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PubMed2000

Rapid versus slow rate of advancement of feedings for promoting growth and preventing necrotizing enterocolitis in parenterally fed low-birth-weight infants.

BACKGROUND: Very premature infants fed by gavage are unable to regulate their own enteral intake. Therefore the rate at which feedings are advanced must be determined by caregivers. While advancing feedings too rapidly may increase the risk of necrotizing enterocolitis, advancing feedings too slowly might result in undernutrition or prolonged hospital stay. OBJECTIVES: For low-birth-weight premature infants receiving parenteral fluids, to assess the effect of different rates of advancement of enteral feedings beginning at the same age on measures of feeding tolerance and neonatal outcome. SEARCH STRATEGY: Search strategies included a Medline search and a search of the Oxford Database of Perinatal Trials; additional references were sought in review articles, relevant chapters of textbooks, a previous systematic review, recent American Pediatric Society - Society for Pediatric Research abstracts, personal files, and personal communication. SELECTION CRITERIA: Only randomized or quasi-randomized trials were considered. Trials were included if premature low-birth-weight infants were studied and if the strategies being compared were different rates of advancement of feedings (accomplished by either differences in volume or concentration) with the onset of feedings at the same postnatal age in each group. DATA COLLECTION AND ANALYSIS: The two reviewers reached consensus for inclusion of trials. Data regarding clinical outcomes were extracted and evaluated by the two reviewers independently of each other. Authors were contacted as needed and feasible to clarify or provide missing data. The specific data that were needed were requested in writing. MAIN RESULTS: Among infants randomized to more rapid rates of advancement of feedings, there was an overall reduction in days to full enteral feeding and days to regain birth weight. There was no effect on necrotizing enterocolitis (relative risk = 0.90, 95% confidence interval = 0. 46-1.77). REVIEWER'S CONCLUSIONS: There are suggested advantages of more rapid rates of advancing feedings in premature low-birth-weight infants (shorter time to regain birth weight and shorter time to achieve full feedings). It is unclear whether this strategy should be adopted as routine practice because of limited information regarding safety (broad confidence intervals for the incidence of necrotizing enterocolitis) and the effect on length of hospital stay (broad confidence intervals). Because different birth weight ranges and different rates of advancement were used in each of these studies, the ideal rate of advancement remains unclear, particularly for extremely-low-birth-weight infants.

Enteral Nutrition↗

PubMedDate not supplied

Theory and practice in medical statistics.

The discipline of statistics generally, and that of medical statistics in particular, has evolved through two traditions, the theoretical and the practical. Their history, traced briefly here, shows recurrent points of contact and a process of gradual merging which is now almost complete. However, the current tendency to build complex mathematical and computing models may lead to over-confidence in their conclusions, when some crucial aspects of the data cannot easily be modelled satisfactorily. Illustrations are drawn from the use of formal stopping rules in the monitoring of clinical trials, and from the treatment of missing data and incomplete compliance with the trial protocol.

Clinical Trials as Topic↗

PubMed1980

Reliability of the CES-D Scale in different ethnic contexts.

Reliability of the Center for Epidemiologic Studies Depression Scale, a 20-item symptom checklist, is examined using data from a sample of community respondents containing Anglos (254), Blacks (270), and Mexican Americans (181). Although the survey response rate was lower for Mexican Americans, quality of the data provided by this group was not significantly different from that for Anglos or Blacks. That is, there were no differences among these groups in terms of missing data or internal consistency reliabilty (as measured by Cronbach's alpha and Spearman-Brown split halves). Factor-analytic results also demonstrate the same general structure of responses among the three groups.

Black or African American↗

PubMed2000

Comparison of 3-D maximum a posteriori and filtered backprojection algorithms for high-resolution animal imaging with microPET.

We have evaluated the performance of two three-dimensional (3-D) reconstruction algorithms with data acquired from microPET, a high resolution tomograph dedicated to small animal imaging. The first was a linear filtered-backprojection algorithm (FBP) with reprojection of the missing data, and the second was a statistical maximum a posteriori probability algorithm (MAP). The two algorithms were evaluated in terms of their resolution performance, both in phantoms and in vivo. Sixty independent realizations of a phantom simulating the brain of a baby monkey were acquired, each containing three million counts. Each of these realizations was reconstructed independently with both algorithms. The ensemble of the 60 reconstructed realizations was used to estimate the standard deviation as a measure of the noise for each reconstruction algorithm. More detail was recovered in the MAP reconstruction without an increase in noise relative to FBP. Studies in a simple cylindrical compartment phantom demonstrated improved recovery of known activity ratios with MAP. Finally, in vivo studies also demonstrated a clear improvement in spatial resolution using the MAP algorithm. The quantitative accuracy of the MAP reconstruction was also evaluated by comparison with autoradiography and direct well counting of tissue samples and was shown to be superior.

Algorithms↗

PubMedDate not supplied

Methodological considerations with secondary analyses.

The use of secondary data sets has begun to receive increased attention in nursing research. Shrinking grant dollars, continuing pressure to produce replicable generalizable research results, and a growing interest in outcomes management and research have all contributed to an interest in examining how data may be used for multiple purposes. Secondary data analysis may offer the practitioner and researcher ready access to large data sets with multiple variables; yet, there are potentially significant methodological concerns that should be well understood and managed in the initial query design. Considered here will be some of the issues regarding the reliability and validity of large data sets used for secondary analysis, including a discussion on maintaining the integrity of those files as they are moved, merged, and transformed. Finally, methods for managing missing data are reviewed.

Abstracting and Indexing↗

PubMed2000

Input respiratory impedance measured by head generator in preschool children.

The upper airway wall motion represents a serious problem when measuring the input impedance of the respiratory system (Zrs) by the forced oscillation technique, particularly in young children. To minimize this error, it has been proposed to vary transrespiratory pressure around the head rather than directly at the mouth, using the head generator technique (HGT). The aim of this study was to collect normative data in preschool children in whom the technique may prove most useful. Zrs was measured using HGT and 4-32-Hz pseudorandom noise input in 127 healthy children. Age ranged from 2. 8 to 7.4 years and height (H) from 0.89 to 1.29 m. The fast Fourier transforms of pressure and flow allowed us to calculate respiratory system resistance (Rrs(f)) and reactance (Xrs(f)) at each frequency (f). Resonant frequency (fn), respiratory system inertance (Irs), and compliance (Crs) were derived from the Xrs(f) data. The technique was accepted by more than 95% of the children. A coherence function </=0.95 required us to reject Zrs values in the lower frequency spectrum. These missing data did not allow reliable estimation of fn, Irs, and Crs in 44% of children. Regression equations of Zrs on growth parameters were obtained. H was the only significant predictive variable. The decrease of Rrs with growth was best described by a multiplicative model [e.g., ln (Rrs(20)) = 2. 5301 - 2.3837. ln (H)]. The slope of the regression lines of Xrs on H was dependent on f: positive between 4 and 16 Hz, negative at high frequency (e.g., 32 Hz), and nonsignificant in the intermediate range (e.g., 20 Hz). Irs and fn decreased significantly and Crs increased as H increased. The current study provides reference values for input impedance of the respiratory system in preschool children with upper airway artifacts minimized. HGT should be particularly helpful at or around 20 Hz, where the signal to noise ratio is larger than at lower frequencies but where upper airway artifacts may significantly corrupt measurements with the standard generator.

Airway Resistance↗

PubMed2001

Bisphosphonates for osteoporosis in people with cystic fibrosis.

BACKGROUND: Osteoporosis is a disorder of bone mineralization that can lead to reduced bone mineral density and an increased risk for fractures. It is found in about one third of adults with cystic fibrosis. Bisphosphonates have been shown to increase bone mineral density and decrease the risk of new fractures in post-menopausal women and in patients receiving long-term oral corticosteroids. OBJECTIVES: To assess the effects of bisphosphonates on the frequency of fractures, bone mineral density, quality of life, adverse events, study withdrawals, and survival in people with cystic fibrosis. SEARCH STRATEGY: Relevant trials were identified in the Cochrane Cystic Fibrosis and Genetic Disorders Review Group specialised register of controlled trials by the centre co-ordinator. This register comprises references identified from comprehensive electronic database searches, handsearching of relevant journals and of conference proceedings. Additional sources such as abstract books for osteoporosis conferences were hand-searched by the authors. The most recent search(es) were conducted in February 2001. SELECTION CRITERIA: Randomised controlled trials of at least six months duration that studied the use of bisphosphonates in adults with cystic fibrosis were considered for inclusion. Outcomes included one of the following: fractures, bone mineral density, quality of life, adverse events, study withdrawals, or survival. DATA COLLECTION AND ANALYSIS: Information on study design, participants, interventions, and outcomes was abstracted from included studies. Two independent reviewers abstracted the information. Authors were contacted to obtain missing data. MAIN RESULTS: Two trials were identified in the trials search. Both trials with a total of 65 participants were included in this review. One study examined patients without lung transplants while the other study included only patients who had received a lung transplant. The intervention in both trials was pamidronate administered intravenously every three months. In patients who had not received a lung transplant, bone mineral density at axial sites was increased after six months of treatment in the treatment group compared to the control group (lumbar spine WMD [for % change BMD] = 5.8 [95% CI 4.63 to 6.97], hip WMD = 3.00 [95% CI 1.99 to 4.01]). There was a small decrease in forearm bone mineral density in patients treated with pamidronate versus controls (distal forearm WMD = -1.70 [95% CI -2.46 to -0.94]). Bone pain was the most common adverse event occurring in 11/15 participants not using corticosteroids (RR = 24.40, 95% CI 1.57 to 381.48). There was no difference in survival (RR = 1.00, 95% CI 0.83 to 1.20), although this may be due to short follow-up and small sample size. In patients who had received a lung transplant, the number of new fractures did not change with the use of pamidronate (non-vertebral RR = 3.38 [95% CI 0.39 to 29.29], vertebral RR = 0.56 [95% CI 0.17 to 1.89]). Bone mineral density at axial sites was increased after two years of treatment in the treatment group compared to the control group (lumbar spine WMD [for % change in BMD] = 6.20 [95% CI 4.28 to 8.12], femur WMD = 7.90 [95% CI 5.78 to 10.03]). REVIEWER'S CONCLUSIONS: Intravenous pamidronate increases bone mineral density at axial sites in people with cystic fibrosis, although it can cause severe bone pain in patients not receiving corticosteroids. Additional studies in larger populations are needed to determine the effect on fracture rate and survival.

Bone Density↗

PubMed2004

Validity and reliability of a questionnaire to measure the impact of lower urinary tract symptoms on quality of life: the Leicester Impact Scale.

AIMS: To develop a condition specific quality of life measure for males and females with urinary storage symptoms of urgency, frequency, nocturia and incontinence. MATERIALS AND METHODS: A sample of community dwelling males and females aged 40 years or more who were taking part in an epidemiological study provided data for development and validation of the scale. Questions were developed from literature review and discussions with clinicians and patients. Inclusion of items was dependent on levels of missing data and principal components analysis. Validity was assessed by comparison with the Hospital Anxiety and Depression Scale, the Bradburn Negative Affect Scale and single questions concerning the problematic nature of symptoms. Construct validity was assessed by comparing cases and non-cases, and patients with different symptom patterns. Test-retest and inter-rater reliability statistics were calculated for individual items. Responsiveness to change was measured in subjects taking part in a randomised controlled trial of a nursing intervention. RESULTS: The scale showed high levels of internal consistency and measures of construct validity were as hypothesised. Test-retest and inter-rater reliability was moderate to excellent. The distribution of scores was skewed with low levels of impact but the questionnaire was responsive to conservative treatments in patients receiving a nursing intervention. CONCLUSIONS: The questionnaire proved to be a valid and reliable interviewer administered instrument for measuring impact of urinary symptoms.

Aged↗

PubMed2006

Differential expression of HER-2/NEU receptor of invasive mammary carcinoma between Caucasian and African American patients in the Detroit metropolitan area. Correlation with overall survival and other prognostic factors.

GOALS: HER-2/neu overexpression in invasive mammary carcinoma is associated with more aggressive biologic behavior. Breast cancer in African American (AA) women has been associated with a shorter survival rate than that seen in Caucasians (C). This study evaluated the frequency of HER-2/neu overexpression in C compared to AA patients and the association of HER-2/neu expression with overall survival and other prognostic factors. METHODS: A retrospective review of the SEER data of Karmanos Cancer Institute for patients with invasive mammary carcinoma was conducted between 1998 and 2001. Pathology reports and pathology slides were obtained for those patients with missing data. Available data and material on 608 patients were found. The median follow-up interval was 35 months with a range of 1-91 months. 46.7% of the study population was C while 53.3% was AA. The differential of HER-2/neu expression in C and AA was evaluated. The association of HER-2/neu expression and other prognostic factors with overall survival was carried out by univariate and multivariable analyses using Cox's proportional hazards regression model. PRINCIPLE RESULTS: No statistically significant difference was found in HER-2/neu expression between C and AA patients. Overexpression of HER-2/neu did not correlate with decreased overall survival in this analysis. MAJOR CONCLUSIONS: Breast cancer HER-2/neu expression in AA patients is not statistically different from that of Caucasians. HER-2/neu expression is not associated with overall survival. Among the other prognostic factors analyzed, ER status and histologic grade were not statistically significant.

Adult↗

PubMed1996

A general procedure for the estimation of interdependence.

Dependencies among observations are of interest to psychologists for both methodological and substantive reasons. A general procedure is developed that can be used to estimated dependencies among observations, given a set of a priori expectations about the structure of those dependencies. The utility of this general procedure is illustrated for specific cases: the estimation of serial dependency in time-series data, of dyadic and group interdependence in social psychology, and of reliability. The utility of the approach derives from its generality and from its ability to handle randomly missing data.

Humans↗

PubMed2004

Haplotype block partitioning and tag SNP selection using genotype data and their applications to association studies.

Recent studies have revealed that linkage disequilibrium (LD) patterns vary across the human genome with some regions of high LD interspersed by regions of low LD. A small fraction of SNPs (tag SNPs) is sufficient to capture most of the haplotype structure of the human genome. In this paper, we develop a method to partition haplotypes into blocks and to identify tag SNPs based on genotype data by combining a dynamic programming algorithm for haplotype block partitioning and tag SNP selection based on haplotype data with a variation of the expectation maximization (EM) algorithm for haplotype inference. We assess the effects of using either haplotype or genotype data in haplotype block identification and tag SNP selection as a function of several factors, including sample size, density or number of SNPs studied, allele frequencies, fraction of missing data, and genotyping error rate, using extensive simulations. We find that a modest number of haplotype or genotype samples will result in consistent block partitions and tag SNP selection. The power of association studies based on tag SNPs using genotype data is similar to that using haplotype data.

Algorithms↗

PubMed1976

Data attrition in follow-up studies of alcoholics.

Alcoholics who responded to posttreatment follow-up evaluation showed more improvement than those wh did not respond. Thus nonresponders may bias follow-up research tht does not account for missing data. Several procedures are outlined to increase follow-up return.

Adult↗

PubMed2002

Defining the relationship between plasma glucose and HbA(1c): analysis of glucose profiles and HbA(1c) in the Diabetes Control and Complications Trial.

OBJECTIVE: To define the relationship between HbA(1c) and plasma glucose (PG) levels in patients with type 1 diabetes using data from the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: The DCCT was a multicenter, randomized clinical trial designed to compare intensive and conventional therapies and their relative effects on the development and progression of diabetic complications in patients with type 1 diabetes. Quarterly HbA(1c) and corresponding seven-point capillary blood glucose profiles (premeal, postmeal, and bedtime) obtained in the DCCT were analyzed to define the relationship between HbA(1c) and PG. Only data from complete profiles with corresponding HbA(1c) were used (n = 26,056). Of the 1,441 subjects who participated in the study, 2 were excluded due to missing data. Mean plasma glucose (MPG) was estimated by multiplying capillary blood glucose by 1.11. Linear regression analysis weighted by the number of observations per subject was used to correlate MPG and HbA(1c). RESULTS: Linear regression analysis, using MPG and HbA(1c) summarized by patient (n = 1,439), produced a relationship of MPG (mmol/l) = (1.98 . HbA(1c)) - 4.29 or MPG (mg/dl) = (35.6 . HbA(1c)) - 77.3, r = 0.82). Among individual time points, afternoon and evening PG (postlunch, predinner, postdinner, and bedtime) showed higher correlations with HbA(1c) than the morning time points (prebreakfast, postbreakfast, and prelunch). CONCLUSIONS: We have defined the relationship between HbA(1c) and PG as assessed in the DCCT. Knowing this relationship can help patients with diabetes and their healthcare providers set day-to-day targets for PG to achieve specific HbA(1c) goals.

Blood Glucose↗

PubMed2003

[Planning and implementation of evaluation studies in child and adolescent psychiatry].

An introduction into planning and implementing evaluation studies in child and adolescent psychiatry is presented. After the presentation of theoretical aspects of evaluation studies, the necessity of these studies is elucidated. Further, a conceptualisation of the dimensions of a treatment programme and some criteria for the selection of outcome criteria are offered. In addition to symptomatology, other criteria such as family functioning and quality of life are proposed in this context. Furthermore, it is recommended to ascertain data already at the time of the patient's registration. The influence of drop-out rate on the study result makes it necessary to closely consider any missing data. These and other problems lead to the conclusion that a sophisticated and complex evaluation methodology is required to assess the performance of a child and adolescent treatment programme validly. Finally, the design of the Hamburg evaluation study is presented, which is suitable for the implementation of some of the mentioned aspects.

Adolescent↗

PubMed2004

Avoidance of animal experiments in the new EU Chemicals Regulation - opportunities and problems from the point of view of animal welfare.

On 29 October 2003, the European Commission forwarded the "Proposal for a Regulation of the European Parliament and of the Council concerning the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH), establishing a European Chemicals Agency and amending Directive 1999/45/EC and Regulation (EC) on Persistent Organic Pollutants" to the European Parliament and the Council for adoption under the so-called co-decision procedure. From the point of view of animal welfare it is to be welcomed that it is envisaged better to protect humans and the environment from unknown risks through chemical substances. However, in order to ensure that this goal can be met, extensive amendments to the proposed draft are requested: Instead of continuing to perform animal tests, relevant and reliable non-animal testing strategies should be implemented. Before considering testing, all existing data must be made available, shared and evaluated. This request should be enforced in the new Regulation through an adequate mandatory system. Data requirements must be tailored to the specific substance, to ensure that only such information is collected that is necessary for its safe handling by workers and consumers. Missing data should be determined with non-animal test methods. Finally, the European Union and its Member States are called to provide adequate funding for alternative method research without delay and to call for tenders on those information-gaps that currently prevent the implementation of an entirely non-animal testing strategy, so that such new methods will be available in time for application under the REACH system.

Animal Experimentation↗

PubMed2004

Dietary advice for treatment of type 2 diabetes mellitus in adults.

BACKGROUND: While initial dietary management immediately after formal diagnosis is an 'accepted' cornerstone of treatment of type 2 diabetes mellitus, a formal and systematic overview of its efficacy and method of delivery is not currently available. OBJECTIVES: To assess the effect of type and frequency of different types of dietary advice to all adults with type 2 diabetes on weight, measures of diabetic control, morbidity, total mortality and quality of life. SEARCH STRATEGY: We carried out a comprehensive search of The Cochrane Library (The Cochrane Library Issue 3, 2003), MEDLINE (1966 to October Week 1, 2003), EMBASE (1980 to Week 40, 2003), CINAHL (1982 to October Week 1, 2003), AMED (1985 to October 2003), bibliographies and contacted relevant experts. SELECTION CRITERIA: All randomised controlled trials, of six months or longer, in which dietary advice was the main intervention in adults with type 2 diabetes mellitus. DATA COLLECTION AND ANALYSIS: The lead investigator performed all data extraction and quality scoring with duplication being carried out by one of the other six investigators independently with discrepancies resolved by discussion and consensus. Authors were contacted for missing data. For continuous outcomes, endpoint data were preferred to change data. MAIN RESULTS: Thirty-six articles reporting a total of eighteen trials following 1467 participants were included. Dietary approaches assessed in this review were low-fat/high-carbohydrate diets, high-fat/low-carbohydrate diets, low-calorie (1000 kcal per day) and very-low-calorie (500 kcal per day) diets and modified fat diets. Two trials compared the American Diabetes Association exchange diet with a standard reduced fat diet and five studies assessed low-fat diets versus moderate fat or low-carbohydrate diets. Two studies assessed the effect of a very-low-calorie diet versus a low-calorie diet. Six studies compared dietary advice with dietary advice plus exercise and three other studies assessed dietary advice versus dietary advice plus behavioural approaches. The studies all measured weight and measures of glycaemic control although not all studies reported these in the articles published. Other outcomes which were measured in these studies included mortality, blood pressure, serum cholesterol (including LDL and HDL cholesterol), serum triglycerides, maximal exercise capacity and compliance. The results suggest that adoption of regular exercise is a good way to promote better glycaemic control in type 2 diabetic patients, however all of these studies were at high risk of bias. REVIEWERS' CONCLUSIONS: There are no high quality data on the efficacy of the dietary treatment of type 2 diabetes, however the data available indicate that the adoption of exercise appears to improve glycated haemoglobin at six and twelve months in people with type 2 diabetes. There is an urgent need for well-designed studies which examine a range of interventions, at various points during follow-up, although there is a promising study currently underway.

Adult↗

PubMed2004

Dietary advice for treatment of type 2 diabetes mellitus in adults.

Adult↗

PubMed2003

Genotyping of three candidate genes after whole-genome preamplification of DNA collected from buccal cells.

The amount of genomic DNA obtained from buccal cell methods may be suboptimal for large-scale genetics projects, because the quantity of DNA may be insufficient for the number of analyses proposed. Primer extension preamplification (PEP) methods that can amplify the entire genome 100-fold or more, offer a potential solution to this problem. We compared PEP buccal DNA with genomic buccal DNA from 315 individuals from 97 families of the Colorado Longitudinal Twin Study for three loci: the dopamine transporter, dopamine D4 receptor, and serotonin transporter. A total of 1890 genomic and 1890 PEP alleles were assessed, and 1670 comparisons (88%) agreed after a single determination. Fifty-three individuals had one or more failed initial polymerase chain reactions (PCR), with 81 failed PCRs in total, accounting for 162 missing allele calls. The failed PCRs were repeated once, and 146 of the missing allele calls were recovered. Comparisons between genomic and PEP DNA allele calls showed 37 individuals had one or more discrepancies, for a total of 52 inconsistencies. Of these, the initial PEP result was found to be correct in 18 cases, the initial genomic result was found to be correct in 25 cases, and 9 could not be resolved. Overall, rates of true calls, missing data, and genotyping errors for genomic and PEP DNA samples were nearly identical: of the 1890 genotypes assessed, true calls were found in 1845 genomic and 1840 PEP samples, missing genotypes in 18 genomic and 16 PEP samples, and incorrect assignments in 18 genomic and 25 PEP samples. These results suggest that routine whole-genome preamplification of genomic DNA is an appropriate method for providing DNA to genotype these loci.

Alleles↗