Search PubMed⌕ Search

Biomedical subjects

T B Newman

Publications and source records attributed to T B Newman.

At least 19 recordsLinked to original sources
PubMed1992

Position statement: cholesterol screening in children is not indicated, even with positive family history.

The same reasons for the policy of rejecting universal blood cholesterol screening in all children also lead us to reject selective screening in those with a family history of premature CHD or high blood cholesterol. It is probably true that this large group--roughly 25% of all children, 12 million in the United States and many tens of millions worldwide--is at somewhat higher risk than the other 75% of children of eventually dying of CHD many decades later. But the small size and remoteness of any benefit achieved by cholesterol intervention is illustrated by the projection that we would need to treat 300 girls in the top cholesterol quintile, and treat them effectively for 50-60 years, in order to defer just one premature CHD death before age 65. The benefits of cholesterol screening and treatment in children are not only very small and remote, they are also uncertain; we have no firm evidence that they exist. The benefits are not needed, given the clinical trial evidence that most of the risk associated with high blood cholesterol among adults is reversible, even when intervention is not begun until middle age. The harmful effects of cholesterol screening and treatment are more firmly established than the benefits, and some are very serious. Such a program would be expensive orders of magnitude from conventional criteria for cost effectiveness. It would cause malnutrition in some children, and have the adverse consequences of labelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1992

Evaluation and treatment of jaundice in the term newborn: a kinder, gentler approach.

Standard recommendations for evaluating and treating jaundice in term babies include following all babies closely for jaundice, obtaining several laboratory tests in those with early jaundice or bilirubin levels more than 12 to 13 mg/dL (205 to 222 mumol/L), using phototherapy to try to keep bilirubin levels below 20 mg/dL (342 mumol/L), and doing exchange transfusions if phototherapy fails, regardless of the cause of the jaundice. These recommendations are likely to lead to unnecessary testing and treatment of many jaundiced term infants. Because most jaundiced infants have no underlying illness, and the generally recommended laboratory tests lack sensitivity and specificity, they are seldom useful. In most babies, the only blood tests needed to evaluate jaundice are the blood type and group (of baby and mother) and a direct Coombs' test. A determination of direct bilirubin level should be added if jaundice is prolonged (greater than 2 to 4 weeks) or the baby has other signs of illness. Bilirubin toxicity is rare in term babies without hemolysis. In this low-risk group, the risks and cost of identifying and treating high bilirubin levels may exceed the benefits. Such infants need not be closely followed for jaundice. If significant jaundice is nonetheless found, treatment should be deferred to relatively high levels of serum bilirubin, with a goal of keeping bilirubin levels below 400 to 500 mumol/L (23.4 to 29.2 mg/dL). Babies with hemolytic disease should be followed more closely, and their bilirubin levels kept below 300 to 400 mumol/L (17.5 to 23.4 mg/dL). These recommendations should be reevaluated as new data become available. In the meantime, currently available data justify an approach to the jaundiced term infant that is less aggressive than previously recommended.

Bilirubin↗
PubMed1991

The draft lottery and AIDS: evidence against increased intravenous drug use by Vietnam-era veterans.

To investigate whether intravenous drug use begun during military service might affect risk of acquired immunodeficiency syndrome (AIDS), the authors compared AIDS cases in men eligible to be drafted with those in men who were exempt in the Vietnam-era draft lottery of 1970-1972. Draft-eligible men were less likely to develop AIDS attributed to intravenous drug use than were draft-exempt men (relative risk = 0.87; 95% confidence interval 0.80-0.95; p = 0.001). Other human immunodeficiency virus exposure categories showed no difference between the two groups. These results argue against increased intravenous drug use by Vietnam-era veterans.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Direct bilirubin measurements in jaundiced term newborns. A reevaluation.

To investigate the usefulness of measuring direct bilirubin in jaundiced term newborns, we reviewed the outcome of 5255 such measurements on 2877 term (37 weeks' gestation) newborns in two hospitals. Direct bilirubin tests were ordered 15 times as often per infant at the University of California, San Francisco, as at Stanford (Calif) University, and the reported results were more than twice as high. In most of the 149 infants with high (greater than 95th percentile) direct bilirubin levels, the high levels remained unexplained (52% of cases) or were due to apparent laboratory errors (21% of cases). Forty infants (27%) had conditions sometimes associated with high direct bilirubin levels. Elevation of direct bilirubin levels contributed to the diagnosis in only four of these infants. All had minor laboratory abnormalities that resolved spontaneously. Because of their low yield and poor specificity, direct bilirubin tests are seldom helpful in evaluating jaundice in term newborns.

Bilirubin↗
PubMed1991

In defense of standardized regression coefficients.

The association between a risk factor and a disease can be expressed as a standardized regression coefficient derived from a logistic model. When exponentiated, this standardized coefficient equals the odds ratio associated with a one-standard-deviation change in the risk factor. Some epidemiologists have recently recommended that standardized regression coefficients not be used in epidemiologic research. We disagree and provide examples that demonstrate that, when a risk factor is continuous, standardized regression coefficients may be helpful for comparing variables measured in different units. Standardized regression coefficients may also be helpful for comparing the effect of the same risk factor in different populations. Misinterpretations can be avoided if the standard deviations of the variables of interest are also provided. There is no reason to abandon the use of standardized regression coefficients in epidemiologic analyses.

Epidemiologic Methods↗
PubMed1990

The case against childhood cholesterol screening.

Because some authorities have proposed blood cholesterol screening for children to prevent coronary heart disease, we reviewed published studies to estimate the potential risks and benefits of such screening. Childhood cholesterol levels are a poor predictor of high cholesterol levels in young adulthood and will be an even poorer predictor of coronary heart disease later in life. There is no evidence that blood cholesterol levels can be lowered more easily in children than in adults, and it seems unlikely that cholesterol reduction in childhood will be much more effective at preventing coronary heart disease than cholesterol reduction begun in middle age. Screening and interventions to lower blood cholesterol levels for millions of children would be expensive, could lead to labeling and family conflicts, and may cause malnutrition and increased noncardiovascular mortality. Because the benefits of cholesterol screening are unlikely to exceed these risks, we conclude that children should not be screened for high blood cholesterol levels.

Adult↗
PubMed1990

Laboratory evaluation of jaundice in newborns. Frequency, cost, and yield.

Neonates with hyperbilirubinemia commonly undergo a battery of laboratory tests. We used a computerized database and medical records to study the frequency, cost, and yield of these tests in 2443 infants born at the University of California, San Francisco, between 1980 and 1982. Four hundred forty-seven (18%) of the infants met standard criteria for "nonphysiologic" hyperbilirubinemia; the incidence varied from 9% in blacks to 31% in Asian infants. About 55% of these 447 infants received a $125 "hyperbilirubinemia workup." Hospital discharge diagnoses on all 447 hyperbilirubinemic infants were reviewed. In 214 (48%), no cause of the jaundice was identified. An additional 145 (32%) had a possible cause apparent from history, physical examination, or initial hematocrit determination. The only diagnosis made as a result of routine investigations of hyperbilirubinemia was possible ABO or Rh isoimmunization in 75 infants (17%). Nonphysiologic hyperbilirubinemia may be more common than previously reported. The recommended tests are expensive and rarely lead to diagnoses other than ABO or Rh isoimmunization. Their routine use should be reevaluated.

Cost-Benefit Analysis↗
PubMed1990

Does hyperbilirubinemia damage the brain of healthy full-term infants?

In the 1950s, exchange transfusion to keep the total serum bilirubin below 20 mg/dl was shown to be an effective way of preventing kernicterus in babies with erythroblastosis fetalis. For the last 15 to 20 years this level has also been used to determine the need for intervention in healthy full-term infants who do not have hemolytic disease. A critical review of all the available data including six studies from the collaborative perinatal project (more than 30,000 infants) and several smaller studies of term infants without hemolysis reveals essentially no evidence of adverse effects of bilirubin on IQ, neurologic examination, or hearing. The investigation and treatment of normal infants with jaundice is expensive and potentially harmful. We need to reassess our approach to hyperbilirubinemia in healthy full-term infants.

Bilirubin↗
PubMed1989

Sample size and power based on the population attributable fraction.

Most methods for calculating sample size use the relative risk (RR) to indicate the strength of the association between exposure and disease. For measuring the public health importance of a possible association, the population attributable fraction (PAF)--the proportion of disease incidence in a population that is attributable to an exposure--is more appropriate. We determined sample size and power for detecting a specified PAF in both cohort and case-control studies and compared the results with those obtained using conventional estimates based on the relative risk. When an exposure is rare, a study that has little power to detect a small RR often has adequate power to detect a small PAF. On the other hand, for common exposures, even a relatively large study may have inadequate power to detect a small PAF. These comparisons emphasize the importance of selecting the most pertinent measure of association, either relative risk or population attributable fraction, when calculating power and sample size.

Epidemiologic Methods↗