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Biomedical subjects

M S Kramer

Publications and source records attributed to M S Kramer.

At least 145 records · Page 8Linked to original sources
PubMed1988

Does breast feeding help protect against atopic disease? Biology, methodology, and a golden jubilee of controversy.

To help shed some light on the 50-year-old controversy concerning the possible protective effect of breast feeding on subsequent atopic disease, I developed 12 standards pertaining to both biologic and methodologic aspects of exposure (infant feeding), outcome (atopic conditions), and statistical analysis for studies of atopic eczema, asthma, allergic rhinitis, cow milk allergy, and other food allergy. Among the published studies on atopic eczema, the nine claiming a protective benefit of breast feeding performed less well than the 12 not making such a claim on "methodologic" standards relating to strict diagnostic criteria and blind ascertainment of outcome. The positive studies were somewhat stronger, however, on the "biologic" standards bearing on sufficient duration and exclusivity of breast feeding and on separate analysis of children at high risk. For the other atopic conditions, there were no important differences between positive and negative studies. In few negative or positive studies was there adequate control for confounding variables or examination of potential benefits relating to the severity or age at onset of atopic disease. To avoid another 50 years of unresolved controversy, future studies should improve both the biologic and methodologic aspects of their design and analysis.

Animals↗
PubMed1988

Parental diary of infant cry and fuss behaviour.

Despite their common use parental diaries of infants' cry and fuss behaviour have not been compared with objective methods of recording. To understand what is meant by the descriptions of crying and fussing in the diaries, the diaries of 10 mothers of 6 week old infants were compared with tape recordings of vocalisations made by the babies over a 24 hour period. There were moderately strong correlations between the frequency of episodes (clusters of 'negative vocalisations') on the audiotape and episodes of 'crying and fussing' in the diaries, and between the duration of episodes on the audiotape and episodes of 'crying' in the diaries. To assess the acceptability of the diaries for recording information for clinical and epidemiological research, they were then used in a population study of a wide socioeconomic group. Usable data were obtained from 91% of the sample. The results suggest that despite pronounced differences between recording methods, these diaries may provide valid and useful reports of crying and fussing in the short term.

Child Behavior↗
PubMed1987

Respiratory distress syndrome in second-born versus first-born twins. A matched case-control analysis.

The well-known increased risk of the respiratory distress syndrome in a twin born second as compared with the twin born first is usually attributed to the second twin's predisposition to depression at birth ("asphyxia"). We analyzed the etiologic roles of birth order, presentation, and depression at birth in the development of the respiratory distress syndrome in matched case-control populations drawn from 221 preterm twin pairs. Among the 39 twin pairs discordant for respiratory distress syndrome, the second twin was the affected member in 31 pairs. Second birth order was the only independent risk factor, but only in vaginal deliveries (matched odds ratio, 14.2; 95 percent confidence interval, 2.5 to 81.1). Second twins delivered abdominally did not have an increased risk relative to first twins (odds ratio, 0.9; confidence interval, 0 to 17.8). When depression at birth was evaluated as an outcome variable, malpresentation, rather than birth order, was the major risk factor (independent matched odds ratios of 2.7 [confidence interval, 1.0 to 7.5] and 1.3 [0.7 to 2.5], respectively). Thus, second twins' increased risk of respiratory distress syndrome cannot be explained by a predisposition to depression at birth; a more important factor may be that second twins do not benefit from the salutary effects of labor to the same extent as first twins.

Asphyxia Neonatorum↗
PubMed1987

Temporal variation in rates of cesarean section for dystocia: does "convenience" play a role?

The purpose of this study is to test the hypothesis that convenience for the physician plays a role in the rate of cesarean section performed because of dystocia. Three time periods were defined (night, 12 midnight to 7:59 AM; day, 8 AM to 5:59 PM; evening, 6 PM to 11:59 PM) based on the work commitments and daily routines of the obstetrician. Rates of cesarean section for dystocia were determined for each of the three time periods. An evening peak in the cesarean section rate is partially but not entirely explained by an evening increase in the proportion of patients in prolonged labor. When patients were stratified according to labor duration (less than 12, 12 to 15, and greater than 16 hours), a persistent evening excess in the rate of cesarean section for dystocia was observed for patients whose labor duration was less than 16 hours. Although this is interpreted as being consistent with the hypothesis of physician convenience, the magnitude of this effect on the overall rate of cesarean section for dystocia is small.

Cesarean Section↗
PubMed1987

Analgesic use, blood dyscrasias, and case-control pharmacoepidemiology. A critique of the International Agranulocytosis and Aplastic Anemia Study.

The International Agranulocytosis and Aplastic Anemia Study (IAAAS) of analgesic-induced risks of blood dyscrasias represents the current "state of the art" in case-control pharmacoepidemiology. We present a conceptual framework for examining the goal, methods, and analysis of an epidemiologic study of drug risks and review the IAAAS within this framework. In our view, the new risk estimates reported by the IAAAS are not inherently more accurate than existing ones, nor have they been measured in clinically and sociodemographically relevant groups of patients over the anticipated course of therapy. Thus, the reported risks cannot be used to guide clinical or regulatory decisions concerning available treatment options for such patients. Furthermore, we believe that the IAAAS methods for selection of cases and controls, ascertainment of exposure, and data analysis may well have led to invalid estimates even for those risks that are reported. We hope that closer attention to the conceptual framework we suggest and the methodologic issues we raise will enable future case-control pharmacoepidemiologic studies to provide more useful and accurate answers to questions concerning the adverse effects of drugs.

Agranulocytosis↗
PubMed1987

Toward an "unconfounded" classification of epidemiologic research design.

Existing classifications of research designs for epidemiologic studies are inconsistent and confusing because of the conceptual "confounding" of three distinct concepts: directionality in which exposure and outcome are investigated, sample selection criteria, and timing of the study proper with respect to the calendar times of exposure and outcome. The authors have attempted to construct a classification in which these three concepts comprise distinct (if not totally independent) axes. Closer attention to the distinctions described may help the planning and interpretation of epidemiologic studies, as well as facilitate future teaching and communication.

Cross-Sectional Studies↗
PubMed1987

Thrombotic complications of indwelling central catheters used for chronic hemodialysis.

A new double-lumen silicone-rubber dialysis catheter, designed to be placed surgically in central veins, is now available. There is little published data concerning the long-term use of this catheter for hemodialysis, but a review of the literature suggests that pericatheter thrombus formation with or without occlusion of major veins has been a complication of chronic central venous catheterization with a variety of catheters, in both dialysis and nondialysis settings. We had this catheter placed in four diabetic patients who had severe problems related to maintenance of adequate vascular access. Two of the four patients underwent venography within 3 months of catheter placement because of impaired catheter function and were found to have thrombi on the outside of their catheters. These thrombi could not be dissolved with fibrinolytic agents, and the catheters were removed surgically without incident. The other two patients have no radiologic evidence of thrombus formation 4 and 7 months, respectively, after catheter placement. We suggest that proper selection of patients for this type of vascular access should be the subject of future studies and that patients with malfunctioning catheters undergo venography to rule out the presence of significant catheter related thrombosis.

Adult↗
PubMed1987

Heparin free dialysis: comparative data and results in high risk patients.

Heparin free hemodialysis was compared to systemic heparinization, intermittent saline flushes and constant saline infusions in eight, stable chronic patients dialyzing on hollow-fiber artificial kidneys (HFAK) at blood flows of 250 to 300 ml/min. No significant differences in small molecule clearance, fluid removal or dialyzer clotting were noted. Since this data showed that heparin free hemodialysis without supplemental saline was feasible in a group of stable, chronic dialysis patients, we then prospectively studied twenty-nine patients judged to be at increased risk of hemorrhage from heparinization during 100 heparin-free dialyses. The incidences of severe and moderate dialyzer clotting were 7% and 20%, respectively. Seventeen of 27 treatments in which moderate or severe clotting occurred had identifiable factors thought to predispose to dialyzer clotting such as low blood flows, poor vascular-access function, severe hypotension and intradialytic blood transfusions. Although higher hematocrit values were associated with greater degrees of dialyser clotting, stepwise discriminant analysis employing blood flow, blood pressure, hematocrit and transfusion administration could not develop an accurate predictor or combination of predictors of clotting. No patient experienced de novo or increased bleeding and problems with inadequate dialysis were not observed. Since this method of heparin free dialysis is as safe and effective as previously reported strategies and requires no specialized equipment or procedures, it is a reasonable initial strategy for dialyzing high risk patients.

Acute Kidney Injury↗
PubMed1987

Diethylstilbestrol-related clear-cell adenocarcinoma in women with initial examinations demonstrating no malignant disease.

The DES Screening Center of Queens, Nassau, and Suffolk counties has screened approximately 2000 diethylstilbestrol (DES)-exposed women since its inception in 1979. Four women, who at their initial visit were noted to have only nonmalignant DES-related changes, subsequently developed clear-cell adenocarcinoma while under observation, between 18-81 months after their first colposcopy. The age at diagnosis ranged from 16-31. Three patients had been receiving close follow-up; one had not. These cases emphasize the need for frequent follow-up for these patients using careful inspection and palpation, vaginal and cervical cytology, colposcopy, and colposcopically directed biopsy of suspicious areas.

Adenocarcinoma↗
PubMed1987

Intrauterine growth and gestational duration determinants.

Despite the general recognition that low birth weight can be caused by many factors, confusion and controversy remain about which factors have independent causal effects, as well as the quantitative importance of those effects. Previous research findings have often been conflicting because of a failure to distinguish intrauterine growth retardation from prematurity, differences in focus (means v rates), inadequate control for confounding variables, and insufficient statistical power. This review of the English and French language medical literature published between 1970 and 1984 is based on a critical assessment and meta-analysis of 895 studies concerning 43 potential determinants of intrauterine growth or gestational duration. Based on methodologic standards established a priori for each candidate determinant, the best studies were used to assess the existence and magnitude of an independent causal effect on birth weight, gestational age, prematurity, and intrauterine growth retardation. Factors with well-established direct causal impacts are identified, and their relative importance is indicated for "typical" developing and developed country settings. Modifiable factors with large effects are targeted for public health intervention in the two settings. Finally, factors of potential quantitative importance, but for which data are either unavailable or inconclusive, are highlighted as priorities for future research.

Body Weight↗