PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “summary statistics”

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 199 records · Page 11Linked to original sources
PubMedDate not supplied

Designing linked micromap plots for states with many counties.

This paper describes the design of linked micromap plots for showing county estimates on a state by state basis. The linked micromap template was specifically developed to represent spatially indexed statistical summaries. Each plot shows regional names, spatial patterns and statistical patterns while linking them all together. Thus the design is useful for communicating summaries from a host of health and environmental studies. The specific design challenge in this paper is to create one-page plots for the states with 60 to 120 counties. While the county names and micromaps take up substantial space, the three examples demonstrate that there is sufficient space to represent two variables. The basic design has the potential for showing more. Consequently the new designs are suitable for presenting sophisticated summaries.

Adolescent↗
PubMed1997

A literature review of low back disorder surveillance measures and risk factors.

OBJECTIVE: The goal of this literature review was to gain insight into low back disorder risk factors via a critical examination of the surveillance measures and analysis techniques employed in existing literature. DESIGN: Fifty-seven original articles were evaluated and categorized as a function of their surveillance measures. BACKGROUND: There have been a plethora of articles concerning the causes of low back disorder, yet no specific risk factors are consistently associated with the development of these disorders. It was hypothesized that different low back surveillance measures and variations in risk factor (dependent variable) measurements have led to the inconsistencies in the literature. METHODS: Five low back disorder surveillance measures and five risk factor categories were defined for this review. Each article was classified on several criteria including: surveillance measures, risk factors, statistical methods, population and type of study. Summary statistics were calculated for the percentage of positive findings as a function of surveillance measure and risk factor category. RESULTS: The most consistently defined surveillance measure was incidence of low back disorder, with 82% of those investigating it as claims from medical records or Occupational Safety and Health Administration records. The combination of surveillance measures and risk factor influenced the outcome of investigations. Ninety-one percent of the direct or video methods of measuring exposure risk factor influenced outcome. Psychosocial measures had positive findings in 70% of the studies examining lost time. Finally, statistical methodology was critical in the outcome of these investigations. CONCLUSIONS: The surveillance measure of incidence had more positive findings, with exposure risk factors and the surveillance measures indicating more advanced stages of low back disorder such as lost time had more positive findings with psychosocial risk factors. Thus, as low back disorders progress to disability, the psychosocial risk factors play a more prominent role. RELEVANCE: In order to prevent low back disorders we must first understand the plethora of epidemiological literature. This literature review provides new insight on the critical issues that have contributed to the results of previous research.

Journal Article↗
PubMed2005

Mesothelioma mortality in Great Britain from 1968 to 2001.

BACKGROUND: The British mesothelioma register contains all deaths from 1968 to 2001 where mesothelioma was mentioned on the death certificate. AIMS: To present summary statistics of the British mesothelioma epidemic including summaries by occupation and geographical area. METHODS: Standardized mortality ratios (SMRs) were calculated for local authorities, unitary authorities and counties. Temporal trends in SMRs were also examined. Proportional mortality ratios (PMRs) were calculated using the Southampton (based on the 1980 standard occupational classification) coding scheme. Temporal trends in PMRs were also examined. RESULTS: The annual number of mesothelioma deaths has increased from 153 in 1968 to 1848 in 2001. Current deaths in males account for about 85% of the cases. The areas of West Dunbartonshire (SMR 637), Barrow-in-Furness (593), Plymouth (396) and Portsmouth (388) have the highest SMRs over the period 1981-2000. The occupations with the highest PMRs are metal plate workers (PMR 503), vehicle body builders (526), plumbers and gas fitters (413) and carpenters (388). CONCLUSIONS: These data reinforce earlier findings that geographical areas and occupations associated with high exposure to asbestos in the past continue to drive the mesothelioma epidemic in Great Britain. However, the trends over time suggest a change in the balance of risk away from traditional asbestos exposure industries to industries where one could describe the exposure as secondary, such as plumbers and gas fitters, carpenters, and electricians.

Adolescent↗
PubMed1999

Feature extraction and quantification of the variability of dynamic performance profiles due to the different sagittal lift characteristics.

Investigation of manual material handling (MMH) tasks, such as lifting, requires the quantification of the various kinematic and kinetic parameters of performance for assessment of the functional capacity and/or task demand profiles. Traditional statistical descriptive analyses usually involve computing the summary statistics (maximum, minimum, mean, and/or range) of the resulting performance parameters over the cycle duration (i.e., lifting/lowering cycle). Consequently, the significant information content of the time-varying signals is diminished, limiting the sensitivity of subsequent hypothesis testing procedures. The present study developed a methodology for representing and quantifying performance data variability of the kinematic and kinetic motion profiles due to the different lift characteristics (load, mode, and speed) during MMH tasks while capturing the temporal characteristics. Using a database of motion profiles from a manual lifting experiment, the Karhunen-Loeve Expansion (KLE) feature extraction technique was shown to be quite effective for representing the various motion profiles. The number of basis vectors (eigenvectors) and corresponding coefficients needed for accurate representation were substantially smaller than the original data set, resulting in data compression. Moreover, the effects of lift characteristics were investigated using analysis of variance techniques that recognize the vectorial constitution of the waveforms. The application of these techniques will enable the quantification of highly phasic profiles and enhance the ability to document the effect of intervening measures such as educational or physical training/exercise on the kinematic and kinetic patterns of performance. Additionally, the differential influence of lift characteristics on the variability of performance during different phases of lifting and lowering provides added resolution in the analysis of MMH tasks.

Adult↗
PubMed1999

Estimation of the average correlation coefficient for stratified bivariate data.

If the relationship between two ordered categorical variables X and Y is influenced by a third categorical variable with K levels, the Cochran-Mantel-Haenszel (CMH) correlation statistic QC is a useful stratum-adjusted summary statistic for testing the null hypothesis of no association between X and Y. Although motivated by and developed for the case of K I x J contingency tables, the correlation statistic QC is also applicable when X and Y are continuous variables. In this paper we derive a corresponding estimator of the average correlation coefficient for K I x J tables. We also study two estimates of the variance of the average correlation coefficient. The first is a restricted variance based on the variances of the observed cell frequencies under the null hypothesis of no association. The second is an unrestricted variance based on an asymptotic variance derived by Brown and Benedetti. The estimator of the average correlation coefficient works well in tables with balanced and unbalanced margins, for equal and unequal stratum-specific sample sizes, when correlation coefficients are constant over strata, and when correlation coefficients vary across strata. When the correlation coefficients are zero, close to zero, or the cell frequencies are small, the confidence intervals based on the restricted variance are preferred. For larger correlations and larger cell frequencies, the unrestricted confidence intervals give superior performance. We also apply the CMH statistic and proposed estimators to continuous non-normal data sampled from bivariate gamma distributions. We compare our methods to statistics for data sampled from normal distributions. The size and power of the CMH and normal theory statistics are comparable. When the stratum-specific sample sizes are small and the distributions are skewed, the proposed estimator is superior to the normal theory estimator. When the correlation coefficient is zero or close to zero, the restricted confidence intervals provide the best performance. None of the confidence intervals studied provides acceptable performances across all correlation coefficients, sample sizes and non-normal distributions.

Aged↗
PubMed2003

An integrated population-averaged approach to the design, analysis and sample size determination of cluster-unit trials.

While the mixed model approach to cluster randomization trials is relatively well developed, there has been less attention given to the design and analysis of population-averaged models for randomized and non-randomized cluster trials. We provide novel implementations of familiar methods to meet these needs. A design strategy that selects matching control communities based upon propensity scores, a statistical analysis plan for dichotomous outcomes based upon generalized estimating equations (GEE) with a design-based working correlation matrix, and new sample size formulae are applied to a large non-randomized study to reduce underage drinking. The statistical power calculations, based upon Wald tests for summary statistics, are special cases of a general power method for GEE.

Adolescent↗
PubMed2005

Parametric response surface models for analysis of multi-site fMRI data.

Analyses of fMRI brain data are often based on statistical tests applied to each voxel or use summary statistics within a region of interest (such as mean or peak activation). These approaches do not explicitly take into account spatial patterns in the activation signal. In this paper, we develop a response surface model with parameters that directly describe the spatial shapes of activation patterns. We present a stochastic search algorithm for parameter estimation. We apply our method to data from a multi-site fMRI study, and show how the estimated parameters can be used to analyze different sources of variability in image generation, both qualitatively and quantitatively, based on spatial activation patterns.

Algorithms↗
PubMed1979

Determining clinical significance in repeated laboratory measurements. The "Clinical Delta Range".

A study of healthy subjects was conducted at the University of Florida wherein 52 routine clinical laboratory procedures were measured durng normal operation of the clinical laboratories. The goal of the study ws to quantify nonsignificant personal variation for a number of laboratory procedures referred to as a "Clinical Delta Range," which results from taking several samples per day, several days during the week. Results of the statistical test of hypotheses are given together with summary statistics for the 52 different laboratory procedures. A discussion of the model and testing methods are provided. Further, examples are given to illustrate the methodology and certain limitations associated with the concept of a Clinical Delta Range.

Adult↗
PubMed1988

Applications of statistical analysis in diagnostic histopathology and cytopathology.

Corresponding to the rapid increase in the amount of data available for use in clinical diagnoses, there is an increased need for procedures that can provide the diagnostician with meaningful statistical summaries of data and with statements concerning the statistical significance associated with a diagnostic evaluation. It has been demonstrated that multivariate statistical assessment of clinical material can provide consistent, reliable and highly sensitive diagnostic clues, even in instances in which trained personnel are unable to see any change. Several examples of applications of statistical analyses in diagnostic cytology and histopathology are given in this paper. The examples were chosen to be illustrative of the different types of problems for which statistical analyses have been found useful. These problems differ with respect to the extent of the statistical methods thus far developed and the difficulty involved in developing further analyses. For many problems, appropriate statistical analyses are readily available; other problems require definition of custom-made test statistics and, in some cases, also definition of new statistical distributions. The problems discussed here are only a small sample of the existing problems, but they provide at least an indication of the scope of the role that statistics plays in cytopathologic and histopathologic diagnosis.

Cytological Techniques↗
PubMed2002

Antibiotics for trachoma.

BACKGROUND: Trachoma is the world's leading cause of preventable blindness. In 1997 the World Health Organization launched an initiative on trachoma control based on the 'SAFE' strategy (surgery, antibiotics, facial cleanliness and environmental improvement). OBJECTIVES: The aim of this review is to assess the evidence supporting the antibiotic arm of the SAFE strategy by assessing the effects of antibiotics on both active trachoma (primary objective) and on Chlamydia trachomatis infection of the conjunctiva (secondary objective). SEARCH STRATEGY: We searched The Cochrane Controlled Trials Register - CENTRAL/CCTR, which contains the Cochrane Eyes and Vision Group specialised register (Cochrane Library Issue 3, 2001), MEDLINE (1966 to August 2001), and EMBASE (1980 to September 2001). We used the Science Citation Index to look for articles that cited the included studies. We searched the reference lists of identified articles and we contacted authors and experts for details of further relevant studies. SELECTION CRITERIA: We included only randomised trials that satisfied either of two criteria: (a) trials in which topical or oral administration of an antibiotic was compared to placebo or no treatment in people with trachoma, (b) trials in which a topical antibiotic was compared with an oral antibiotic in people with trachoma. A subdivision of particular interest was of trials in which topical tetracycline/chlortetracycline was compared with oral azithromycin, as these are the two World Health Organization recommended treatments. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. We contacted investigators for missing data. MAIN RESULTS: We found 15 studies that randomised a total of 8678 participants. For both outcomes (active trachoma and laboratory evidence of infection) the results of the chi-square tests suggested that there was significant statistical heterogeneity among the trials. There was also marked clinical heterogeneity. No summary statistics were calculated and we therefore present a narrative summary of the results. For the comparisons of oral or topical antibiotic against placebo/no treatment, the data are consistent with there being no effect of antibiotics but are suggestive of a lowering of the point prevalence of relative risk of both active disease and laboratory evidence of infection at three and 12 months after treatment. For the comparison of oral against topical antibiotics the results suggest that oral treatment is neither more nor less effective than topical treatment. REVIEWER'S CONCLUSIONS: There is some evidence that antibiotics reduce active trachoma but results are not consistent and cannot be pooled.

Anti-Bacterial Agents↗
PubMed2005

Antibiotics for trachoma.

BACKGROUND: Trachoma is the world's leading cause of preventable blindness. In 1997 the World Health Organization launched an initiative on trachoma control based on the 'SAFE' strategy (surgery, antibiotics, facial cleanliness and environmental improvement). OBJECTIVES: To assess the evidence supporting the antibiotic arm of the SAFE strategy by assessing the effects of antibiotics on both active trachoma (primary objective) and on Chlamydia trachomatis infection of the conjunctiva (secondary objective). SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library Issue 1, 2005), MEDLINE (1966 to February 2005), and EMBASE (1980 to February 2005). We used the Science Citation Index to look for articles that cited the included studies. We searched the reference lists of identified articles and we contacted authors and experts for details of further relevant studies. SELECTION CRITERIA: We included only randomised trials that satisfied either of two criteria: (a) trials in which topical or oral administration of an antibiotic was compared to placebo or no treatment in people with trachoma, (b) trials in which a topical antibiotic was compared with an oral antibiotic in people with trachoma. A subdivision of particular interest was of trials in which topical tetracycline/chlortetracycline was compared with oral azithromycin, as these are the two World Health Organization recommended treatments. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We contacted investigators for missing data. MAIN RESULTS: We found 15 studies that randomised a total of 8678 participants. For both outcomes (active trachoma and laboratory evidence of infection) the results of the chi squared tests suggested that there was significant statistical heterogeneity among the trials. There was also marked clinical heterogeneity. No summary statistics were calculated and we therefore present a narrative summary of the results. For the comparisons of oral or topical antibiotic against placebo/no treatment, the data are consistent with there being no effect of antibiotics but are suggestive of a lowering of the point prevalence of relative risk of both active disease and laboratory evidence of infection at three and 12 months after treatment. For the comparison of oral against topical antibiotics the results suggest that oral treatment is neither more nor less effective than topical treatment. AUTHORS' CONCLUSIONS: There is some evidence that antibiotics reduce active trachoma but results are not consistent and cannot be pooled.

Administration, Oral↗
PubMedDate not supplied

Cortical localization of human sustained attention: detection with functional MR using a visual vigilance paradigm.

PURPOSE: Our goal was to determine whether functional MRI on a standard 1.5 T system can localize activation during a visual vigilance sustained attention task and whether this corresponds to results described in a PET investigation of a similar task. METHOD: Sixteen volunteers were studied on a 1.5 T system using a gradient echo technique. A single axial section was oriented within a stereotaxic coordinate space, 40 mm superior to the anterior-posterior commissure line. Images with eyes closed were followed by images during subject concentration on a small dim spot. Motion correction and pixel-by-pixel statistical analysis were performed. Talairach grids were applied for summary statistical analysis and comparison to PET data, with analysis using a series of planned contrasts within a repeated measures analysis of variance. RESULTS: Predominantly right-sided frontal and parietal activation was observed, with statistical significance across subjects in the right frontal lobe (F > or = 5.9, p < or = 0.041). Comparison with previously reported PET data yielded a very similar pattern of activation (F = 13.2; df = 1,8; p = 0.007). CONCLUSION: Activation of the right middle frontal gyrus and right parietal lobe during visual vigilance is detectable across functional imaging modalities.

Adult↗
PubMed2000

Summary measures and statistics in the analysis of quality of life data: an example from an EORTC-NCIC-SAKK locally advanced breast cancer study.

Quality of Life (QL) is now included as an endpoint in many phase III cancer clinical trials. Numerous statistical techniques have been presented in the literature to analyse QL data but there is still no agreement as to what is the optimal approach of analysis. In this paper we, therefore, present and compare various techniques which have all appeared in the literature and which may be globally described as summary measures and summary statistics. These techniques are illustrated using data from an EORTC clinical trial in locally advanced breast cancer (EORTC trial 10921). It is also explained in this paper how and when these techniques may be used in other cancer settings. For EORTC trial 10921, it is shown that by choosing different techniques different conclusions may be drawn concerning the QL outcome. This highlights the importance of choosing an appropriate primary statistical method and for describing it a priori in the protocol and analysis plan. In this paper, we show the importance of performing sensitivity or supportive analysis to support conclusions drawn from the primary analysis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

The LEDTOX Necropsy System: an interactive protocol driven gross postmortem examination data collection system.

The LEDTOX Necropsy System consists of a series of programs which provide for the real time collection of gross postmortem data while interacting with the LEDTOX Protocol, Animal Weighing/Clinical Observation, Palpable Mass, Clinical Pathology, Histopathology and Animal Colony Management Systems. Special procedures and lists of tissues specified in the protocol for various necropsy activities drive to data collection routines. Key system features include: system generated gross findings menu to facilitate data entry; designation of key phrases to be used for data summarization; online confirmation of palpable masses identified during life; online review of clinical observation and clinical pathology data. Outputs include: incidence summary of gross postmortem findings; tissue examination/sampling summary; correlation of antemortem and postmortem mass/neoplasm data; organ weight statistical summary. With completion of this module, 90-100% of the routine tables for postmortem reports are immediately available to pathologists for data interpretation.

Animals↗
PubMed2026

A regulatory network underlying idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease in which genetic susceptibility interacts with epithelial, immune, and mesenchymal remodeling. Although the chromosome 11p15.5 locus contains established IPF susceptibility signals near MUC5B and TOLLIP, the broader regulatory architecture of this region remains incompletely resolved. METHODS: We integrated IPF genome-wide association study summary statistics with methylation, expression, and protein quantitative trait loci using summary-data-based Mendelian randomization (SMR). SMR-prioritized candidates were evaluated in independent transcriptomic and methylation cohorts and further contextualized using microRNA, transcription-factor, protein-interaction, machine-learning, single-cell, and spatial transcriptomic analyses. Fibrosis-associated expression patterns were assessed in a bleomycin-induced pulmonary fibrosis rat model. RESULTS: The analyses recovered the established MUC5B and TOLLIP signals and prioritized BRSK2 as a comparatively underexplored candidate supported by eQTL-based SMR and independent molecular evidence. The BRSK2 pQTL association did not pass the HEIDI test and was therefore not interpreted as convergent protein-level genetic evidence. Network analyses linked BRSK2 to cell-cycle, metabolic-stress, and senescence-related programs, while cross-cohort machine learning prioritized FOXA2, CDC25B, and NFE2 as informative network features. Single-cell and spatial analyses localized BRSK2 preferentially to fibroblast and myofibroblast compartments and to regions with greater histological fibrosis severity. In fibrotic rat lungs, BRSK2 expression increased, whereas FOXA2 and CDC25B decreased at the transcript and protein levels. CONCLUSIONS: These findings refine the molecular landscape of the chromosome 11p15.5 IPF susceptibility locus and prioritize BRSK2 as a candidate component of an IPF-associated profibrotic fibroblast state. Its causal contribution, direct regulatory relationships, and therapeutic tractability require targeted mechanistic validation.

Idiopathic Pulmonary Fibrosis↗
PubMed2004

Tegaserod for the treatment of irritable bowel syndrome.

BACKGROUND: IBS is a complex disorder that encompasses a wide profile of symptoms. Current drug treatments for irritable bowel syndrome (IBS) are of limited value. Many target specific symptoms only. Tegaserod, a 5HT(4) partial agonist, represents a novel mechanism of action in the treatment of IBS. OBJECTIVES: The objective of this review was to evaluate the efficacy and tolerability of tegaserod for the treatment of IBS in adults and adolescents aged 12 years and above. SEARCH STRATEGY: MEDLINE 1966-November 2002 and EMBASE 1980-November 2002 were searched. The text and key words used included "tegaserod", "HTF 919", "irritable bowel", and "colonic diseases, functional". The Cochrane Central Register of Controlled Trials, the Inflammatory Bowel Disease Review Group Specialized Trials Register, and Science Citation Index were also searched. Proceedings from the British Society of Gastroenterology Annual Meeting, and Digestive Disease Week (1998-2002) were hand searched. The manufacturer of tegaserod was contacted. Relevant articles were retrieved, and their reference lists were also reviewed. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing tegaserod with placebo, no treatment or any other intervention (pharmacological or non-pharmacological) in subjects aged 12 years and above with a diagnosis of IBS, focusing on clinical endpoints were considered for review. DATA COLLECTION AND ANALYSIS: Study inclusion and exclusion, data extraction and quality assessment was undertaken by two reviewers independently. Meta-analysis was performed where study populations, designs, outcomes, and statistical reporting allowed combination of data in a valid way, using the summary statistic relative risk with 95% CI. Eight short-term placebo-controlled studies fulfilled our inclusion criteria. These were predominantly conducted in women. Seven studies evaluated the efficacy of tegaserod on global gastrointestinal (GI) symptoms in patients with constipation-predominant IBS (C-IBS). One small study evaluated safety in patients with diarrhoea-predominant IBS. MAIN RESULTS: The relative risk (RR) of being a responder in terms of global relief of GI symptoms was significantly higher with tegaserod 12 mg (RR 1.19, 95% CI 1.09, 1.29) and tegaserod 4 mg (RR 1.15, 95% CI 1.02, 1.31) compared with placebo, with a number needed to treat (NNT) of 14 and 20 respectively. When all tegaserod doses were combined and compared with placebo (n=4040), the RR of being a responder was 1.17 (95% CI 1.08, 1.27), with a NNT of 17. Although the pooled results indicate statistically significant benefit with tegaserod, the a priori minimal clinically important differences set in two of the four pooled studies were not reached. Tegaserod did not significantly improve the patients' individual symptoms of abdominal pain and discomfort although bowel habit showed a statistically significant improvement with tegaserod 4 mg and there was a non-significant trend in favour of tegaserod 12 mg. When GI symptoms were assessed separately, those indicative of GI motility such as number of bowel movements and days without bowel movements were generally improved with tegaserod although the proportion of patients experiencing diarrhoea was significantly higher in the tegaserod 12 mg group compared with placebo (RR 2.75, 95% CI 1.90, 3.97), with a number needed to harm (NNH) of 20. Effects of tegaserod on GI symptoms such as bloating, stool consistency, and straining were not consistent across the studies. REVIEWER'S CONCLUSIONS: Tegaserod appears to improve the overall symptomatology of IBS but there are currently few data on its effect on quality of life. In addition, more information is needed about its efficacy in men. It would also be of interest to know whether treatment with tegaserod leads either directly, or indirectly, to changes in visceral sensitivity or psychopathology, which are also considered important in the pathophysiology of this condition.

Adolescent↗
PubMed2004

A comparison of classification methods for differentiating fronto-temporal dementia from Alzheimer's disease using FDG-PET imaging.

Flurodeoxyglucose positron emission tomography (FDG-PET) is being explored to determine its ability to differentiate between a diagnosis of Alzheimer's disease (AD) and fronto-temporal dementia (FTD). We have examined statistical discrimination procedures to help achieve this purpose and compared the results to visual ratings of FDG-PET images. The methods are applied to a data set of 48 subjects with autopsy confirmed diagnoses of AD or FTD (these subjects come from a multi-centre collaborative study funded by the National Alzheimer's Coordinating Center). FDG-PET images are composed of thousands of voxels (volume elements) so one is left with a situation where there are vastly more variables than subjects. Therefore, it is necessary to perform a data reduction before a statistical procedure can be applied. Approaches using both the entire image and summary statistics calculated on a number of volumes of interest (VOI) are examined. We performed the data reduction techniques of principal components analysis (PCA) and partial least-squares (PLS) on the entire image and then used linear discriminant analysis (LDA), quadratic (QDA) or logistic regression (LR) to classify subjects as having AD or FTD. Some of these methods achieve diagnostic accuracy (as assessed by leave-one-out cross-validation) that is similar to visual ratings by expert raters. Methods using PLS appear to be more successful. Averaging or using VOI data may also be helpful.

Alzheimer Disease↗