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Biomedical subjects

M S Kramer

Publications and source records attributed to M S Kramer.

At least 109 records · Page 6Linked to original sources
PubMed1994

Diagnosis and treatment of cytomegalovirus disease in pediatric renal transplant recipients.

The purpose of this study was to identify factors associated with the development of cytomegalovirus (CMV) disease and to assess the morbidity of this illness in pediatric renal transplant patients. The authors retrospectively reviewed the records of 135 patients (< 18 years of age) who underwent a total of 151 transplants (146 kidney transplants, five kidney/liver transplants) over 5 years (average follow-up period, 33.0 +/- 21.7 months). They assessed the risk factors that previously have been associated with the development of CMV disease in adults (age, occurrence of acute rejection episodes, and preoperative donor and recipient CMV serological status) and evaluated the incidence of associated graft loss and mortality. Twenty-two episodes of CMV disease were diagnosed based on evidence of CMV infection and on clinical symptoms; the episodes were treated in 17 patients. A multivariate analysis showed that the development of CMV disease was associated with age of > or = 13 years (P = .02), concomitant liver transplantation (P = .01), and treatment of acute rejection (P = .04). In addition, patients who were CMV-seronegative preoperatively and received a graft from a CMV-seropositive donor (P = .04) or who were CMV-seropositive preoperatively and received a graft from a CMV-seronegative donor (P = .02) were more likely to have CMV disease. Although all patients with CMV disease required hospitalization and were treated with intravenous ganciclovir, CMV disease was not associated with increased allograft loss or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Urine testing in young febrile children: a risk-benefit analysis.

OBJECTIVE: To assess the relative risks and benefits of 10 potential urine testing strategies (compared with no testing) involving urinalysis and urine culture for children aged 3 to 24 months with fever but no focus of bacterial infection. DESIGN: Decision analysis based on the literature. The 10 testing strategies consist of five pairs; within each pair of strategies, one calls for urinalysis and urine culture of a clean-voided (bag) specimen, and urine culture, and in the other, the urine specimen is sent for culture only if the result of the urinalysis is abnormal. The five pairs differ in selectivity for testing: all children, girls only, temperature > or = 39 degrees C only, fever only (no respiratory or gastrointestinal symptoms), or temperature > or = 40 degrees C only. The results of the decision analysis are expressed as the preventive fraction (the proportion of cases prevented) for end-stage renal disease (ESRD) and hypertension, and as two risk/benefit (RB) ratios: the number of children tested per case of ESRD prevented (RB1), and the number of children with false-positive diagnosis and treatment of urinary tract infection per case of ESRD prevented (RB2). RESULTS: On the basis of the available evidence, none of the testing strategies succeeds in preventing the majority of cases of ESRD and hypertension (preventive fraction = 0.10 to 0.50), and all are associated with high ratios of children tested (RB1 = 4167 to 12,500) and false-positive diagnosis and treatment (RB2 = 563 to 1800) per case of ESRD prevented. A strategy of combined urinalysis and urine culture in children with temperature > or = 39 degrees C is associated with the most favorable RB profile: preventive fraction = 0.45, RB1 = 5556; RB2 = 776. Sensitivity analyses indicate that the relative ranking of the strategies is relatively robust in regard to alterations in the estimates of the sensitivity or specificity of the urinalysis, the relative risk of renal scarring associated with delayed diagnosis and treatment, and the risk of scarring-induced hypertension or ESRD. CONCLUSIONS: Up to 50% of the long-term sequelae of occult urinary tract infections in young febrile children appear preventable by urine testing, but even the most favorable strategies require testing of thousands of children, and unnecessarily treating hundreds, for every case prevented. Our analysis reveals those strategies with more favorable RB profiles and emphasizes the need for rapid and convenient urine tests with much higher sensitivity and specificity or the need for less aggressive management strategies for febrile infants and young children with urinary tract infection.

Anti-Bacterial Agents↗
PubMed1994

Parents' versus physicians' values for clinical outcomes in young febrile children.

OBJECTIVE: To compare how parents and physicians value potential clinical outcomes in young children who have a fever but no focus of bacterial infection. METHODS: Cross-sectional study of 100 parents of well children aged 3 to 24 months, 61 parents of febrile children aged 3 to 24 months, and 56 attending staff physicians working in a children's hospital emergency department. A pretested visual analog scale was used to assess values on a 0-to-1 scale (where 0 is the value of the worst possible outcome, and 1 is the value for the best) for 22 scenarios, grouped in three categories according to severity. Based on the three or four common attributes comprising the scenarios in a given group, each respondent's value function was estimated statistically based on multiattribute utility theory. RESULTS: For outcomes in group 1 (rapidly resolving viral infection with one or more diagnostic tests), no significant group differences were observed. For outcomes in groups 2 (acute infections without long-term sequelae) and 3 (long-term sequelae of urinary tract infection or bacterial meningitis), parents of well children and parents of febrile children had values that were similar to each other but significantly lower than physicians' values for pneumonia with delayed diagnosis, false-positive diagnosis of urinary tract infection, viral meningitis, and unilateral hearing loss. For bacterial meningitis with or without delay, however, the reverse pattern was observed; physicians' values were lower than parents'. In arriving at their judgment for group 2 and 3 scenarios, parents gave significantly greater weight to attributes involving the pain and discomfort of diagnostic tests and to diagnostic error, whereas physicians gave significantly greater weight to attributes involving both short- and long-term morbidity and long-term worry and inconvenience. Parents were significantly more likely to be risk-seeking in the way they weighted the attributes comprising group 2 and 3 scenarios than physicians, ie, they were more willing to risk rare but severe morbidity to avoid the short-term adverse effects of testing. CONCLUSIONS: Parents and physicians show fundamental value differences concerning diagnostic testing, diagnostic error, and short- and long-term morbidity; these differences have important implications for diagnostic decision making in the young febrile child.

Attitude of Health Personnel↗
PubMed1993

Diagnostic test ordering in the evaluation of febrile children. Physician and environmental factors.

OBJECTIVE: To assess the independent effects of physician and environmental factors on test ordering. METHODS: We prospectively studied 6191 consecutive visits by nonadmitted febrile (rectal temperature > or = 38.0 degrees C) children less than 18 years of age to a children's hospital emergency department from March through November 1989. Multiple logistic regression analysis was used to control for the mutually confounding effects of patient, physician, and environmental factors and to assess attending staff-trainee interactions (effect modification). RESULTS: Patients evaluated by hospital-based subspecialists were significantly more likely to undergo tests than patients evaluated by community-based physicians (odds ratio [OR] for undergoing at least one test, 1.13; 95% confidence interval [CI], 1.04 to 1.23; OR for complete blood cell count, 1.28; 95% CI, 1.12 to 1.46). Children seen by physicians with more than 10 years of experience were significantly less likely to undergo tests than those seen by their more junior colleagues, but this effect was modified substantially by trainee presence and level. For example, when children were seen by a physician with more than 10 years of experience and no trainee was involved, the OR for undergoing at least one test was 0.81 (95% CI, 0.73 to 0.91). If the same physician saw the same patient with a junior trainee, the OR for undergoing at least one test was 1.08 (95% CI, 0.95 to 1.24). Patients seen between July and November were significantly more likely to undergo at least one test than those seen between March and June (OR, 1.28; 95% CI, 1.20 to 1.36). CONCLUSIONS: Attending staff, trainee, and seasonal effects on test ordering have important implications for febrile children and their families, for clinical training and supervision, and for health care costs.

Adolescent↗
PubMed1993

Terminal digit preference, random error, and bias in routine clinical measurement of blood pressure.

We examined the presence, magnitude, and consequences of systematic and random errors caused by terminal digit preference in the measurement of highest systolic blood pressure during prenatal visits in 28,841 non-referred pregnant women who delivered between 1 January 1982 and 31 March 1990. In the overall distribution of terminal digit readings, 78% were read to 0, 15% to even digits other than 0, 5% to 5, and only 2% to odd digits other than 5. This preference for 0's was consistent across the entire distribution of blood pressure and for a variety of maternal characteristics. The relative frequency of the cutoff value of 140 mmHg (i.e. the percentage of readings on 140 mmHg) within the range containing the value (i.e. 138-142 mmHg) was similar to the relative frequency of other multiples of 0. This was true whether the comparison was made in the overall study sample, or in a pre-selected low-risk subgroup or high-risk subgroup, indicating no systematic bias. On the other hand, a strong tendency to read blood pressure values to the nearest 0 had a marked effect on the classification of hypertension. Changing the definition of hypertension from > or = 140 mmHg to > 140 mmHg produced a reduction in prevalence of hypertension from 25.9 to 13.3% in the overall study sample, from 15.4 to 6.3% in the low-risk subgroup, and from 43.3 to 25.3% in the high-risk subgroup. Epidemiologic studies that compare prevalences of hypertension in different populations based on routine clinical measurement of blood pressure and a single cutoff point should assess the consequences of terminal digit preference in defining hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Bias↗
PubMed1993

Relapse following emergency treatment for acute asthma: can it be predicted or prevented?

We prospectively followed 314 children discharged from a children's hospital emergency department (ED) following an asthma attack, to identify risk, factors for relapse, i.e. a second ED visit for asthma within the next 10 days. Parents were surveyed concerning their child's past medical history, drugs received prior to the index visit, triggering factors, physician availability, parental anxiety, and sociodemographic variables. Data on severity of the attack, emergency treatment, response to treatment and drugs prescribed on discharge were extracted from the medical record. Ninety-six of the 314 children (31%) relapsed, most (68%) within 24 hours. Using multiple logistic regression, a predictive model was developed on 211 patients ("test sample"). The best model contained two variables: (1) the number of ED visits for acute asthma in the previous year (odds ratio [OR] = 2.4 for 4 or more vs fewer visits, 95% CI = 1.3-4.4) and (2) the intake of an oral short-acting theophylline preparation during the course of the acute treatment (OR = 0.4, 95% CI = 0.2-0.7). The sensitivity, specificity and positive predictive values of this model for predicting relapse were 73, 53, and 40%, respectively. When applied to a second randomly selected "validation sample" of 103 children, sensitivity was 73%, specificity 50%, and PPV 41%, thus indicating the stability of the model. The model identifies the number of ED visits in the previous year as an important risk factor for relapse. It also suggests that oral short-acting theophylline may still have a role in the treatment of patients in whom the contribution of inflammation to airway obstruction is minimal.

Acute Disease↗
PubMed1993

Role of the complete blood count in detecting occult focal bacterial infection in the young febrile child.

Previous studies of the value of the complete blood count (CBC) in distinguishing viral from bacterial infection in young febrile children have failed to exclude children with clinically evident bacterial infection and thus have inflated the positive predictive value of the test for occult focal infection. We prospectively studied 2492 children 3-24 months of age who presented to a children's hospital emergency department between March 1989 and August 1990 with fever (> or = 38.0 degrees C) of acute (< or = 4 days) onset but no evident bacterial focus of infection, 433 (17.4%) of whom received a CBC. We also carried out an 8-year retrospective analysis to estimate prior, or pre-test, probabilities (prevalences) and examine CBC results for rare occult bacterial infections (meningitis, osteomyelitis, and septic arthritis). Estimated prior probabilities for the four most common categories of infection that can be diagnosed at the initial visit were: non-pneumonitic viral infection, 88.6% in boys and 86.0% in girls; pneumonia, 8.5% in both sexes; urinary tract infection (UTI), 3.0% in boys and 5.5% in girls; and bacterial meningitis, 0.0066% in both sexes. The likelihood (sensitivity) of a total white blood cell (WBC) count > or = 15,000/mm3 was 25.5, 64.5, 62.5, and 50.0% for viral infection, pneumonia, UTI, and meningitis, respectively. Among children with a high total white blood cell count, neither a total polymorphonuclear count > or = 10,000/mm3 nor a band count > or = 500/mm3 was associated with significantly elevated likelihoods for occult pneumonia or UTI, a finding confirmed by multiple logistic regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

Effects of energy and protein intakes on pregnancy outcome: an overview of the research evidence from controlled clinical trials.

This overview summarizes the evidence from controlled clinical trials bearing on the effects of energy and protein intakes during gestation on the outcome of pregnancy, based on meta-analyses of reports contained in the Oxford Database of Perinatal Trials. Trials of nutritional advice to increase energy and protein intakes, and of balanced energy and protein supplementation, have demonstrated only modest increases in maternal weight gain and fetal growth, even in undernourished women, and no long-term benefits to the child in terms of growth or neurocognitive development. Neither balanced isoenergetic protein supplementation nor high-protein supplementation appears beneficial to either mother or infant and may even impair fetal growth. The same can be said for energy and protein restriction in pregnant women who are overweight or exhibit high weight gain. Future trials should concentrate on prevention of preterm birth and fetal and neonatal death; such trials will require substantially larger sample sizes than those used in the past.

Energy Intake↗
PubMed1993

Stimulation of nonspecific immunity to reduce the risk of recurrent infections in children attending day-care centers. The Epicrèche Research Group.

A randomized, double blind, placebo-controlled clinical trial was performed in 423 children attending day-care centers to assess whether stimulating nonspecific immunity would reduce the incidence of recurrent infections. The drug used for the trial (Imocur) is an extract obtained from eight different species of bacteria. At the end of the total follow-up period (3 months with treatment and 4.5 months without), the risk for > or = 4 episodes of upper respiratory infections was not significantly lower in the treated group than in the placebo group (26.7% vs. 33.8%, relative risk, 0.79; 95% confidence interval, 0.59 to 1.06). In an exploratory analysis limited to the 3-month treatment period, however, we observed a 48% reduction in the risk of presenting > or = 3 episodes of upper respiratory infections: 9.5% vs. 18.3%, respectively, in the treatment group and the placebo group (relative risk, 0.52; 95% confidence interval, 0.31 to 0.86). Similar results were found for the risk of > or = 1 episode of gastroenteritis. We also observed a strong correlation between the drug efficacy and age; this observation is coherent with the underlying pathophysiologic model in which the immune system matures with age.

Adjuvants, Immunologic↗
PubMed1992

Maternal nutrition and spontaneous preterm birth.

Previous studies suggesting that maternal undernutrition increases the risk of preterm birth have suffered from several methodological shortcomings, including use of total gestational weight gain rather than net rate of gain in maternal tissue, inclusion of induced preterm deliveries, and error-prone gestational age measurements based solely on menstrual dates. The authors have attempted to overcome these shortcomings by investigating the potential etiologic roles of prepregnancy body mass index, net rate of maternal weight gain, height, and a number of other potential biological and sociodemographic determinants of spontaneous (i.e., noninduced) preterm birth in a cohort of 13,102 women with early ultrasound-confirmed gestational age who delivered at the Royal Victoria Hospital in Montreal, Quebec, Canada, between January 1, 1980 and March 31, 1989. Total weight gain, but not body mass index, was highly significantly associated with spontaneous preterm birth, averaging 14.6, 12.5, 9.9, and 9.1 kg, in women delivering at 37 or more, less than 37, less than 34, and less than 32 completed weeks, respectively. Although the relation persisted when weight gain was expressed as an overall rate, it disappeared when the analysis was based on net rate; mean net rates of gain were 0.28, 0.29, 0.27, and 0.27 kg/week, respectively. On the basis of multiple logistic regression analyses, significant determinants of birth at less than 37 weeks included maternal short stature; noncompletion of high school; unmarried status; smoking; diabetes; urinary tract infection within 2 weeks of delivery; prepregnancy hypertension; severe pregnancy-induced hypertension; and previous history of preterm delivery, low birth weight, or neonatal death. Most of these factors retained their significance for birth at less than 34 and less than 32 weeks. In fact, the effect of low maternal education was even stronger at these more severe "levels" of preterm birth. The authors conclude that prepregnancy weight-for-height and gestational weight gain are not important determinants of spontaneous preterm birth and that some previous studies have mistaken an effect of shortened gestation for its cause. Other biologic and social determinants, however, indicate priorities for future research and intervention.

Adult↗
PubMed1992

Causal propositions in clinical research and practice.

The concept of causation is central to clinical research and practice. The health science literature on causality, largely contributed by epidemiologists, has examined the population-based question of whether an exposure can cause a given health outcome. Most of this literature has focused on criteria for assessing causality, rather than attempting to define it. Moreover, the population-based approach is rather distant from the individual persons in whom causes must act, which has led to different perspectives on causality among epidemiologists and health policy markers, on the one hand, and clinical practitioners and the lay public, on the other. We attempt to bridge the gap between these perspectives by defining three probabilistic causal propositions based on the locus (individual vs population) and time frame (past vs future outcome) to which they refer, beginning with the individual in whom a health outcome has already occurred ("retrodictive" causal propositions, i.e. It Did) and proceeding to "potential" causal propositions (It Can) for populations and "predictive" causal propositions (It Will) for individuals or populations. We conclude by showing how attention to these distinctions may help avoid common pitfalls that can impair clinical or public health decision-making.

Causality↗
PubMed1992

Bias and 'overcall' in interpreting chest radiographs in young febrile children.

Few studies have examined the diagnostic validity of the examination physician's interpretation of chest radiographs in young febrile children, and none (to our knowledge) the extent to which the "official" (ie, the radiologist's) reading may be biased by access to the examining physician's reading and to other clinical information. The authors studied 287 consecutive chest radiographs obtained in 286 febrile children 3 to 24 months of age without chronic cardiopulmonary disease or known asthma who presented to a children's hospital emergency department between March 1989 and August 1990. The readings by treating pediatricians, official pediatric radiologists, and a "blind" pediatric radiologist were compared. Official radiologists had access to the treating pediatricians' readings and the clinical information provided on the radiography requisition. The blind radiologist knew only that each child was 3 to 24 months of age and febrile, and he was asked to judge the presence or absence of pneumonia. Using the blind radiologist's reading as the "gold standard" for judging validity of the treating physicians' and official radiologists' readings, sensitivity (.677 vs .647), specificity (.828 vs .849), positive predictive value (PPV, .537 vs .571), and kappa index (kappa, .462 vs .475) were quite similar. By contrast, agreement by the treating physicians was considerably higher with the official radiologists' readings as gold standard: sensitivity = .756, specificity = .922, PPV = .795, and kappa = .688. When the treating physician's reading was positive, the official radiologists' positivity rate was much higher than the blind radiologist's (74.4% vs 51.8%, P less than .005), sensitivity was high (.884) but specificity was low (.436), PPV was .663, and kappa was .326.(ABSTRACT TRUNCATED AT 250 WORDS)

Fever↗
PubMed1991

Very low birth weight: a problematic cohort for epidemiologic studies of very small or immature neonates.

Despite widespread acceptance of the concept of very low birth weight (VLBW), i.e., birth weight of less than or equal to 1,500 g, VLBW infants represent an extremely heterogeneous group of newborns, including those with very immature gestational age and those who are more mature but extremely growth retarded. To demonstrate how use of the VLBW rubric can lead to confounding bias that is not only large in magnitude but impossible to control satisfactorily, the authors divided 640 consecutive live neonates born in the Royal Victoria Hospital, Montreal, Canada, from 1978 to 1987 into two overlapping groups: a VLBW cohort (birth weight, 500-1500 g; n = 573) and a gestational age cohort (gestational age, 23-30 completed weeks; n = 466). Variation in growth status by gestational age was much more uniform in the 23- to 30-week cohort. Thus, although mean birth weight was similar in the 500- to 1,500-g and 23- to 30-week cohorts (1,055 vs. 1,064 g), the 500- to 1,500-g cohort was more mature (mean gestational age, 28.8 vs. 27.8 weeks; upper range, 39.7 vs. 30.9 weeks) and had twice the rate of intrauterine growth retardation (25.7 vs. 11.5%). These differences in maturity and growth resulted in a misleading protective effect of intrauterine growth retardation against in-hospital death in the 500- to 1,500-g cohort (crude odds ratio = 0.55 (95% confidence interval 0.36-0.83] and a greater discrepancy in maturity between cesarean- and vaginally delivered infants (3.1 vs. 1.5 weeks) in the 500- to 1,500-g vs. 23- to 30-week cohorts. These differences arise from inextricable confounding of growth status and maturity in the 500- to 1,500-g cohort, the most mature infants also being the most growth retarded. The removal of well-grown infants with birth weights of greater than 1,500 g from the VLBW cohort leads to a progressively distorted spectrum of growth with advancing gestational age and an artifactual blunting of the beneficial effects of increasing maturity. The authors suggest that whenever fetal growth is an important exposure, outcome, or confounding variable, epidemiologic studies of extremely small or immature newborns should be based on gestational age rather than the VLBW criterion.

Bias↗