Biomedical subjects
T B Newman
Publications and source records attributed to T B Newman.
Bilirubin and neurological dysfunction--do we need to change what we are doing?
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Indications for computed tomography after minor head injury.
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Prediction and prevention of extreme neonatal hyperbilirubinemia in a mature health maintenance organization.
OBJECTIVE: To investigate biological and health services predictors of extreme neonatal hyperbilirubinemia in a health maintenance organization. DESIGN: Nested case-control study. SETTING: Eleven Northern California Kaiser Permanente hospitals. SUBJECTS: The cohort consisted of 51,387 newborns born at 36 weeks or later weighing 2000 g or more. Cases were newborns with peak total serum bilirubin levels greater than or equal to 428 micromol/L (> or =25 mg/dL) (n = 73). Controls were a random sample of newborns from the cohort with peak bilirubin levels less than 428 micromol/L (<25 mg/dL) (n = 423). MEASUREMENTS: Review of medical records and telephone interviews. RESULTS: Early jaundice was most strongly associated with case status (odds ratio [OR] = 7.3). After excluding subjects with early jaundice, the strongest predictors of hyperbilirubinemia were family history of jaundice in a newborn (OR = 6.0), exclusive breastfeeding (OR = 5.7), bruising (OR = 4.0), Asian race (OR = 3.5), cephalhematoma (OR = 3.3), maternal age of 25 years or older (OR = 3.1), and lower gestational age (OR = 0.6/week). These variables identified 61% of newborns as very low risk (about 1/4200). However, the risk in the remaining 39% was still low (1/370). More cases (79%) than controls (59%) had newborn length-of-stay and follow-up consistent with the American Academy of Pediatrics guidelines, but phototherapy use within 8 hours of the time that the guidelines recommend was uncommon in both cases (26%) and controls (33%). There were no apparent cases of kernicterus. CONCLUSIONS: Prevention of extreme hyperbilirubinemia may require closer follow-up than is currently recommended by the American Academy of Pediatrics and more use of phototherapy than was observed in this study. To prevent extreme hyperbilirubinemia (> or =428 micromol/L [> or =25 mg/dL]) in 1 newborn, many newborns would need to receive these interventions.
Body temperature of newborns: what is normal?
Medical records of 203 healthy full-term infants were reviewed to determine the range of axillary temperatures for newborn infants, factors that affect temperature and nursery management of infants with temperatures outside published normal ranges. The mean birth temperature was 36.5 degrees C (S.D. = 0.6 degrees C). Temperature was associated with birth weight (p<0.0005) and the presence of maternal fever (p<0.0001) but not with type of environment or time of birth. The mean temperature increased with age, rising 0.2 degrees C by 2-3 hours after birth (p<0.0001) and 0.3 degrees C by 15-20 hours (p<0.0001). Among a subset of 114 eligible neonates the mean temperature dropped 0.2 degrees C after bathing (p<0.0001). Although 17% of all temperatures measured were in the hypothermic (< or =36.3 degrees C) range, the only response recorded by nursery staff consisted of warming by modifying the environment, e.g., bundling. Blood cultures were drawn from 51 infants (25%), 43 because of maternal intrapartum antibiotic treatment for maternal fever or prolonged duration of ruptured amniotic membranes (>24 hours) and none for evaluation of abnormal temperatures. No infants had systemic infections and all were discharged in stable condition. Newborn axillary temperatures in our nursery were considerably lower than what has been previously described as "normal." Given the frequency of "hypothermia" and absence of associated illness, we believe the reference range for newborn temperatures should be expanded to include lower temperatures.
Cholesterol screening in children and adolescents.
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Less aggressive treatment of neonatal jaundice and reports of kernicterus: lessons about practice guidelines.
The publication of guidelines calling for less aggressive treatment of jaundice in newborns has been followed by a reappearance of case reports of kernicterus. These case reports illustrate important issues for writers and consumers of practice guidelines. One issue is the particular salience of identified patients with bad outcomes, and their potentially disproportionate influence on decision-makers. A second issue is whether, when good evidence of treatment benefit is lacking, policymakers should recommend what has traditionally been done, recommend less treatment, or not make recommendations at all. Finally, the cases raise the question of whether treatment guidelines should be more conservative than their authors actually believe is necessary, to take into account the likelihood that they will not be closely followed. We believe that case reports can serve as an important early warning system, but policymakers should be aware of their potentially disproportionate influence. In the long run, patients and clinicians will be best served by guidelines that summarize and acknowledge the limitations of existing evidence, that allow a wide range of treatment options when evidence is weak, and that recommend what the guideline authors actually believe should be done. In the short run a period of readjustment may be required, however, as clinicians become accustomed to guidelines written to be followed, rather than bent.
Combination therapy for hepatitis C infection.
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Predicting hyperbilirubinemia in newborns: the importance of timing.
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Frequency of neonatal bilirubin testing and hyperbilirubinemia in a large health maintenance organization.
OBJECTIVE: To determine the frequency and interhospital variation of bilirubin testing and identified hyperbilirubinemia in a large health maintenance organization. DESIGN: Retrospective cohort study. SETTING: Eleven Northern California Kaiser Permanente hospitals. SUBJECTS: A total of 51,387 infants born in 1995-1996 at >/= 36 weeks' gestation and >/= 2000 g. MAIN OUTCOME MEASURE: Bilirubin tests and maximum bilirubin levels recorded in the first month after birth. RESULTS: The proportion of infants receiving >/= 1 bilirubin test varied across hospitals from 17% to 52%. The frequency of bilirubin levels >/= 20 mg/dL (342 micromol/L) varied from .9% to 3.4% (mean: 2.0%), but was not associated with the frequency of bilirubin testing (R(2) = .02). Maximum bilirubin levels >/= 25 mg/dL (428 micromol/L) were identified in.15% of infants and levels >/= 30 mg/dL (513 micromol/L) in .01%. CONCLUSIONS: Significant interhospital differences exist in bilirubin testing and frequency of identified hyperbilirubinemia. Bilirubin levels >/=20 mg/dL were commonly identified, but levels >/= 25 mg/dL were not.
Computed tomography of the appendix.
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Association between Cryptosporidium infection and animal exposure in HIV-infected individuals.
Cryptosporidium causes a debilitating illness in immunocompromised individuals, yet the source of sporadic Cryptosporidium infections is unknown. Because early cases of cryptosporidiosis were associated with animals, and pets are a source of companionship to individuals with AIDS, determination of the risk of cryptosporidiosis associated with pets is important. To assess this risk, we conducted a case-control study of HIV-infected individuals with and without cryptosporidiosis. No statistically significant difference in the rate of overall pet ownership, cat ownership, or bird ownership was found between the two groups. Dog ownership reached borderline statistical significance; 15 of 48 (31%) cases owned a dog, compared with 17 of 99 (17%) controls (odds ratio [OR] = 2.19; p = .05; 95% confidence interval [CI], 0.9-5.3). No statistically significant differences between cases and controls were found in the frequency of surface water ingestion, rural exposure, travel history, or contact with diarrheic individuals. Our findings indicate that pets do not represent a major risk factor for acquisition of Cryptosporidium for HIV-infected individuals. Whether dog ownership presents a minimal risk for cryptosporidiosis needs further investigation.
Urinary tract infection controversy and questions.
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Jaundice in full-term and near-term babies who leave the hospital within 36 hours. The pediatrician's nemesis.
There has been an increase in hyperbilirubinemia in the newborn population and, perhaps, an increase in bilirubin encephalopathy. The early discharge of newborns from hospital has made it necessary for us to reorient our thinking about bilirubin levels in the first 24 to 48 hours of life and alter our approach to follow-up. The pediatrician must evaluate and follow infants who have risk factors for the development of severe hyperbilirubinemia, paying particular attention to the breast-feeding, near-term infant.
Issues in studying the effectiveness of health services for children.
OBJECTIVES: To discuss issues in studying the effectiveness of health services for children, suggest areas in which more research is needed, and recommend strategies for future research. PRINCIPAL FINDINGS: Issues that should be considered include the choice of perspective, which will help determine the interventions studied and the measures of effectiveness and cost-effectiveness chosen. Unique challenges in this area include the fact that serious measurable morbidity is relatively uncommon in children, that causal relationships between services and outcomes may be difficult to establish, and that standard measures of cost-effectiveness may fail to accurately measure important benefits, such as reduced parental anxiety. More research is needed on high-risk and health-promoting behaviors, on critical parent behaviors, on classifying children by vulnerability status, on modes of delivery of preventive care, and on violence prevention. RECOMMENDATIONS: Group-randomized designs and observational research designs that take advantage of natural variations in practice may be increasingly useful in effectiveness studies. Parent- and patient-reported measures of health status and quality of life should be made briefer and more practical for routine use, and better measures of cost-effectiveness are needed. Future research efforts can best be supported by the concerted efforts of various constituencies, including health plans, providers, patients, researchers, and the government.
Evaluation of the erythrocyte sedimentation rate in children presenting with limp, fever, or abdominal pain.
An erythrocyte sedimentation rate (ESR) is commonly ordered as part of the evaluation of patients with nonspecific but potentially serious symptoms. To investigate the performance of ESR in this setting, we used a computerized database and medical chart review to identify children (n=299) with ESR done for a previously undiagnosed condition. Medical records were reviewed to determine symptoms at presentation, referral status, and subsequent diagnoses, which were classified as serious (n=93) or benign (n=206). We found that serious underlying disease was about 7 times as likely in patients with ESR>50 mm/hr (57/102) than in patients with ESR<20 mm/hr (7/89). Although the prevalence of serious disease was higher among referral patients, the likelihood ratios were similar for referral and primary-care patients. An erythrocyte sedimentation rate greater than 50 mm/hr was most informative in patients presenting with limp (likelihood ratio [LR] =8.2) and abdominal pain (LR=6.0) and least informative in patients presenting with fever (LR=2.5). On the other hand, an ESR<20 mm/hr is reassuring in patients presenting with fever (LR=0) or limp (LR=0.3), but not in patients presenting with abdominal pain (LR=0.8). An ESR between 20 and 50 mm/hr (23% of the patients) provided little information (LR 1.2-1.5) in each of the three groups. These results suggest that the ESR often provides useful information about the likelihood of serious illness among children presenting with worrisome but nonspecific symptoms, in particular in patients presenting with limp.
Carcinogenicity of lipid-lowering drugs.
OBJECTIVE: To review the findings and implications of studies of rodent carcinogenicity of lipid-lowering drugs. DATA SOURCES: Summaries of carcinogenicity studies published in the 1992 and 1994 Physicians' Desk Reference (PDR), additional information obtained from the US Food and Drug Administration, and published articles identified by computer searching, bibliographies, and consultation with experts. STUDY SAMPLE: We tabulated rodent carcinogenicity data from the 1994 PDR for all drugs listed as "hypolipidemics." For comparison, we selected a stratified random sample of antihypertensive drugs. We also reviewed methods and interpretation of carcinogenicity studies in rodents and results of clinical trials in humans. DATA SYNTHESIS: All members of the two most popular classes of lipid-lowering drugs (the fibrates and the statins) cause cancer in rodents, in some cases at levels of animal exposure close to those prescribed to humans. In contrast, few of the antihypertensive drugs have been found to be carcinogenic in rodents. Evidence of carcinogenicity of lipid-lowering drugs from clinical trials in humans is inconclusive because of inconsistent results and insufficient duration of follow-up. CONCLUSIONS: Extrapolation of this evidence of carcinogenesis from rodents to humans is an uncertain process. Longer-term clinical trials and careful postmarketing surveillance during the next several decades are needed to determine whether cholesterol-lowering drugs cause cancer in humans. In the meantime, the results of experiments in animals and humans suggest that lipid-lowering drug treatment, especially with the fibrates and statins, should be avoided except in patients at high short-term risk of coronary heart disease.