SEARCH · PubMed Health

Results for “systematics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources

PubMed1999

Improved evaluation of the location and mechanism of mitral valve regurgitation with a systematic transesophageal echocardiography examination.

UNLABELLED: Mitral regurgitation (MR) is a major determinant of outcome in cardiac surgery. The location and mechanism of mitral lesions determine the approach to various repairs and their feasibility. Because of incomplete evaluations or change in patient condition, detailed intraoperative transesophageal echocardiography (TEE) examination of the mitral valve may be required. We hypothesized that a systematic TEE mitral valve examination would allow precise identification of the anatomic location and mechanism of MR in patients undergoing mitral surgery. We designed a systematic mitral valve examination consisting of six views: five-chamber, four-chamber, two-chamber anterior, two-chamber mid, two-chamber posterior and short-axis. We used this examination prospectively in 13 patients undergoing mitral valve surgery for severe MR and compared the results with the surgical findings. We then retrospectively interpreted 11 similar patients who had undergone intraoperative TEE studies before this examination. TEE correctly diagnosed the mechanism and precise location of pathology in 12 of 13 patients in the prospective group, but in only 6 of 10 patients in the retrospective group. TEE also correctly identified 75 of 78 mitral segments (96%) as being normal or abnormal. In the retrospective group, only 42 of 60 segments (70%) were correctly identified (P < 0.001). We conclude that this systematic TEE mitral valve examination improves identification of mitral segments and precise localization of pathologies and may also improve the diagnosis of the mechanism of MR. IMPLICATIONS: In this article, we describe how a systematic examination of the mitral valve by using transesophageal echocardiography allows identification of the different segments of the mitral valve, precise localization of pathology, and helps to diagnose the mechanism of mitral regurgitation. This is important in determining an approach to mitral valve repair and its feasibility.

Anesthesia↗

PubMed2004

The value of systematic reviews as research activities in medical education.

Medical residents and postdoctoral fellows are often required to conduct and publish original research as part of their medical education. However, their relative lack of experience, time, money, and sometimes supervision in conducting original research often results in research of modest quality on topics of limited importance. Such research may also consume scarce resources from the sponsoring institution. Manuscripts describing such research are often unremarkable, although most are submitted for publication, where editors and peer reviewers will spend time evaluating them. Systematic reviews of the literature, however, offer similar training in the scientific method, are relatively inexpensive to conduct, teach critical appraisal of the literature, give trainees a thorough command of the topic studied, and provide even new investigators the opportunity to make important contributions to the literature. Systematic reviews of the literature should thus be acceptable alternatives to original research assignments for most trainees in medical education programs. The author reviews the characteristics of systematic reviews, outlines the steps in conducting them, identifies the lessons learned from completing each step, and compares the advantages and disadvantages of systematic reviews with those of conducting original research.

Biomedical Research↗

PubMed1981

Systematic method of development in liquid chromatography applied to the determination of antiepileptic drugs.

The object of a liquid-chromatographic analysis is to separate, identify, and quantitate the constituents of interest in a sample mixture within an acceptable analysis time. This will be achieved by a systematic analysis development rather than by a trial-and-error approach. Such a systematic procedure requires a knowledge of the chromatographic parameters governing resolution and analysis time and their relative influences on resolution and its experimental implication. Furthermore, basic information about the mechanisms of the modes of liquid chromatography (adsorption, partition, ion exchange, and steric exclusion) and about the types of sample which can be preferentially analyzed by them is necessary. This information leads to a rational selection of the separation system that promises the best chance of success. In the subsequent experimental work, the analyst systematically measures and calculates resolution and analysis time as functions of selectivity, capacity, and efficiency of the phase system under selected chromatographic conditions. The essential chromatograms, tables, and graphs resulting from this systematic method of development are documented so that it is possible to replicate the analysis procedure in the laboratories involved. The result is a set of chromatographic conditions capable of achieving an optimum compromise between resolution and analysis time. The procedure is applied to routine therapeutic drug monitoring of antiepileptic drugs in patient serum.

Anticonvulsants↗

PubMed2003

A nomogram to predict seminal vesicle invasion by the extent and location of cancer in systematic biopsy results.

PURPOSE: We determined whether systematic biopsy results increases the accuracy of standard clinical information in predicting seminal vesicle invasion (SVI). MATERIALS AND METHODS: We analyzed a retrospective cohort of 763 patients with clinical stages T1c-T3 prostate cancer who were diagnosed by systematic biopsy and treated with radical prostatectomy. We recorded the location of each biopsy core and measured the length of cancer and total length of each core. Using logistic regression analysis we constructed and internally validated a nomogram to predict SVI. RESULTS: A total of 60 patients (7.9%) had SVI. Cancer was present in a biopsy core from the base in 437 patients, of whom 12.8% had SVI compared with only 1.2% of the 326 without cancer at the base. None of the 275 patients with prostate specific antigen (PSA) 10 ng/ml or less and no cancer at the base had SVI. On multivariate analysis serum PSA (p <0.0005), primary Gleason grade (p = 0.028) and percent cancer at the base (p <0.005) were the only significant predictors of SVI. The predictive accuracy of a standard model that included only stage, grade and PSA was maximally enhanced by including the percent cancer at the base (p = 0.0013). A nomogram that incorporated this variable produced probabilities of SVI that differed from the standard model by +/- 10% in 68% of the cases. CONCLUSIONS: The presence and amount of cancer in systematic needle biopsy cores from the base of the prostate strongly predicts the presence of SVI. Systematic biopsy results enhance the accuracy of nomograms to predict SVI.

Adult↗

PubMed1997

Application of energy-resolved measurements to Laue diffraction: determination of unit-cell parameters, deconvolution of harmonics and assignment of systematic absences.

The use of energy-resolved area detection of Laue diffraction patterns for the determination of unit-cell parameters and systematic absences is demonstrated. Seven different crystals having previously known unit cells were re-examined using Laue diffraction methods. These crystals included four different crystal systems including cubic, orthorhombic, tetragonal and monoclinic cells. The crystals had cell sizes ranging from 179.4 to 4588.3 A(3). Comparison of known and re-determined cells showed good agreement (ratio of known to measured cells = 0.987 +/- 0.18). A single procedure was suitable for all unit-cell determinations. The accuracy of the method is presently limited by the quality of the available energy measurements. Some of the crystals represent space groups containing systematic absences normally obscured by harmonic overlap when using the Laue method. These include absences due to 2(1) screw axes (h, k or 1 = 2n + 1) and cell centering (h + k = 2n + 1). All systematic absences were identified using a combination of multiple linear regression with either stepwise elimination or stepwise inclusion and an F test for assignment of systematic absence. The methods are discussed in detail and simulations are used to evaluate critical tolerances for future systems.

Journal Article↗

PubMed2007

Systematic reviews of bladder training and voiding programmes in adults: a synopsis of findings on theory and methods using metastudy techniques.

AIM: This paper reports a comparison of four Cochrane systematic reviews on bladder training and voiding programmes for the management of urinary incontinence using metastudy descriptive techniques. It presents a synopsis of findings on theory and methods for interventions. BACKGROUND: From the mid-1970s bladder training, prompted voiding, habit retraining and timed voiding have been developed and form the basis of nursing practice for the management of urinary incontinence in adults in institutional and community settings. METHODS: A synopsis of four Cochrane systematic reviews was undertaken using metastudy techniques developed for qualitative research and has provided a discursive comparison and contrast of the selection and appraisal of primary research, meta-theory and meta-method. FINDINGS: All programmes share a therapeutic focus on voiding and the degree and active participation of the client and caregiver. Bladder training focuses on the restoration of continence, while prompted voiding, habit retraining and timed voiding focus on the avoidance of incontinence. Bladder training and prompted voiding share the two characteristics of cognitive behavioural modification and active client participation. Habit retraining and timed voiding pre-empt episodes and avoid incontinence using operant conditioning rather than modifying behaviour. Variability of methods and operational terminology makes comparison between studies difficult. Use of cognitive behavioural approaches and operant conditioning need to be better understood in relation to future theory, interventions and study design. Bladder training is aimed at people who are cognitively and physically able, while the other voiding programmes are mainly used with for people with cognitive and physical impairments reliant on caregivers. CONCLUSION: The theoretical approaches underpinning bladder training and voiding programmes, their components and suitability for patients need to be re-considered when designing future studies. There is a need for long-term follow-up in future studies. Future trials should adhere to recognized standards of good practice and incorporate outcomes from existing systematic reviews to enable future meta-analysis to be undertaken. Metastudy techniques for the synthesis of qualitative research provide useful methods for the descriptive synopsis of quantitative systematic reviews.

Adult↗

PubMed2006

Prediction of the variance of stereological volume estimates from systematic sections using computer-intensive methods.

The Cavalieri method is an unbiased estimator of the total volume of a body from its transectional areas on systematic sections. The coefficient of error (CE) of the Cavalieri estimator was predicted by a computer-intensive method. The method is based on polynomial regression of area values on section number and simulation of systematic sectioning. The measurement function is modelled as a quadratic polynomial, with an error term superimposed. The relative influence of the trend and the error component is estimated by techniques of analysis of variance. This predictor was compared with two established short-cut estimators of the CE based on transitive theory. First, all predictors were applied to data sets from six deterministic models with analytically known CE. For these models, the CE was best predicted by the older short-cut estimator and by the computer-intensive approach, if the measurement function had finite jumps. The best prediction was provided by the newer short-cut estimator when the measurement function was continuous. The predictors were also applied to published empirical datasets. The first data set consisted of 10 series of areas of systematically sectioned rat hearts with 10-13 items, the second data set consisted of 13 series of systematically sampled transectional areas of various biological structures with 38-90 items. On the whole, similar mean values for the predicted CE were obtained with the older short-cut estimator and the computer-intensive method. These ranged in the same order of magnitude as resampling estimates of the CE from the empirical data sets, which were used as a cross-check. The mean values according to the newer short-cut CE estimator ranged distinctly lower than the resampling estimates. However, for individual data sets, it happened that the closest prediction as compared to the cross-check value could be provided by any of the three methods. This finding is discussed in terms of the statistical variability of the resampling estimate itself.

Analysis of Variance↗

PubMed2006

On hidden heterogeneity in directional asymmetry--can systematic bias be avoided?

Directional asymmetry (DA) biases the analysis of fluctuating asymmetry (FA) mainly because among-individual differences in the predisposition for DA are difficult to detect. However, we argue that systematic bias mainly results from predictable associations between signed right-left asymmetry and other factors, i.e. from systematic variation in DA. We here demonstrate methods to test and correct for this, by analysing bilateral asymmetry in size and shape of an irregular sea urchin. Notably, in this model system, DA depended significantly on body length and geographic origin, although mean signed asymmetry (mean DA) was not significant in the sample as a whole. In contrast to the systematic variation in DA, undetectable, random variability in the underlying DA mainly leads to reduced statistical power. Using computer simulations, we show that this loss of power is probably slight in most circumstances. We recommend future studies on FA to routinely test and correct for not only as yet for mean DA, but also for systematic variation in DA.

Analysis of Variance↗

PubMed1995

Usefulness of digital rectal examination, serum prostate-specific antigen, transrectal ultrasonography and systematic prostate biopsy for the detection of organ-confined prostate cancer.

The detection rate of organ-confined prostate cancer by digital rectal examination (DRE), serum prostate-specific antigen (PSA), and transrectal ultrasound (TRUS) of the prostate, as well as the value of a directed, guided transrectal core biopsy for the prostate (TRUS-guided biopsy) combined with systematic biopsy, were evaluated. The subjects were 171 patients with urinary symptoms suggestive of prostatic disease excluding those with clinical stage C and D prostate cancer. Twenty-five patients (14.6%) had prostate cancer, 127 (74.2%) had benign prostate hypertrophy, four (2.3%) had prostatic intraepithelial neoplasia, eleven (6.4%) had inflammation, and four (2.3%) had normal prostate tissue. The incidence of detection of hypoechoic findings by TRUS in the patients in whom nodules were detected by DRE or who had elevated serum PSA was higher than that in patients with negative diagnostic findings. In 22 of the 25 patients with prostate cancer, the cancer was detected by recognition of a hypoechoic area on TRUS. In 10 of these 22 patients, prostate cancer was also detected by systematic biopsy in isoechoic areas. Prostate cancer was detected by systematic biopsy in three patients without hypoechoic findings. The positive predictive value for patients with abnormal findings on all three tests was 64.3%, which is significantly higher than that for patients with any other combination of findings (p < 0.05). Our results indicate that the combination of DRE, serum PSA and TRUS is useful for the detection of organ-confined prostate cancer, and that TRUS and TRUS-guided prostate biopsy combined with systematic biopsy should be performed in patients with abnormal findings for both DRE and PSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed2004

Transrectal ultrasound-guided transperineal 14-core systematic biopsy detects apico-anterior cancer foci of T1c prostate cancer.

AIM: The optimal biopsy strategy for prostate cancer detection, especially in men with isolated prostate-specific antigen (PSA) elevation, remains to be defined. We evaluated diagnostic yield and safety of transrectal ultrasound (TRUS)-guided transperineal systematic 14-core biopsy and compared the spatial distribution of cancer foci detected with this technique in men with and without abnormality on digital rectal examination (DRE). METHODS: In a prospective study, 289 men aged between 50 and 87 years (median age, 70 years) underwent TRUS-guided transperineal systematic 14-core prostate biopsy because of elevated PSA and/or abnormal DRE findings. Using the fan technique, 12 cores from the peripheral zone and two cores from the transition zone were obtained systematically. To characterize the spatial distribution of cancer positive cores, site-specific overall and unique cancer detection rates were compared between stage T1c and T2 cancers. RESULTS: Prostate cancer was detected in 105 of the 289 patients (36%). Major complications requiring prolonged hospital stay or re-hospitalization during a 4-week postbiopsy period were rare (1.4%). Sixty-seven stage T1c cancers were identified. These cancers were associated with significantly lower PSA and a smaller number of cancer positive cores when compared with stage T2 cancers (n= 38). The overall cancer detection rate was highest at the anterior peripheral zone and the posterior peripheral zone in stage T1c and stage T2 cancers, respectively. The unique cancer detection rate at the anterior peripheral zone was significantly higher in stage T1c cancers than in stage T2 cancers. Therefore, when the prostate is extensively biopsied using the transperineal approach, cancer positive cores are characteristically distributed anteriorly in stage T1c cancers and posteriorly in stage T2 cancers. CONCLUSIONS: TRUS-guided transperineal systematic 14-core biopsy showed an apico-anterior distribution of cancer foci in stage T1c prostate cancers.

Aged↗

PubMed2004

Significance of cancer detection in the anterior lateral horn on systematic prostate biopsy: the effect on pathological findings of radical prostatectomy specimens.

OBJECTIVE: To clarify the significance of cancer detection in the anterior lateral horn (ALH) on systematic prostate biopsy in relation to its effect on the pathological findings from retropubic radical prostatectomy (RRP) specimens. PATIENTS AND METHODS: The study included 84 consecutive patients who underwent RRP at our institution between January 1999 and December 2002, after being diagnosed as having prostate cancer, based on systematic prostate biopsies that included the areas taken by standard sextant biopsies and the bilateral ALHs. Several clinicopathological factors of these patients were analysed in relation to the presence or absence of cancer in the ALH on systematic biopsy. RESULTS: Of the 84 patients, cancer was detected in the ALH in 44 (group A), but not in the remaining 40 (group B). There were no significant differences in age, preoperative serum prostate-specific antigen level, or prostate volume between the groups. However, the incidence of bilateral positive cores and the percentage of positive biopsy cores in group A were significantly higher than those in group B. Pathological examinations of RRP specimens showed no significant differences in the incidence of lymphatic invasion, vascular invasion and perineural invasion, or Gleason score between the groups, but group A had a significantly larger tumour volume and higher incidence of extraprostatic disease than group B. CONCLUSIONS: Despite similar biological tumour characteristics and irrespective of the cancer location in the ALH, advanced and extensive disease frequently involves the ALH. Therefore, more aggressive treatment should be considered if cancer is detected in the ALH by systematic prostate biopsy.

Aged↗

PubMed2005

Sources of evidence for systematic reviews of interventions in diabetes.

AIMS: To analyse the effect on systematic reviews in diabetes interventions of including only trials that are indexed in medline, and to assess the impact of adding trials from other databases and the grey literature. METHODS: All systematic reviews of diabetes interventions which included a meta-analysis of randomized controlled trials, and were published since 1996, were selected. The impact on the meta-analysis of including only those trials indexed in medline, and the effect of then adding trials from other sources, was assessed. Where possible this was measured quantitatively, by redoing the meta-analysis, otherwise a qualitative estimate was made. RESULTS: Forty-four systematic reviews met our inclusion criteria. There were 120 articles reporting trial data which were not indexed in medline. These came from 52% of the reviews. In 34% of the reviews, basing a meta-analysis on a search of only medline would miss trials that could affect the result. Sources of non-medline data which had the biggest effect on the meta-analyses were journal articles from central and embase (mainly in Diabetes, Nutrition and Metabolism) and unpublished data (mainly from industry). The exceptions were journal articles on herbal medicine, mostly indexed in Chinese language databases. CONCLUSIONS: A search of only the medline database is insufficient for systematic reviews of diabetes, because in about 34% of reviews the missed trials could affect the results of the meta-analysis. It is recommended that central (on the Cochrane Library) also be searched. Scanning meeting abstracts, and seeking unpublished data are also recommended if the intervention has only recently been introduced.

Databases, Bibliographic↗

PubMed2005

Accounting for both random errors and systematic errors in uncertainty propagation analysis of computer models involving experimental measurements with Monte Carlo methods.

A Monte Carlo method is presented to study the effect of systematic and random errors on computer models mainly dealing with experimental data. It is a common assumption in this type of models (linear and nonlinear regression, and nonregression computer models) involving experimental measurements that the error sources are mainly random and independent with no constant background errors (systematic errors). However, from comparisons of different experimental data sources evidence is often found of significant bias or calibration errors. The uncertainty analysis approach presented in this work is based on the analysis of cumulative probability distributions for output variables of the models involved taking into account the effect of both types of errors. The probability distributions are obtained by performing Monte Carlo simulation coupled with appropriate definitions for the random and systematic errors. The main objectives are to detect the error source with stochastic dominance on the uncertainty propagation and the combined effect on output variables of the models. The results from the case studies analyzed show that the approach is able to distinguish which error type has a more significant effect on the performance of the model. Also, it was found that systematic or calibration errors, if present, cannot be neglected in uncertainty analysis of models dependent on experimental measurements such as chemical and physical properties. The approach can be used to facilitate decision making in fields related to safety factors selection, modeling, experimental data measurement, and experimental design.

Journal Article↗

PubMed1999

Systematic reviews: a logical methodological extension of evidence-based medicine.

Academic Emergency Medicine is interested in publishing systematic reviews (also known as meta-analyses) containing explicit, quantitative compilations of valid, critically appraised evidence targeted at topics relevant to the science and practice of emergency medicine. This article presents a strategy for the performance and reporting of systematic reviews, based on established recommendations. A well-performed systematic review of the literature may provide clinically relevant information otherwise unobtainable, and has potential to alter patient care. Systematic reviews are logical methodological extensions of evidence-based medicine.

Data Collection↗

PubMed2001

In search of truth: the role of systematic reviews and meta-analyses for assessing the effectiveness of rehabilitation with oral implants.

BACKGROUND: It is difficult to determine the effectiveness or potential harm of dental therapies. Thus, any tools able to condense reliable scientific information would be of benefit. PURPOSE: To discuss methods for the assessment of the scientific literature and, in particular, of systematic reviews for evaluating the effectiveness of oral implant rehabilitation procedures. MATERIALS AND METHODS: Various study designs and methods to identify scientific evidence are described, discussed, and ranked. Issues on how to critically appraise randomized controlled clinical trials (RCTs) and systematic reviews are presented. RESULTS: Properly conducted RCTs and structured critical systematic reviews are the gold standard of clinical research for assessing whether a therapeutic intervention is effective. In the field of oral implantology, there is an urgent need to implement more RCTs and to summarize their results in systematic reviews. CONCLUSIONS: Searching of the truth requires training and critical skill. Dentists should be trained on how to integrate their clinical experience with evidence-based research and on how to discriminate between clinically useful scientific information and less useful research.

Animals↗

PubMed2004

Efficacy of educational interventions targeting primary care providers' practice behaviors: an overview of published systematic reviews.

OBJECTIVES: Primary care providers (e.g., family physicians, pediatricians, registered nurses, physician assistants, and nurse practitioners) could play a pivotal role in the provision of preventive services, especially for very young children (younger than 3 years old) and population groups with limited access to dental care. Given the current problems with access to dental care among low-income Americans, we contend there is a need to involve nondental primary health care providers in screening for and preventing oral health problems. The objective of this overview is to present findings from systematic reviews on the efficacy of continuing medical education, printed educational material, academic outreach, reminders, and local opinion leaders on the adoption of new knowledge and practices by primary care providers. METHODS: A search was conducted using the Cochrane Library and MEDLINE. The search aimed to locate systematic reviews published between January 1988 and March 2003. Two researchers independently extracted data and assessed study quality using a modified version of the QUOROM statement. RESULTS: Eleven systematic reviews were included in this overview. The evidence from the included systematic reviews showed that formal continuing medical education (CME) and distributing educational materials did not effectively change primary care providers' behaviors. There are effective interventions available to increase knowledge and change behaviors of primary care providers, such as small group discussion, interactive workshops, educational outreach visits, and reminders. CONCLUSION: There is a limited knowledge base on the efficacy of the selected interventions on oral health screening by primary care providers. Considering the potential role of primary care providers in improving oral health of underserved populations, this research area should receive more attention.

Attitude of Health Personnel↗

PubMedDate not supplied

Development of a systematic oral care program for frail elderly persons.

The purpose of this study was to develop, implement and evaluate a systematic oral care program for community-dwelling-dependent or institutionalized elderly adults. The study group consisted of 20 dependent elderly adults of which 15 were living in the community and five were in a nursing home. After eight weeks of systematic oral care, the plaque and gingival indices were scored and compared with baseline measurements. Also at the end of the study, caregivers completed a questionnaire that assessed their perspective on the advantages, disadvantages, burden and fatigue in providing the systematic oral care program. The results of this study demonstrate that a systematic oral care program reduced plaque and gingival indices for the subjects as well as reducing the caregivers' burden and fatigue in providing daily oral care.

Aged↗

PubMed2005

Understanding systematic reviews and meta-analysis.

This review covers the basic principles of systematic reviews and meta-analyses. The problems associated with traditional narrative reviews are discussed, as is the role of systematic reviews in limiting bias associated with the assembly, critical appraisal, and synthesis of studies addressing specific clinical questions. Important issues that need to be considered when appraising a systematic review or meta-analysis are outlined, and some of the terms used in the reporting of systematic reviews and meta-analyses--such as odds ratio, relative risk, confidence interval, and the forest plot--are introduced.

Child↗