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D Zucker

Publications and source records attributed to D Zucker.

At least 19 recordsLinked to original sources
PubMed2001

The great tocolytic debate: some pitfalls in the study of safety.

The controversy surrounding the use of tocolytic agents has been raging for decades. Tocolytic drugs play a pivotal role in the prevention of preterm birth, which is the major cause of neonatal morbidity and mortality. Studies on the efficacy and safety of these drugs are of the utmost importance to many disciplines within the medical community. Unfortunately, many clinical decisions regarding tocolytic agents are based on incorrect information resulting from flawed studies. In this article we discuss the major design flaws common to many studies of tocolytic safety and in so doing explain some of the conflicting evidence regarding safety. Each of the two major types of study designs, preterm birth retrospective studies and prospective randomized trials, is associated with a serious flaw. Retrospective preterm birth studies give misleading and inconclusive results to the question of safety because of the use of incomplete cohorts. The inadequately sized prospective studies in the current literature lack the power to detect important clinical differences.

Cerebral Hemorrhage↗
PubMed2000

Florida's "truth" campaign: a counter-marketing, anti-tobacco media campaign.

The "truth" campaign was created to change youth attitudes about tobacco and to reduce teen tobacco use throughout Florida by using youth-driven advertising, public relations, and advocacy. Results of the campaign include a 92 percent brand awareness rate among teens, a 15 percent rise in teens who agree with key attitudinal statements about smoking, a 19.4 percent decline in smoking among middle school students, and a 8.0 percent decline among high school students. States committed to results-oriented youth anti-tobacco campaigns should look to Florida's "truth" campaign as a model that effectively places youth at the helm of anti-tobacco efforts.

Adolescent↗
PubMed1999

Internal pilot studies I: type I error rate of the naive t-test.

When sample size is recalculated using unblinded interim data, use of the usual t-test at the end of a study may lead to an elevated type I error rate. This paper describes a numerical quadrature investigation to calculate the true probability of rejection as a function of the time of the recalculation, the magnitude of the detectable treatment effect, and the ratio of the guessed to the true variance. We consider both 'restricted' designs, those that require final sample size at least as large as the originally calculated size, and 'unrestricted' designs, those that permit smaller final sample sizes than originally calculated. Our results indicate that the bias in the type I error rate is often negligible, especially in restricted designs. Some sets of parameters, however, induce non-trivial bias in the unrestricted design.

Bias↗
PubMed1997

An application of the Zucker-Wittes modified ratio estimate statistic in the Post Coronary Artery Bypass Graft (CABG) clinical trial.

In the Post Coronary Artery Bypass Graft (POST CABG) clinical trial, the primary outcome is substantial worsening (i.e., narrowing of the lumen diameter) of the vein grafts upon comparison of the baseline and follow-up angiograms. The patients had one to five non-occluded vein grafts at entry, so there may be from one to five primary outcome responses per patient. A modified ratio estimate (MRE) statistic, as described previously by Zucker and Wittes, may be used to analyze data of this kind. In the present paper we propose a more powerful MRE statistic when the event rates and/ or intraclass correlations vary according to number of grafts per patient. We also adapt this statistic to the factorial treatment design of the POST CABG clinical trial.

Anticholesteremic Agents↗
PubMed1997

Differences in quality of life among patients receiving dialysis replacement therapy at seven medical centers.

The purpose of this study is to investigate the variations in quality of life (QOL) among patients with end-stage renal disease (ESRD) who are receiving replacement therapy in several dialysis centers. This observational study includes interviews with nurses and data extraction from medical charts for all 680 adults who had been on dialysis therapy for more than 4 weeks in seven dialysis centers. By using multivariate analysis, we generated a model to explain the variance in QOL as measured by the QL index score (developed by Spitzer et al., J Chronic Dis 1981; 34:585-597) among patients pooled from all centers. The expected mean QL index score and 95% confidence interval were computed for each dialysis center. Centers with observed mean QL index scores outside of the expected confidence range were marked as possible outliers. We found the following patient attributes to be independently associated with QOL: age, education, occupation, and certain comorbidities (e.g., diabetes, stroke). After adjustment for case mix, we could identify four outlier centers. After further adjustment for albumin in serum, a possible process indicator, two centers were no longer considered as outliers. These findings indicate that the variance in QOL of ESRD patients at different centers is not entirely explained by known case-mix factors. Further research should explore whether such variations are related to dissimilarity in the process of care at different centers.

Aged↗
PubMed1996

Method for separating patient and procedural factors while analyzing interdepartmental differences in rates of surgical infections: the Israeli Study of Surgical Infection in Abdominal Operations.

The objective of this study was to develop a method for analyzing differences in the performance of hospitals with respect to outcome by separating patient factors from procedural factors. The setting included a prospective follow-up of a sample of 5571 patients undergoing all types of surgical procedures in general surgery departments of 11 hospitals (20 surgical departments) across Israel. Of these, 769 underwent surgery involving the opening of the bowel, and they are the subjects of this report. Our method consisted of a prospective follow-up by a nurse epidemiologist, including detailed clinical data from the day of admission to hospital discharge. Analysis was directed at identifying reasons for the observed variability in wound infections among departments. Observed rates were compared with "expected" rates calculated from a logistic model pooled over departments. An attempt was made to separate patient-inherent characteristics, such as age, sex, and diagnosis, from procedural factors, depicting the patient's experience during his hospitalization. Results indicated that the marked interdepartmental differences in the observed infection rates were not accounted for by differences in the "case mix" among departments. Procedural risk factors in this data set played the main role in explaining the observed variability among surgical departments. We conclude that the simple method presented here used the data pooled over departments to define the main risk determinants for infection in this data set. It separated intrinsic patient factors from procedural characteristics, and could be used in studies where the main interest is to compare institutions, and point at reasons behind the differences in outcomes.

Adult↗
PubMed1994

Ten-year results of the randomized control trials of coronary artery bypass graft surgery: tabular data compiled by the collaborative effort of the original trial investigators. Part 2 of 2.

This metaanalysis has some important general implications for conducting studies to evaluate other treatments as well as for patient management. To avoid missing clinically important differences (eg, 15-20% differences in mortality at 5 years) between the methods of revascularization, study populations should be several times larger than those in our metaanalysis, should include a high proportion of the types of patients for whom surgery is known to be superior to medical therapy, and should be complemented by a systematic overview. We recommend that researchers running large randomized trials consider prospective collaboration with researchers from other trials with a common protocol.

Adult↗
PubMed1994

Ten-year results of the randomized control trials of coronary artery bypass graft surgery: tabular data compiled by the collaborative effort of the original trial investigators. Part 1 of 2.

OBJECTIVE: To make available 10-year mortality data compiled and analyzed on patients with stable coronary heart disease (angina not severe enough to necessitate surgery) from all studies in which patients were randomized to initial coronary artery bypass graft (CABG) surgery or initial medical treatment and to determine whether the effects are influenced by the extent of coronary artery disease and degree of left-ventricular function. Data and analyses are presented in tabular form; text is published simultaneously in Lancet. METHODS: We collected individual patient data using standardized forms and, whenever possible, uniform definitions. We used Mantel-Haentel methods to combine data. Restricted means analyses were applied to quantify the extension in survival, and logistic regression analyses were applied to assess whether any baseline covariate affected the treatment differences. RESULTS: Of 2,649 patients, 1,324 were assigned to receive CABG surgery and 1,325 to the medical group. Mean age was 50.8 years; 98.8% were men. 93.7% of the CABG group underwent surgery. 25% of the medical group had undergone surgery at 5 years, 33% at 7 years, and 41% at 10 years. Initial CABG surgery reduced mortality significantly at 5 years (10.2% vs 15.8%; OR = 0.61; P < 0.001), 7 years (15.8% vs 21.7%; OR = 0.68; P < 0.001), and 10 years (26.4% vs 30.5%; OR = 0.83; P < 0.03). Risk reductions were most pronounced in patients with left-main disease compared to those with 3- or 1-2-vessel disease (at 5 years OR = 0.32, 0.58, and 0.77, respectively). CONCLUSIONS: Initial CABG surgery compared to initial medical management reduces mortality, especially in high- and medium-risk patients.

Adult↗
PubMed1994

Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration.

We carried out a systematic overview using individual patient data from the seven randomised trials that have compared a strategy of initial coronary artery bypass graft (CABG) surgery with one of initial medical therapy to assess the effects on mortality in patients with stable coronary heart disease (stable angina not severe enough to necessitate surgery on grounds of symptoms alone, or myocardial infarction). 1324 patients were assigned CABG surgery and 1325 medical management between 1972 and 1984. The proportion of patients in the medical treatment group who had undergone CABG surgery was 25% at 5 years, 33% at 7 years, and 41% at 10 years: 93.7% of patients assigned to the surgery group underwent CABG surgery. The CABG group had significantly lower mortality than the medical treatment group at 5 years (10.2 vs 15.8%; odds ratio 0.61 [95% CI 0.48-0.77], p = 0.0001), 7 years (15.8 vs 21.7%; 0.68 [0.56-0.83], p < 0.001), and 10 years (26.4 vs 30.5%; 0.83 [0.70-0.98]; p = 0.03). The risk reduction was greater in patients with left main artery disease than in those with disease in three vessels or one or two vessels (odds ratios at 5 years 0.32, 0.58, and 0.77, respectively). Although relative risk reductions in subgroups defined by other baseline characteristics were similar, the absolute benefits of CABG surgery were most pronounced in patients in the highest risk categories. This effect was most evident when several prognostically important clinical and angiographic risk factors were integrated to stratify patients by risk levels and the extension of survival at 10 years was examined (change in survival -1.1 [SE 3.1] months in low-risk group, 5.0 [4.2] months in moderate-risk group, and 8.8 [5.4] months in high-risk group; p for trend < 0.003). A strategy of initial CABG surgery is associated with lower mortality than one of medical management with delayed surgery if necessary, especially in high-risk and medium-risk patients with stable coronary heart disease. In low-risk patients, the limited data show a non-significant trend towards greater mortality with CABG.

Adult↗
PubMed1992

Testing the effect of treatment in experiments with correlated binary outcomes.

This paper considers the problem of testing for treatment effect in a randomized experiment with correlated binary outcomes, representing success or failure for different "parts" of a randomized unit. Attention is restricted to tests that are based on a summary score for each individual randomized, and thus are valid regardless of the precise nature of the correlation among parts. The focus is on the efficiency of such tests under various correlation structures, with special emphasis on the case in which the correlation among parts within an individual differs across treatment groups. A class of summary score statistics is defined, and optimal testing is discussed for some simple situations. Three potential general-purpose tests also are described: (1) the ratio estimate test discussed by Henderson et al. (1988, Controlled Clinical Trials 9, 189-205); (2) a modified ratio estimate test with adjusted weighting based on the within-individual correlation between parts; (3) a test defined by applying the Mantel-Haenszel procedure to the proportion of individuals with at least one failure, stratifying by the number of parts. For these general-purpose tests, numerical calculations of asymptotic efficiency are presented under a wide range of designs and correlation structures. On the basis of these results, some practical recommendations for choosing a test are made.

Humans↗
PubMed1989

Cognitive aspects of panic attacks. Content, course and relationship to laboratory stressors.

Twenty patients with panic attacks and ten controls were given a standardised interview about thoughts occurring during times of anxiety or panic attacks. The interviewer was blind to the subject's diagnosis. The 20 panic patients underwent a psychophysiological test battery which included a cold pressor test, mental arithmetic task, and 5.5% CO2 inhalation. More patients than controls reported thoughts centered on fears of losing control and shame when anxious. Panic patients rated their thoughts as stronger and clearer than did controls and they had more difficulty excluding them from their minds. A feeling of anxiety preceded anxious thoughts in patients. This suggests that 'faulty cognitions' are not the initial event in a panic attack, although anxious thoughts may exacerbate or maintain them. Significant correlations were found between the intensity of anxiety-related thoughts in anticipation of mental arithmetic and changes in diastolic blood pressure and heart rate during mental arithmetic.

Adult↗
PubMed1988

Clinical stages of dementia and the dexamethasone suppression test.

1. This study was undertaken to evaluate the relationship between clinical aspects of primary degenerative dementia and suppression or non-suppression in the dexamethasone suppression test. 2. We studied 34 male patients with primary degenerative dementia (as diagnosed by DSM-III criteria). Dexamethasone 1 mg p.o. was administered at 11:00 PM and blood was drawn for cortisol determination at 4:00 PM the next day. 3. CLINICAL FACTORS INCLUDED: age, age at onset, duration of dementia, history of psychiatric illness, severity as measured by Global Deterioration Scale (GDS) score, and "malignancy" of dementia (rated by years of onset to institutionalization and as a ratio of Global Deterioration Scale to duration of primary degenerative dementia). 4. RESULTS: 56% of primary degenerative dementia patients failed to suppress. The highest degree of non-suppression was seen in Global Deterioration Scale 5 and 6 subjects (Table). 5. An unexpected finding was that a large number of Global Deterioration Scale 7 patients demonstrated normal post-dexamethasone suppression of the hypothalamic-pituitary-adrenal axis. 6. Some contradictions in previously reported studies may be explained by this pattern.

Aged↗
PubMed1988

Human monoamine oxidase gene (MAOA): chromosome position (Xp21-p11) and DNA polymorphism.

An essentially full-length cDNA clone for the human enzyme monoamine oxidase type A (MAO-A) has been used to determine the chromosomal location of a gene encoding it. This enzyme is important in the degradative metabolism of biogenic amines throughout the body and is located in the outer mitochondrial membrane of many cell types. Southern blot analysis of PstI-digested human DNA revealed multiple fragments that hybridized to this probe. Using rodent-human somatic cell hybrids containing all or part of the human X chromosome, we have mapped these fragments to the region Xp21-p11. A restriction fragment length polymorphism (RFLP) for this MAOA gene was identified and used to evaluate linkage distances between this locus and several other loci on Xp. The MAOA locus lies between DXS14 and OTC, about 29 cM from the former.

Alleles↗
PubMed1988

Increase in tryptophan oxygenase activity in alcoholic patients.

This study was conducted in order to assess whether chronic excessive alcohol consumption affects the activity of the liver enzyme tryptophan oxygenase which is rate limiting along the most important pathway of tryptophan catabolism. Five alcoholics were studied twice, once shortly after admission to an inpatient unit and the second time 1 month later. On each study day patients were given a tryptophan load of 50 mg/kg. Kynurenine in the urines (which reflects tryptophan oxygenase activity) was measured for a period of 6 hr following the load and showed a significantly enhanced activity of the enzyme shortly after cessation of drinking. This increased activity could explain the lowered tryptophan levels we have previously reported in alcoholics. The increase in enzyme activity may have been mediated by a rise in glucocorticoid hormones. In all instances, plasma cortisol measured hourly for 6 hr after the start of the experiment, was higher shortly after cessation of drinking than 1 month later.

Adult↗
PubMed1985

Association between amino acid alterations and hallucinations in alcoholic patients.

Because available evidence suggests that alterations in the serotonergic as well as dopaminergic tones underlie hallucinatory activity, we decided to investigate whether serotonin and dopamine pathways are modified in alcoholics with a history of hallucinosis. Brain serotonin has been shown to depend on the plasma ratio of its precursor tryptophan over other amino acids competing with it for brain entry. Similarly, brain dopamine depends on the plasma ratio of its precursors phenylalanine and dopamine over their competitors. Amino acid abnormalities are common in alcoholics. For this reason, we assessed whether alcoholics who had experienced hallucinations have alterations in amino acids believed to be associated with neurotransmitter modifications. Patients with a history of hallucinations were found to have a tryptophan ratio significantly lower than that of patients without such a history, and a tyrosine + phenylalanine ratio significantly higher. These data suggest that amino acid abnormalities believed to result in decreased brain serotonin and in increased brain dopamine render certain individuals more vulnerable to hallucinatory experiences.

Adult↗