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 253 records · Page 14Linked to original sources

PubMed1999

Collagen injections for urinary stress incontinence in a small urban urology practice: time to failure analysis of 99 cases.

PURPOSE: We examined the durability of collagen injection response for female incontinence using Kaplan-Meier survival statistics and the log rank test. MATERIALS AND METHODS: A total of 99 women 26 to 84 years old (mean age 60) underwent collagen injections for urethral incompetence. In this retrospective chart audit treatment failures were analyzed using survival statistics. In addition, we conducted a sensitivity analysis of the data using a worst and best case model to account for variability of the data due to the high amount of censored observations. RESULTS: Mean incidence of success was 56% with a mean followup of 9.5 months (95% confidence interval 0.17 to 24.6). Median duration of success was 4.7 months (95% confidence interval 3.4 to 5.9). Of the 10 time to failure function comparisons only cystometric incontinence classification had a statistically significant predictive value for treatment failures (p = 0.003). The survival analysis curve provided a 13% success probability at 18 months and was close to the worst case time to failure function. CONCLUSIONS: Collagen injection has minimal morbidity and a low median success rate. Bladder instability, as determined by cystometrogram, is an important determinant of success. Survival statistics methods should be used more widely to describe urological outcomes because they provide dynamic and, thus, more meaningful information to urologists and patients than summary statistics.

Adult↗

PubMed1991

Analysis of ambulatory blood pressure data.

Many statistical techniques can be used to describe different aspects of ambulatory records, but it is highly unlikely that any single parameter will suffice. A more realistic aim is for a combination of measures that combine statistical validity with physiological meaning and clinical usefulness. This will require compromises between conflicting demands, and only experience and research will ultimately determine the best summary statistics. Some of the available techniques are described here in terms of their value to research and to clinical practice, and an approach is proposed based on considerations of the physiology of blood pressure in free-living man.

Activities of Daily Living↗

PubMed1983

[Forecasting cohort fertility rates by using an exponential function].

"Population forecasts based on cross sectional data do not allow for the variations in cohort fertility. In this paper methods are developed to fit cohort fertility rates by an exponential function. Out of a number of selected functions the Weibull-function shows the best fit. For predicting cohort fertility pattern the parameter values can be derived from the forecasts of a small number of demographic statistics." (summary in ENG)

Birth Rate↗

PubMed2004

Resolution of large and small differences in gene expression using models for the Bayesian analysis of gene expression levels and spotted DNA microarrays.

BACKGROUND: The detection of small yet statistically significant differences in gene expression in spotted DNA microarray studies is an ongoing challenge. Meeting this challenge requires careful examination of the performance of a range of statistical models, as well as empirical examination of the effect of replication on the power to resolve these differences. RESULTS: New models are derived and software is developed for the analysis of microarray ratio data. These models incorporate multiplicative small error terms, and error standard deviations that are proportional to expression level. The fastest and most powerful method incorporates additive small error terms and error standard deviations proportional to expression level. Data from four studies are profiled for the degree to which they reveal statistically significant differences in gene expression. The gene expression level at which there is an empirical 50% probability of a significant call is presented as a summary statistic for the power to detect small differences in gene expression. CONCLUSIONS: Understanding the resolution of difference in gene expression that is detectable as significant is a vital component of experimental design and evaluation. These small differences in gene expression level are readily detected with a Bayesian analysis of gene expression level that has additive error terms and constrains samples to have a common error coefficient of variation. The power to detect small differences in a study may then be determined by logistic regression.

Algorithms↗

PubMed2006

Meta-analysis finds use of inhaled corticosteroids during pregnancy safe: a systematic meta-analysis review.

Inhaled corticosteroids (ICs) are the drug of choice for asthmatic women during pregnancy, but the results on the effects of these medications on obstetrical and perinatal outcomes are not conclusive. Meta-analysis is the statistical analysis of a collection of analysis results from individual studies for the purpose of integrating the findings. Meta-analysis techniques are necessary because only summary statistics are available in the literature. In order to determine the risk of exposure to ICs, we pooled data from all clinical studies that evaluated the pregnancy and perinatal outcomes in women exposed to this group of drugs during pregnancy by the meta-analytic technique. PUBMED, OVID, EMBASE and SCOPUS databases were searched for studies that investigated birth outcome following exposure to ICs during pregnancy. Data were collected from 1997 to 2005 (up to 31 December). Types of outcome investigated were major malformations, preterm delivery, low birth weight and pregnancy-induced hypertension. The criteria for inclusion of studies in this meta-analysis were exposure of women to any therapeutic dosage of any ICs (fluticasone, beclomethasone, budesonide, triamcinolone and flunisolide) during pregnancy. The results showed that ICs do not increase the risk of major malformations, preterm delivery, low birth weight and pregnancy-induced hypertension. In conclusion, ICs do not increase the rates of any obstetrical outcomes investigated in the present study and interestingly improve the symptoms and are helpful in the management of asthma and thus can be used comfortably during pregnancy.

Abnormalities, Drug-Induced↗

PubMed2006

A Bayesian heterogeneous analysis of variance approach to inferring recent selective sweeps.

The distribution of microsatellite allele sizes in populations aids in understanding the genetic diversity of species and the evolutionary history of recent selective sweeps. We propose a heterogeneous Bayesian analysis of variance model for inferring loci involved in recent selective sweeps by analyzing the distribution of allele sizes at multiple loci in multiple populations. Our model is shown to be consistent with a multilocus test statistic, ln RV, proposed for identifying microsatellite loci involved in recent selective sweeps. Our methodology differs in that it accepts original allele size data rather than summary statistics and allows the incorporation of prior knowledge about allele frequencies using a hierarchical prior distribution consisting of log normal and gamma probability distributions. Interesting features of the model are its ability to simultaneously analyze allele size data for any number of populations and to cope with the presence of any number of selected loci. The utility of the method is illustrated by application to two sets of microsatellite allele size data for a group of West African Anopheles gambiae populations. The results are consistent with the suppressed-recombination model of speciation, and additional candidate loci on chromosomes 2 (079 and 175) and 3 (088) are discovered that escaped former analysis.

Alleles↗

PubMed2002

How relevant are the systematic reviews in the cochrane library to emergency medical practice?

STUDY OBJECTIVES: The Cochrane Database of Systematic Reviews (CDSR), one of the databases in the Cochrane Library, is a compilation of regularly updated systematic reviews with meta-analytic summary statistics. We conducted a study of the CDSR to evaluate the relevance of this database to emergency medical practice. METHODS: Using criteria that were determined a priori, 2 reviewers independently screened the titles of 795 completed reviews from the April 2000 CDSR for possible relevance to emergency medicine practice. Five reviewers independently ranked summaries of these reviews for degree of relevance. Agreement was measured using kappa statistics. Disagreements were resolved by consensus or adjudication. RESULTS: Screening of 795 completed reviews identified 136 (17%) as "possibly" and 151 (19%) as "likely" relevant (simple agreement, 74%; kappa=0.82). Further independent assessment indicated 95 (12%) of the 151 "likely" systematic reviews were directly relevant to emergency medicine practice, whereas 44 (6%) were indirectly relevant (simple agreement, 77%; kappa=0.45). Cochrane Review Groups producing the most emergency medicine-relevant systematic reviews included acute respiratory infections (14 [10%]), injuries (14 [10%]), pregnancy and childbirth (13 [10%]), stroke (12 [10%]), and airways (11 [8%]). In contrast, only 1 (0.1%) of the reviews produced by the Heart Review Group was considered directly relevant to emergency medicine practice. CONCLUSION: More than one third of CDSR reviews have some relevance, and 12% are directly relevant, to emergency medical practice or discharge planning. Although certain conditions are well covered, other key emergency medicine areas are not. Emergency physicians should consider the Cochrane Library an important evidence-based resource for emergency medicine therapeutic interventions and should examine ways of increasing the number of reviews relevant to emergency medicine.

Databases, Factual↗

PubMed2005

Statistical tests of the coalescent model based on the haplotype frequency distribution and the number of segregating sites.

Several tests of neutral evolution employ the observed number of segregating sites and properties of the haplotype frequency distribution as summary statistics and use simulations to obtain rejection probabilities. Here we develop a "haplotype configuration test" of neutrality (HCT) based on the full haplotype frequency distribution. To enable exact computation of rejection probabilities for small samples, we derive a recursion under the standard coalescent model for the joint distribution of the haplotype frequencies and the number of segregating sites. For larger samples, we consider simulation-based approaches. The utility of the HCT is demonstrated in simulations of alternative models and in application to data from Drosophila melanogaster.

Chromosome Segregation↗

PubMed2005

Vertebral fracture risk reduction with risedronate in post-menopausal women with osteoporosis: a meta-analysis of individual patient data.

BACKGROUND AND AIMS: The effect of risedronate, a potent pyridinyl bisphosphonate, on vertebral fractures in post-menopausal women was evaluated in randomized, placebo-controlled clinical trials. These trials included two large vertebral fracture studies that used time-to-event methods to evaluate the effects of treatment on fracture risk, thereby allowing both the occurrence and the timing of fractures to be considered. METHODS: We used individual patient data (IPD) and time-to-event methods to perform a meta-analysis of the anti-fracture efficacy of risedronate (2.5 or 5 mg daily) in osteoporotic women enrolled in five double-blind, placebo-controlled clinical trials. Women were included in the analysis if, at baseline, they had either at least one prevalent vertebral fracture or a femoral neck bone mineral density (BMD) T-score of less than -2.5, were at least 1 year post-menopausal, and had had vertebral fracture assessments (N = 3331). RESULTS: Risedronate 5 mg daily reduced the risk of radiographically defined vertebral fracture by 64% (95% CI, 46 to 76%, p < 0.001) in the first year of treatment and 45% (95% CI, 31 to 57%, p < 0.001) in 3 years. The numbers of patients who needed to be treated with risedronate 5 mg to prevent one new vertebral fracture over 1 and 3 years were 21 and 13, respectively. Comparable findings were observed in sub-populations defined on the basis of either prevalent vertebral fracture without regard to femoral neck BMD, or femoral neck BMD without regard to vertebral fracture status. Risedronate significantly reduced the incidence of clinical (symptomatic) vertebral fractures in the first 6 months of treatment (p < 0.001). CONCLUSIONS: This meta-analysis, based upon five trials and using IPD and time-to-event statistical methods, provides a more precise estimate of the effect of risedronate in reducing vertebral fracture risk in postmenopausal osteoporotic women than a meta-analysis using summary statistics from the literature.

Bone Density↗

PubMed2000

Monitoring progress against cancer with age-adjusted rates and trends: what role does the standard population play?

BACKGROUND: Age-adjusted rates and statistical measures used to assess these rates are commonly used in cancer research to monitor progress against this disease. Trends in age-adjusted rates and related summary statistics may depend on the standard population used for age adjustment. Hence, knowledge of how the selected standard population influences such rates is essential for analysis and interpretation of the results. METHODS: The current paper evaluates age-specific and age-adjusted trends for the three leading causes of cancer mortality in the United States: lung and prostate cancers for males, and lung and breast cancers for females. RESULTS, CONCLUSIONS: The analysis shows that the choice of the standard population for age adjustment of the rates can influence one's perception of the progress being made against cancer.

Adult↗

PubMed1996

Teens teach skin cancer prevention.

Cumulative sun exposure has been linked to about 95 percent of all skin cancers. Farmers and their families, by nature of their occupations, are exposed to an abundance of sun over a long period of time and, therefore, are at an increased risk for skin cancer. Because education is known to be a primary means of health, Future Farmers of America (FFA) peer facilitators (teen educators) provided third graders in rural communities sun protection education with the hope that the message would reach the entire family. The FFA facilitators (n = 217) from 39 FFA organizations throughout Wisconsin were trained with skin cancer and sun protection information. The FFA facilitators then gave presentations on sun protection to third graders (n = 2,007) in their school districts. Control schools included 57 facilitators and 669 third graders. Evaluation involved pre-, post-, and six-month follow-up surveys testing knowledge gained by the third graders. Students who correctly responded to a question on the post-survey after incorrectly answering it on the pre-survey were said to have had a knowledge gain for that question. By using chi-square tests, the intervention group demonstrated a statistically significant (P < 0.001) higher proportion of students experiencing knowledge gain than did the control group from pre- to post-surveys for nine of the 10 questions. Summary statistics were used to describe the study population. In addition to skin cancer knowledge questions, the survey of facilitators included sun protection behavior and attitude questions. This intervention was able to use peer educators as instructors to demonstrate knowledge gain in the youths of the target population. The pilot project materials costs were +0.55 per third grade student and +3.50 per facilitator. Using a school-based organization such as FFA provided a cost-effective means of reaching the rural population.

Adolescent↗

PubMed1993

Bladder cancer and coffee drinking: a summary of case-control research.

An association between coffee drinking and cancer of the lower urinary tract (LUT) was first suggested 20 years ago and has been the subject of many epidemiological studies. We have undertaken a critical review and statistical summary of 35 case-control studies of this association published between 1971 and 1992. Predefined methodological criteria were applied to the available reports. Studies were classified as either meeting the criteria (core studies) or failing to satisfy at least one of the requirements for design or analysis (non-core studies). The summarised data from the 8 core studies showed no evidence of an increase in risk of LUT cancer with coffee drinking in men or women after adjustment for the effects of cigarette smoking (odds ratio 1.07 [95% CI 1.00-1.14] for men, 0.91 [0.81-1.03] for women). The measures of association from the non-core studies were higher on average than those from the core studies, although the inclusion of these data in an overall summarised estimate did not substantially change the findings from the core analysis. We conclude that the best available data do not suggest a clinically important association between the regular use of coffee and development of cancer of the LUT in men or women.

Case-Control Studies↗

PubMed1989

Extended relational operators for statistical data manipulations in medical databases.

Conventional relational database management systems fail to address three features of statistical data management in a biomedical/clinical database, namely, that (1) statistical and medical data (SMD) require a great deal of space and need to be stored in a reduced form with minimal duplication; indeed, SMD have many derived/calculated and summary statistics that make the number of attributes in a relation (i.e., a set of records) grow rapidly and dynamically; (2) most SMD have hierarchical structures that are difficult to manage using the relational data model since SMD are stored in separate relations for duplication and space considerations; and (3) the management of SMD is made easier if it is possible to reorganize relations or group data, a capability lacking in conventional relational database management systems. In this paper, we (1) introduce five extended relational operators, (lattice) NEST, (lattice) UNNEST, MERGE, SPREAD, and GEN, to reorganize relations; (2) integrate the extended operators with conventional relational algebra and introduce the concept of the lattice relational model; and (3) give applications of the extended relational operators and the lattice relational model in solving the problems of statistical data manipulation in medical databases.

Database Management Systems↗

PubMed2026

Identification and genetic validation of potential therapeutic targets for pulmonary hypertension through multi-omics causal inference.

Pulmonary hypertension (PH) underscores the urgent need for novel therapeutic targets. This study aimed to employ a proteome-wide Mendelian randomization (MR) approach to systematically identify circulating proteins causally associated with PH, thereby providing genetically validated candidate targets for drug development. We adopted a 2-sample MR design, integrating large-scale plasma proteomic quantitative trait loci (pQTL) data (encompassing 4148 proteins) and summary statistics from a large-scale PH genome-wide association study (2047 cases, 8301 controls). Candidate targets were screened through a multilayered analytical pipeline comprising proteomic MR, transcriptomic MR, and summary-data-based Mendelian randomization. The ultimately identified MR-Identified Causal Candidate Targets (MR-ICTs) underwent rigorous Bayesian colocalization analysis, followed by biological characterization through functional enrichment analysis, single-cell transcriptomics, and phenome-wide association studies. Through robust genetic causal inference, this study provides that circulating proteins such as LYZ, GREM2, NID1, and PF4V1 play causal roles in PH pathogenesis. These findings offer a set of rigorously genetically validated, high-priority therapeutic targets for developing novel PH treatments, specifically addressing key pathological mechanisms such as innate immunity, BMP signaling pathway dysregulation, and platelet activation. Our multi-dimensional analysis ultimately identified 6 MR-ICTs causally associated with PH. Notably, the causal associations for lysozyme C (LYZ), gremlin-2 (GREM2), nidogen-1 (NID1), and platelet factor 4 variant 1 (PF4V1) were stringently validated by Bayesian colocalization analysis (posterior probability for hypothesis 4 [PPH4], indicating a shared causal variant, > 0.99). Functional enrichment analysis revealed significant involvement of these targets in immune response and TGF-β signaling pathways. Single-cell analysis further elucidated their cell-type-specific expression, with LYZ predominantly expressed in monocytes and PF4V1 almost exclusively in platelets.

Hypertension, Pulmonary↗

PubMed2026

Programmed cell death and risk of diabetic retinopathy: a Mendelian randomization study.

BACKGROUND: Programmed cell death (PCD) plays an important role in diabetic retinopathy (DR); however, the underlying genetic mechanisms remain unclear. We used Mendelian randomization (MR) to investigate the causal relationships between PCD-related genes and DR. This study aimed to investigate the effects of PCD on the risk of DR by conducting MR analysis. METHODS: Summary statistics from gene expression quantitative trait loci (eQTL) studies (31,684 Europeans) were analyzed. Genetic instrumental variables were selected using cis-eQTL single-nucleotide polymorphisms (SNPs; P < 5 × 10- 8). Summary data-based MR (SMR) was employed to assess causal associations between PCD-related genes and DR, with three additional MR methods used for sensitivity testing. Bayesian colocalization was used to examine the shared regulatory mechanisms between PCD QTLs and DR risk loci. RESULTS: Sensitivity and colocalization analyses revealed six genes that affected DR: cathepsin H (CTSH), NAD(P)H: quinone oxidoreductase 1 (NQO1), tribbles pseudokinase 3 (TRIB3), and phosphoglycerate mutase 5 (PGAM5), which increased DR risk, and iron-responsive element binding protein 2 (IREB2) and tumor necrosis factor (TNF), which exhibited protective effects. Multivariate MR confirmed significant causal effects for CTSH, IREB2, and PGAM5 (p < 0.050). Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis (including 10 STRING-derived genes) revealed that 13 genes were enriched in necroptosis, apoptosis, mitophagy, and TNF signaling pathways in DR. CONCLUSIONS: This MR study supports the causal involvement of PCD in DR and identifies candidate genes (CTSH, IREB2, PGAM5, NQO1, TRIB3, and TNF) for therapeutic targeting or biomarker development in DR prevention or diagnosis.

Humans↗

PubMed1994

Regionalized delivery and variable utilization of coronary artery bypass grafting in Ontario from 1981 to 1991.

OBJECTIVE: To analyse the geographic variation in the rates of coronary artery bypass grafting (CABG) between 1981 and 1991. DESIGN: Retrospective study of discharge abstracts (from the provincial hospital discharge database) for odd fiscal years. SETTING: Ontario. PARTICIPANTS: All Ontario residents undergoing CABG between 1981 and 1991. OUTCOME MEASURES: Age- and sex-standardized median, maximum and minimum (plus 25th and 75th percentile) rates of CABG per 100,000 population aged 20 years and over, as well as interregional variation. RESULTS: The median rate of CABG rose from 46.2 to 72.7 per 100,000 adults between 1981 and 1991. The minimum rate varied from 1.9 to 12.4 per 100,000 and the maximum rate from 110.4 to 172.1 per 100,000 during the study period. Variations in the area-specific rates were significant in all years (p < 0.0001, based on the likelihood ratio chi 2 test after adjustment for age and sex). None of the four summary statistical measures showed any obvious diminution between 1981 and 1989, nor was there a change in the utilization pattern during the waiting-list crisis years of 1987 and 1989. However, the summary measures did reach their lowest level in 1991. The relative consistency of local practice patterns was tested by means of ranking area-specific rates and comparing the rankings for different years. Correlation coefficients varied from 0.50 to 0.82 (p < 0.0001); the correlation coefficient for 1991 on 1981 was 0.61 (p < 0.0001). CONCLUSIONS: Consistent and marked variations in the use of CABG existed across the counties of Ontario from 1981 to 1991. Despite a major expansion in provincial caseload capacity and planned regionalization of CABG as a surgical service, incremental resources were apparently not allocated in a manner that reduced interregional discrepancies.

Coronary Artery Bypass↗

PubMed1997

Quantitative and spatial information on the composition of chimaeric fetal mouse eyes from single histological sections.

The spatial distribution of cells in chimaeric tissues, composed of two genotypes, provides insights into the extent of cell mixing during development and growth. However, direct measurement of patch sizes is not usually meaningful because, when the proportion of one genotype is high, a single patch may encompass several adjacent coherent clones of like genotype (clone aggregation). Two previously used methods of comparing patch lengths were evaluated to overcome this problem. The corrected mean patch length (corrected for the predicted effects of random clone aggregation) is a more useful summary statistic than the median patch length of the minor genotype, because its use is not restricted to grossly unbalanced chimaeras, but its validity has been questioned. The two methods gave almost identical numerical summaries of patch sizes in the retinal pigment epithelium of fetal chimaeras, thereby validating the use of the corrected mean patch length for this tissue. The present study also showed that the corrected patch length was unaffected by the presence of cells hemizygous for the TgN(Hbb-b1)83Clo transgene and that the proportion of pigmented cells in a single histological section was representative of the overall composition of the chimaeric fetus.

Animals↗

PubMed2003

Statistical analysis of intramembranous particles using freeze fracture specimens.

We studied the point processes of intramembranous particles of mitochondrial membranes from HeLa cells using the freeze fracture technique. Three groups - under normal conditions, after exposition with rotenone, and after exposition with sodium acid - were compared. First, we used several summary statistics in order to study the two-dimensional point patterns of intramembranous particles within each group. Then, we compared the patterns in different groups by bootstrap tests using the K-function and the nearest neighbour distance function G(r). Estimation of the G-function provided significant results but no significant differences between groups were found using the classical K-function; estimation of G(r) should therefore not be omitted when studying observed planar point patterns.

Data Interpretation, Statistical↗