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.

Low-level lead exposure, social class, and infant development.

A prospective cohort study was conducted to assess the association between early development and low-level prenatal and postnatal lead exposure. Infants' performance between 6 and 24 months on the Mental Development Index of the Bayley Scales of Infant Development declined with increasing concentration of lead in blood, but the decline varied with children's age at exposure, level of exposure, and socioeconomic status. Within the second year of life, the performance of children in lower socioeconomic strata was adversely affected at lower levels of prenatal exposure (blood lead levels of 6 to 7 micrograms/dl) than was the performance of children in higher socioeconomic strata. However, even the performance of these advantaged infants was lower when cord blood lead level exceeded 10 micrograms/dl, well below the figure currently regarded as the maximum permissable level for young children. Exploratory analyses suggested that early postnatal blood lead levels between 10 and 25 micrograms/dl were also associated with lower Mental Development Index scores, but only among children in lower socioeconomic strata.

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.

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.

PIP: Because a large proportion of preschool children failed to present for free diphteria-pertussis-tetanus (DPT) immunization in a poor, rural area of the Philippines, the authors 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 behavior were not useful discriminators. Recommendations are made for immunization program management. The general use of this method for program planning is elaborated.

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.

Impact of a cardiology data bank on physicians' prognostic estimates. Evidence that cardiology fellows change their estimates to become as accurate as the faculty.

To determine whether physicians would be influenced by the prognostic information in a large coronary artery disease data bank, cardiology faculty and fellows made initial estimates of the prognoses of their patients and then made revised final estimates after seeing the outcome of matched patients (OMP) from the data bank. The faculty cardiologists' original estimates proved to be as accurate as those of the data bank's OMP, and the faculty revised their estimates minimally in response to the data bank's OMP. Conversely, the cardiology fellows' original estimates were less accurate than the data bank's OMP, and under all observed circumstances the fellows responded more to the data bank's OMP than did the faculty. As a result, the accuracy of the fellows' final estimates was similar to the accuracies of both the faculty cardiologists and the data bank's OMP. Computerized data banks seem more likely to have impact when their information is provided to physicians who are relatively inexperienced with the disease in question.