D-type) scores (derived from a multivariate discriminant function equation based on levels of urinary catecholamines and metabolites) were examined as possible predictors of antidepressant responses to either imipramine or alprazolam. In the case of imipramine, the responders had significantly lower pretreatment urinary MHPG levels (p = 0.002) and D-type scores (p less than 0.001) than did nonresponders. In contrast, responders to the antidepressant effects of alprazolam had significantly higher pretreatment urinary MHPG levels (p less than 0.05) and D-type scores (p = 0.02) than did nonresponders. For each antidepressant treatment, D-type scores appeared to provide a better separation of responders from nonresponders than did urinary MHPG levels. For each drug, the effect size for the difference in mean log-transformed D-type scores between responders and nonresponders was greater than the effect size for the difference in mean log-transformed MHPG levels. The difference between the effect sizes was statistically significant for imipramine (p = 0.02) and tended toward significance for alprazolam using two-tailed tests. These results suggest that the D-type equation, which was initially derived to separate bipolar manic-depressive depressions from other subgroups of depressive disorders, can also be used to predict differential responses to certain antidepressant drugs in patients with unipolar depressions.

Adult↗
PubMed1991

Low-level lead exposure and children's cognitive function in the preschool years.

In a cohort of 170 middle and upper-middle class children participating in a prospective study of child development and low-level lead exposure, higher blood lead levels at age 24 months were associated with lower scores at age 57 months on the McCarthy Scales of Children's Abilities. The mean blood lead level at age 24 months was 6.8 micrograms/dL (SD = 6.3; 75th, 90th, and 99th percentiles: 8.8, 13.7, 23.6, respectively) and for all but 1 child was less than 25 micrograms/dL, the current definition of an "elevated" level. After adjustment for confounding, scores on the General Cognitive Index decreased approximately 3 points (SE = 1.4) for each natural log unit increase in 24-month blood lead level. The inverse association between lead level and performance was especially prominent for visual-spatial and visual-motor integration skills. Higher prenatal exposures were not associated with lower scores at 57 months except in the subgroup of children with "high" concurrent blood lead levels (ie, greater than or equal to 10 micrograms/dL). The concentration of lead in the dentine of shed deciduous teeth was not significantly associated with children's performance after adjustment for confounding.

Age Factors↗
PubMed1989

A fixed dose study of the plasma concentration and clinical effects of thioridazine and its major metabolites.

Fifty-three patients in an acute episode or exacerbation of psychosis were given thioridazine 200 or 400 mg daily for 2 weeks. Thioridazine and its active metabolites, mesoridazine and sulforidazine, were estimated in plasma by high performance liquid chromatography (HPLC) and radioreceptor assay (RRA). One week after institution of treatment, plasma concentrations of drug were stable in the morning 12h after dosing. Drug levels varied widely between patients, but in all patients the relative level of thioridazine to mesoridazine was about one half and thioridazine to sulforidazine was about two fold. Estimates of neuroleptic activity by RRA and the weighted sum of thioridazine, mesoridazine and sulforidazine by HPLC were very similar. Plasma concentration of parent compound, metabolites, or the sum of active substances as estimated by HPLC or RRA, showed only modest correlations (rs = 0.10-0.22, all NS) to the degree of improvement as measured by change on the Brief Psychiatric Rating Scale. Significant correlations were observed between plasma concentrations of drug and side effects, including dry mouth, blurred vision, or total rating on the Somatic Symptoms Scale. Even patients receiving the lowest dose and achieving the lowest plasma concentrations of drug showed considerable improvement. There was suggestive evidence that the patients achieving the highest plasma levels of drug did not have the best clinical outcome. These and similar observations from other studies suggest that currently used doses of neuroleptics may be excessive. Optimal drug effects as well as stronger relationships between dose, drug concentration, and clinical therapeutic effects might best be sought at doses below those in common use.

Adolescent↗
PubMed1989

Lead, IQ and social class.

Social class (SC) conveys information about a child's potential lead exposure (PB) as well as other, independent determinants of cognition (IQ). Thus, depending on the way in which SC is handled in statistical analyses, the PB-IQ association may be either 'overadjusted' or 'underadjusted' for SC. Two assumptions that underlie the inclusion of SC in correlation/regression analyses of the PB-IQ relationship are: 1) SC is an interval scale and 2) the PB-IQ relationship is homogeneous in all social strata. Simulation analyses are presented to illustrate the impact that different values of the bivariate correlations PB-SC, IQ-SC, and PB-IQ have on the estimate of the PB-IQ adjusted for SC. Alternative approaches to addressing these issues are discussed.

Child↗
PubMed1989

Investigating drug plasma levels and clinical response using random regression models.

The reanalysis of the Riesby dataset using a random regression model indicates a significant effect of DMI plasma measurements on HAM-D scores across the four timepoints of the study. This effect is especially strong when the HAM-D change from baseline score is used in place of the actual HAM-D score at the four timepoints. A significant effect of IMI was not found for either the actual HAM-D score or the HAM-D change from baseline score. An endogenous effect was marginally significant when the actual HAM-D score was used; however, this effect was not observed when the HAM-D change score was used as the dependent measure. There also was evidence of a marginally significant effect due to autocorrelation of the residuals, indicating that the residuals at a given timepoint were related to the residuals from previous timepoints according to a first-order autoregressive process. In contrast, when the repeated measures MANOVA was used to analyze these data, a significant effect of DMI was not observed, since subjects without complete data at all timepoints had to be dropped from the analysis. In longitudinal psychiatric studies where missing data are the rule (rather than the exception), the random regression approach provides an attractive alternative to the traditional methods of analyzing longitudinal data.

Humans↗
PubMed1987

Longitudinal analyses of prenatal and postnatal lead exposure and early cognitive development.

In a prospective cohort study of 249 children from birth to two years of age, we assessed the relation between prenatal and postnatal lead exposure and early cognitive development. On the basis of lead levels in umbilical-cord blood, children were assigned to one of three prenatal-exposure groups: low (less than 3 micrograms per deciliter), medium (6 to 7 micrograms per deciliter), or high (greater than or equal to 10 micrograms per deciliter). Development was assessed semiannually, beginning at the age of six months, with use of the Mental Development Index of the Bayley Scales of Infant Development (mean +/- SD, 100 +/- 16). Capillary-blood samples obtained at the same times provided measures of postnatal lead exposure. Regression methods for longitudinal data were used to evaluate the association between infants' lead levels and their development scores after adjustment for potential confounders. At all ages, infants in the high-prenatal-exposure group scored lower than infants in the other two groups. The estimated difference between the overall performance of the low-exposure and high-exposure groups was 4.8 points (95 percent confidence interval, 2.3 to 7.3). Between the medium- and high-exposure groups, the estimated difference was 3.8 points (95 percent confidence interval, 1.3 to 6.3). Scores were not related to infants' postnatal blood lead levels. It appears that the fetus may be adversely affected at blood lead concentrations well below 25 micrograms per deciliter, the level currently defined by the Centers for Disease Control as the highest acceptable level for young children.

Child Development↗
PubMed1987

Methodology in psychiatric research. Report on the 1986 MacArthur Foundation Network I Methodology Institute.

This report discusses many of the issues raised during a two-day institute that focused on methodological problems encountered in psychiatric research. The topics range from the problems with psychiatric diagnosis and measurement to sampling issues and biases to specific statistical concerns. Attention is given to the need for improved communication and collaboration between psychiatric researchers and biostatisticians.

Biometry↗
PubMed1987

High rate of affective disorders in probands with attention deficit disorder and in their relatives: a controlled family study.

In a controlled family study of attention deficit disorder, data were collected on first-degree relatives of 22 children with attention deficit disorder and 20 normal children. The rate of major affective disorder was significantly higher in the attention deficit disorder probands (32%) and their relatives (27%) than in the normal control subjects (0%) and their relatives (6%). The findings indicate that attention deficit disorder is associated with higher risk for affective disorder and suggest that probands who have both disorders may represent a distinct subgroup.

Adolescent↗
PubMed1987

Presentation of growth velocities of rural Haitian children using smoothing spline techniques.

The examination of monthly (or quarterly) increments in weight or length is important for assessing the nutritional and health status of children. Growth velocities are widely thought to be more important than actual weight or length measurements per se. However, there are no standards by which clinicians, researchers, or parents can gauge a child's growth. This paper describes a method for computing growth velocities (monthly increments) for physical growth measurements with substantial measurement error and irregular spacing over time. These features are characteristic of data collected in the field where conditions are less than ideal. The technique of smoothing by splines provides a powerful tool to deal with the variability and irregularity of the measurements. The technique consists of approximating the observed data by a smooth curve as a clinician might have drawn on the child's growth chart. Spline functions are particularly appropriate to describe bio-physical processes such as growth, for which no model can be postulated a priori. This paper describes how the technique was used for the analysis of a large data base collected on pre-school aged children in rural Haiti. The sex-specific length and weight velocities derived from the spline-smoothed data are presented as reference data for researchers and others interested in longitudinal growth of children in the Third World.

Body Height↗
PubMed1986

A family study of patients with attention deficit disorder and normal controls.

In a family study of Attention Deficit Disorder (ADD), we collected data on first-degree relatives of 22 children with ADD and 20 normal children. The morbidity risk for ADD was 31.5% in the first group. This was significantly higher than the rate of 5.7% in the control group. Relatives of ADD probands were also shown to be at higher risk for Oppositional Disorders and Major Depressive Disorder (MDD). The findings indicate that ADD is a familial disorder associated with increased familial risk of other psychiatric disorders.

Adolescent↗
PubMed1986

Correlates of low-level lead exposure in urban children at 2 years of age.

The blood lead levels of a large number of US preschool children approach the value regarded as the upper limit of normal. To reduce the number of children whose levels increase into the range thought to be toxic, the antecedents and correlates of levels in the 0- to 25-micrograms/dL range must be identified. In a large longitudinal study of middle and upper-middle class children living in metropolitan Boston, we evaluated how well five sets of variables predicted children's blood lead levels at 2 years of age: environmental lead sources, mouthing activity, home environment/care giving, prior developmental status, and sociodemographic characteristics. A series of bivariate and multivariate analyses indicated that only environmental lead sources and, to a lesser extent, mouthing activity accounted for significant portions of the variance in blood lead levels. Environmental lead sources were not significantly related to the home environment/care-giving variables or to sociodemographic characteristics. The most promising approach for achieving community-wide reductions in children's blood lead levels is reduction in the amount of lead in the proximate environment.

Analysis of Variance↗
PubMed1985

Environmental correlates of infant blood lead levels in Boston.

From a blood lead survey of 11,837 births, 249 newborns were enrolled in a 2-year, longitudinal study. Their blood leads (PbB) were measured semiannually, and their homes were visited for repeated collections of dust, soil, indoor air, tap water, and paint. Recent refinishing activity and the sizes of nearby streets were recorded. Overall mean PbB was 7.2 micrograms/dl (SD = 5.3) at birth. PbB did not vary systematically with age. Each subject's average postnatal PbB correlated highly with the amount of lead in dust (r = 0.4, P less than 0.0001) and soil (r = 0.3, P less than 0.001), and with the lead in paint (r = 0.2, P less than 0.01). Dust, soil and air lead levels correlated with one another. Refinishing activity in the presence of lead paint was associated with elevations of PbB. Water lead, proximate traffic, weight of recovered dust, race, maternal age and education, and sex were not predictive of PbB. Multivariate models of PbB were constructed that become increasingly predictive with age (r2 = 20 to 37%). Indoor dust lead, lead in soil, refinishing activity, and season were the independent variables.

Air Pollutants↗
PubMed1985

Methodological issues in modeling the relationship between low-level lead exposure and infant development: examples from the Boston Lead Study.

This paper addresses several methodological issues relevant to an assessment of the association between low-level lead exposure and early development. In particular, we discuss methods for choosing, from a large pool of candidates, the covariates to control when estimating this association. We examine the issue of confounding and explain why adjusting increased, rather than decreased, the estimate of the association between blood lead level and development at 6 months of age in our sample. A step-by-step description of our strategy for model building is presented. Finally, we demonstrate the robustness of the findings by showing that the magnitude and standard error of the estimated lead effect is not affected appreciably by the method of selecting covariates to be controlled for or by the characterization of lead as a continuous, ordinal, or dichotomous variable. Although these issues arose in the course of analyses of data collected by the Boston lead study (D. Bellinger, H. Needleman, A. Leviton, C. Waternaux, M. Rabinowitz, and M. Nichols (1984), Neurobehav. Tox. Teratol., 6, 387-402), they apply to other current prospective lead studies as well.

Analysis of Variance↗
PubMed1985

An epidemiological assessment of immunization programme participation in the Philippines.

Because a large proportion of preschool children failed to present for free diphtheria-pertussis-tetanus (DPT) immunizations in a poor, rural area of the Philippines, we undertook an epidemiological analysis of their characteristics. The parents of 159 children were interviewed to determine the demographic, attitudinal, knowledge, and administrative correlates of immunization status. Logistic regression was used to model immunization status. Children were less likely to be immunized if they had a high score on an Adversity Index (composed of measures of the weather, the number of visits the team made, the distance, the appropriateness of the time of day, and miscellaneous problems), if they received health care from a native mother and child health specialist, if a parent was not on the town council, and if pain was an important deterrent. By contrast, many demographic and attitudinal measures that have traditionally been thought to predict health behaviour were not useful discriminators. Recommendations are made for immunization programme management. The general use of this method for programme planning is elaborated.

Adult↗
PubMed1985

Plasma levels of neuroleptic in patients receiving depot fluphenazine.

Depot forms of fluphenazine are frequently used in the outpatient treatment of psychiatric patients. To gather relevant data on pharmacokinetic characteristics of depot fluphenazines, the authors measured plasma levels of neuroleptic activity in 76 clinic patients on stable dosage regimens of fluphenazine decanoate or fluphenazine enanthate. Dose and plasma neuroleptic activity level were highly correlated for both forms of depot fluphenazine. Furthermore, the slope of the regression of log dose to the log plasma neuroleptic activity was the same for both drug forms. However, doses of enanthate twice those of decanoate were associated with the same mean plasma level of neuroleptic activity. Finally, while blood levels of drug overlapped markedly in cohorts of patients receiving different doses of depot medication, the assumption of recent studies that, on the average, patients in such cohorts have different blood and tissue levels of drug was confirmed.

Delayed-Action Preparations↗
PubMed1984

Results, charges, and benefits of intensive care for critically ill patients: update 1983.

Objective and quantitative methods were used to measure severity of illness and outcome of intensive care in critically ill patients, in terms of success or failure of therapy within the ICU, survival or death at 1 yr, quality of life in survivors, and utilization of resources. One hundred ninety-nine consecutive Class IV critically ill surgical patients hospitalized between 1977 and 1978 at the Massachusetts General Hospital comprised the study population. Although the mortality rate of 69% was close to the 73% rate we recorded for 1972-1973, the survivors' quality of life was significantly better. Hospitalization costs increased from $15,000 to $22,000 per patient, almost consistent with the inflation rate between 1973 and 1978. Survival rates and quality of life in survivors did not vary with age. The disease process for which the patient was hospitalized was an important determinant of outcome. Intensive care medicine for critically ill surgical patients does prolong life and enable some patients to return to a productive lifestyle; however, the costs of these benefits are extremely high.

Adult↗