PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “multiple tests”

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 415 records · Page 23Linked to original sources
PubMed2006

Population-based and family-based association studies of an (AC)n dinucleotide repeat in alpha-7 nicotinic receptor subunit gene and schizophrenia.

The human alpha-7 neuronal nicotinic receptor subunit (CHRNA7) gene, located at chromosome 15q13.2, represents a strong candidate gene for schizophrenia. We have examined an (AC)n dinucleotide repeat in intron 2 of the CHRNA7 gene, which was previously shown to be strongly linked with schizophrenia, using both population-based and family-based association studies. In the population-based study, no significant differences between the genotype and allele frequency distributions in schizophrenia patients and control subjects were observed after correction for multiple testing, although a nominally significant association between the most common allele and schizophrenia was observed (P = 0.023, uncorrected for multiple testing). In the family-based study, there is no significant over-transmission (Transmitted/Non-transmitted: 61/50) of the same allele in 160 family trios. Overall, our results do not support a major role for the (AC)n dinucleotide repeat in schizophrenia susceptibility in Han Chinese. Further large-scale genetic studies based on a set of single nucleotide polymorphisms (SNPs) that fully characterize the linkage disequilibrium patterns at the CHRNA7 gene are necessary to determine the relevance of this gene as a risk factor for schizophrenia susceptibility.

Adult↗
PubMed1999

A perspective on standardizing the predictive power of noninvasive cardiovascular tests by likelihood ratio computation: 1. Mathematical principles.

The current practice of reporting positive and negative predictive value (PV), sensitivity (Se), and specificity (Sp) as measures of the power of noninvasive cardiovascular tests has significant limitations. A test result's PV and its comparison with other test results are highly dependent on the pretest disease prevalence at which it is determined; the citation of sensitivity and specificity provides no succinct or explicit quantitation of the rule-in and rule-out power of a test. This article presents a rationale for the use of an alternative standard for expressing predictive power in the form of positive and negative likelihood ratios, (+)LR and (-)LR. The likelihood ratios are composite expressions of test power, which incorporate the Se and Sp and their respective complements [(1 - Se) and (1 - Sp)], thus yielding single unambiguous measures of positive and negative predictive power. The likelihood ratios are calculated as follows: (+)LR = Se/(1 - Sp) and (-)LR = Sp/(1 - Se). On analysis of the predictive value equations, the likelihood ratios equal the quotients of the posttest predictive value odds to the pretest prevalence odds for disease and no disease, respectively, as follows: (+)LR = (+)PVOd/POD and (-)LR = (-)PVOn/PON, where (+)PVOd is positive predictive value odds for disease, POD is prevalence odds for disease, (-)PVOn is negative predictive value odds for no disease, and PON is prevalence odds for no disease. Thus, the likelihood ratios are measures of the odds advantage in posttest probability of disease or no disease relative to pretest probability, independent of disease prevalence in the tested population. The quotients of the (+)LR or the (-)LR among test results studied in a common population are direct expressions of their relative predictive power in that population. The likelihood ratio principle is applicable to the evaluation of the predictive power of multiple tests performed in a common population and to estimating predictive power at multiple test thresholds.

Confidence Intervals↗
PubMed1986

Intradermal testing with multiple recall antigens for identification of cell-mediated immune deficiency in homosexual men.

In a health screening project for gay men in Stockholm, delayed cutaneous hypersensitivity was tested in 710 men by a commercial kit (Multitest, Mérieux) containing seven recall antigens and related to past hepatitis B virus (HBV) infection, various life style factors, the lymphadenopathy syndrome (LAS), and antibodies to human T-lymphotropic virus type III (HTLV-III). The multiscore (MS: the sum of all positive reactions) was significantly decreased in men with the following characteristics: HBV markers, greater than 50 yearly sexual partners, regular practice of receptive rectal intercourse, regular sex in gay bathhouses, recent sexual encounters in the US, greater than 50 lifetime exposures to inhaled nitrates, LAS, and positive HTLV-III serology. Anergy to tuberculin (TU) but not to any other antigen was more common in men with greater than 20 yearly partners, regular practice of receptive rectal intercourse, exposure to inhalant nitrates, LAS as well as lesser degree of lymphadenopathy, and HTLV-III seropositivity. HTLV-III antibodies were demonstrated in 61 of 416 (14.7%) men. During the 2-year follow-up four men have developed acquired immune deficiency syndrome. All four had MS less than 10 mm and TU anergy. In a BCG-immunized population Multitest only adds marginal information as compared to intradermal testing solely with TU, but may yield prognostic information in evaluating HTLV-III positive individuals with respect to development of manifest AIDS.

AIDS-Related Complex↗
PubMed1999

Successful part-whole perception in young children using multiple-choice tests.

In 3 experiments involving young children (N = 164), excellent perceptual integration of parts and wholes was revealed, unlike findings of earlier Piagetian studies (D. Elkind, R. R. Koegler, & E. Go, 1964). In Experiment 1, 5-year-olds' performance in part-whole perception was raised nearly sixfold when a multiple-choice task was substituted for the Piagetian verbal task used earlier. Performing the multiple-choice first rather than second also raised verbal scores. Experiment 2, with 3- to 5-year-olds, tested whether the children could have been confusing "whole made of parts" with "whole and parts" stimuli. Equal performance was found with 2 versions of a multiple-choice task, including either a whole and parts or a whole and different parts picture, which contradicts the confusion hypothesis. In Experiment 3, with 2- to 4-year-olds, good part-whole perception was demonstrated through the use of a 2-alternative, forced-choice procedure. The lower age bounds for this type of performance are much earlier than hitherto proposed.

Analysis of Variance↗
PubMed2000

Distress in MEN 2 family members and partners prior to DNA test disclosure. Multiple endocrine neoplasia type 2.

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant early-onset cancer disorder. In the Netherlands presymptomatic genetic testing for MEN 2 is offered to testees from the age of five years. We report on adults requesting testing for themselves (n=90) and on parents who want an at-risk child to be tested (n=26). Sociodemographic, personality, and attitude characteristics, and levels of psychological distress, were determined for applicants and their partners in the predisclosure phase of testing. These participants showed only mildly increased levels of psychological distress, defined as heightened scores on measures of general and test-related anxiety, and of psychological complaints. Compared with a normal population, high levels of anxiety and health complaints were found in applicants who were younger than 25 years and single, and in persons who generally tended to react to distressful situations with anxiety or depression. These characteristics were particularly evident in young applicants (<25 years). Our study shows that people who feel ambivalent towards DNA testing and who are more vulnerable to psychological distress are more likely to agree to participate in the test as part of a collective application by members of a hereditary cancer family.

Adolescent↗
PubMedDate not supplied

Bootstrapping of gene-expression data improves and controls the false discovery rate of differentially expressed genes.

The ordinary-, penalized-, and bootstrap t-test, least squares and best linear unbiased prediction were compared for their false discovery rates (FDR), i.e. the fraction of falsely discovered genes, which was empirically estimated in a duplicate of the data set. The bootstrap-t-test yielded up to 80% lower FDRs than the alternative statistics, and its FDR was always as good as or better than any of the alternatives. Generally, the predicted FDR from the bootstrapped P-values agreed well with their empirical estimates, except when the number of mRNA samples is smaller than 16. In a cancer data set, the bootstrap-t-test discovered 200 differentially regulated genes at a FDR of 2.6%, and in a knock-out gene expression experiment 10 genes were discovered at a FDR of 3.2%. It is argued that, in the case of microarray data, control of the FDR takes sufficient account of the multiple testing, whilst being less stringent than Bonferoni-type multiple testing corrections. Extensions of the bootstrap simulations to more complicated test-statistics are discussed.

Analysis of Variance↗
PubMed2004

Fine mapping a gene for pediatric gastroesophageal reflux on human chromosome 13q14.

We previously mapped a gene for severe pediatric gastroesophageal reflux disease ( GERD1) to a 9-cM interval on chromosome 13q14. In this report, we present the results of DNA sequencing and allelic association analyses that were done in an attempt to clone the GERD1 gene. Using a candidate transcript approach, we screened affected individuals for mutations in all transcribed regions of all genes, putative genes, and ESTs identified within the 6.2-Mb GERD1 locus based on alignments with the GenBank cDNA databases. From a total of 50 identifiable genes and 99 EST clusters in the GERD1 locus, we identified 163 polymorphisms (143 SNPs and 20 INDELs) in 21 genes and 37 ESTs. The patterns of inheritance and/or the high population frequencies of all polymorphic alleles identified in this study argued against causative relationships between any of the alleles and the GERD phenotype. Using a subset of 51 SNPs distributed throughout the GERD1 locus, we performed case-control and family (TDT) allelic association analyses on two sets of samples. The case-control study was performed with 73 GERD cases and 93 controls, and the family study was performed using 22 small families. SNP 160 (position 38,925,329 Mb, UCSChg15 map) gave a significant P value prior to multiple test correction in both the case control and family studies, while SNP168 (at 40,442,903 Mb) showed significant association after multiple test correction in the case-control sample, but was uninformative in the family sample. The results suggest that the GERD1 gene might be located near SNP160 or SNP168.

Adult↗
PubMedDate not supplied

Threshold analysis using diagnostic tests with multiple results.

Clinical problems represented by decision trees can be analyzed in terms of the probability threshold model, which provides management recommendations based on the prior probability of disease, the test threshold, and the test-treatment threshold. As originally proposed, the threshold model assumes that diagnostic tests provide information about a single event that is relevant to the decision. For some problems, however, a diagnostic test may provide information about more than one such event (e.g., a computed tomography [CT] scan gives information about both mediastinal and hilar metastases in lung cancer). The authors extend the probability threshold model to cases in which a single test provides information about two events that are relevant to the decision. They derive four thresholds that determine the best strategy for any combination of test results. The approach is illustrated for the decision to use a CT scan to stage lung cancer. The analysis reveals that: 1) the range of prior probabilities for which testing is optimal increases; 2) for some prior probabilities only test results about one event are important; 3) for some prior probabilities test results about both events are important; and 4) failure to account fully for information provided by a test can lead to erroneous test and treatment recommendations.

Bayes Theorem↗
PubMed1977

Associations of hepatitis B surface antigenemia with HLA locus B specificities.

To test whether HLA histocompatibility phenotypes might be associated with circulating hepatitis B surface antigen (HBsAG), we performed chisquare and Scheffé analyses on findings in 144 renal patients with known HLA types and HBsAg status. A significant relation between locus B HLA type (or types) and HBS antigenemia was demonstrated (P = 0.01, adjusted for dual testing) with positive associations suggested between Bw15, Bw17 and Bw35 types and transient or persistent (or both) antigenemia. The latter associations individually were statistically significant only if multiple testing was disregarded, but the contrast by the Scheffé method between the three implicated specificities and all other specificities was significant, even after adjustment for multiple testing (P less than 0.02). Associations of genetically determined HLA specificities with hepatitis B infection may constitute the basis for previously observed population differences in HBS Ag prevalences, and suggest that susceptibility to hepatitis B infection may be in part genetically determined.

Alleles↗
PubMed2003

Multiple patch-test reactions: a pilot evaluation of a combination approach to visualize patterns of multiple sensitivity in patch-test databases and a proposal for a multiple sensitivity index.

BACKGROUND: The variety of patterns of multiple sensitivity in patch-test data remains poorly defined. Studies addressing this topic have primarily concerned the occurrence of pairs of allergens, and some reports hypothesize a predisposing factor that influences the individual sensitivity of patients to multiple reactions. OBJECTIVE: The aim of this study was to address this topic by reanalyzing a matched data set from two patch-test units in Cleveland, OH, and one unit in Cologne, Germany, focusing on multiple reactions to identical allergens of the standard screening trays over the same 4-year period. METHODS: Based on the statistical FREQ procedure (SAS Institute Inc., Cary, NC), we propose a program for addressing the difficulties in computing and visualizing patterns of multiple sensitivity. Additionally, we propose the "multiple sensitivity index" (MSI) as an absolute measure for characterizing the occurrence of an allergen with others on a selected panel. RESULTS: For the seventeen allergens examined, 131072 possible combinations were evaluated in a total of 2881 patients. Of patients tested, 12.4% had multiple positive patch-test reactions to two to seven allergens. However, because of the small number of patients with the crucial number of possible combinations, no cluster patterns were evident in the three- to seven-allergen combinations. Pairs of allergens most frequently observed were nickel sulfate and potassium dichromate (n = 23), formaldehyde and quaternium-15 (n = 18), and nickel sulfate and formaldehyde (n = 13). We found that nickel sulfate, once again the most frequent sensitizer, occurred in the majority of noncombined cases (MSI = -0.280). CONCLUSION: Larger patch-test databases require evaluation to obtain further evidence of cluster patterns of multiple sensitivity and to validate the MSI.

Allergens↗
PubMed2004

An evaluation of laparoscopic cholecystectomy after selective percutaneous transhepatic gallbladder drainage for acute cholecystitis.

BACKGROUND: The aim of this study was to evaluate the safety and usefulness of laparoscopic cholecystectomy after selective percutaneous transhepatic gallbladder drainage in patients with severe acute cholecystitis and patients with acute cholecystitis and severe comorbid disease. METHODS: According to whether percutaneous transhepatic gallbladder drainage was performed before surgery, 133 patients with acute cholecystitis were divided into a percutaneous transhepatic gallbladder drainage group (n=60) and non-percutaneous-transhepatic-gallbladder-drainage group (n=73). Background factors, safety, and postoperative course were retrospectively evaluated and compared between these two groups. RESULTS: Compared with the non-percutaneous-transhepatic-gallbladder-drainage group, the percutaneous transhepatic gallbladder drainage group was significantly older (p=0.0009), had a higher frequency of comorbid disease (p=0.0252), and a worse American Society of Anesthesiology classification (p=0.0021). In individual statistical tests, body temperature (p=0.0288), white blood cell count (p=0.0175), and C-reactive protein value (p=0.0022) were significantly elevated in the percutaneous transhepatic gallbladder drainage group; however, for frequency of comorbid disease, body temperature, and white blood cell count, significance was removed by correction for multiple testing of data. There was no significant difference in gender distribution, history of upper abdominal surgery, or body mass index between the two groups. The duration of surgery was marginally but significantly longer in the percutaneous transhepatic gallbladder drainage group (p=0.0414; in a single statistical test; however, that significance was removed by correction for the multiple testing of data). Between the two groups, there was no significant difference in blood loss at surgery, frequency of postoperative complications, rate of conversion to open laparotomy, interval until oral feeding was resumed, and length of postoperative hospital stay. CONCLUSIONS: These data suggest that satisfactory outcomes can be achieved with selective pre-operative gallbladder drainage in older and sicker patients with acute cholecystitis.

Acute Disease↗
PubMed2006

Statistical methods for expression quantitative trait loci (eQTL) mapping.

Traditional genetic mapping has largely focused on the identification of loci affecting one, or at most a few, complex traits. Microarrays allow for measurement of thousands of gene expression abundances, themselves complex traits, and a number of recent investigations have considered these measurements as phenotypes in mapping studies. Combining traditional quantitative trait loci (QTL) mapping methods with microarray data is a powerful approach with demonstrated utility in a number of recent biological investigations. These expression quantitative trait loci (eQTL) studies are similar to traditional QTL studies, as a main goal is to identify the genomic locations to which the expression traits are linked. However, eQTL studies probe thousands of expression transcripts; and as a result, standard multi-trait QTL mapping methods, designed to handle at most tens of traits, do not directly apply. One possible approach is to use single-trait QTL mapping methods to analyze each transcript separately. This leads to an increased number of false discoveries, as corrections for multiple tests across transcripts are not made. Similarly, the repeated application, at each marker, of methods for identifying differentially expressed transcripts suffers from multiple tests across markers. Here, we demonstrate the deficiencies of these approaches and propose a mixture over markers (MOM) model that shares information across both markers and transcripts. The utility of all methods is evaluated using simulated data as well as data from an F(2) mouse cross in a study of diabetes. Results from simulation studies indicate that the MOM model is best at controlling false discoveries, without sacrificing power. The MOM model is also the only one capable of finding two genome regions previously shown to be involved in diabetes.

Animals↗
PubMed2024

Causal association of menstrual reproductive factors on the risk of osteoarthritis: A univariate and multivariate Mendelian randomization study.

OBJECTIVE: Several observational studies have revealed a potential relationship between menstrual reproductive factors (MRF) and osteoarthritis (OA). However, the precise causal relationship remains elusive. This study performed Mendelian randomization (MR) to provide deeper insights into this relationship. METHODS: Utilizing summary statistics of genome-wide association studies (GWAS), we conducted univariate MR to estimate 2 menstrual factors (Age at menarche, AAM; Age at menopause, AMP) and 5 reproductive factors (Age at first live birth, AFB; Age at last live birth, ALB; Number of live births, NLB; Age first had sexual intercourse, AFSI; Age started oral contraceptive pill, ASOC) on OA (overall OA, OOA; knee OA, KOA and hip OA, HOA). The sample size of MRF ranged from 123846 to 406457, and the OA sample size range from 393873 to 484598. Inverse variance weighted (IVW) method was used as the primary MR analysis methods, and MR Egger, weighted median was performed as supplements. Sensitivity analysis was employed to test for heterogeneity and horizontal pleiotropy. Finally, multivariable MR was utilized to adjust for the influence of BMI on OA. RESULTS: After conducting multiple tests (P<0.0023) and adjusting for BMI, MR analysis indicated that a lower AFB will increase the risk of OOA (odds ratio [OR] = 0.97, 95% confidence interval [CI]: 0.95-0.99, P = 3.39&#xd7;10-4) and KOA (OR = 0.60, 95% CI: 0.47-0.78, P = 1.07&#xd7;10-4). ALB (OR = 0.61, 95% CI: 0.45-0.84, P = 2.06&#xd7;10-3) and Age AFSI (OR = 0.66, 95% CI: 0.53-0.82, P = 2.42&#xd7;10-4) were negatively associated with KOA. In addition, our results showed that earlier AMP adversely affected HOA (OR = 1.12, 95% CI: 1.01-1.23, P = 0.033), and earlier ASOC promote the development of OOA (OR = 0.97, 95% CI: 0.95-1.00, P = 0.032) and KOA (OR = 0.58, 95% CI: 0.40-0.84, P = 4.49&#xd7;10-3). ALB (OR = 0.98, 95% CI: 0.96-1.00, P = 0.030) and AFSI (OR = 0.98, 95% CI: 0.97-0.99, P = 2.66&#xd7;10-3) also showed a negative association with OOA but they all did not pass multiple tests. The effects of AAM and NLB on OA were insignificant after BMI correction. CONCLUSION: This research Certificates that Early AFB promotes the development of OOA, meanwhile early AFB, ALB, and AFSI are also risk factors of KOA. Reproductive factors, especially those related to birth, may have the greatest impact on KOA. It provides guidance for promoting women's appropriate age fertility and strengthening perinatal care.

Humans↗
PubMed1999

Estimating sensitivity and specificity when repeated tests are performed on the same subject.

BACKGROUND: When diagnostic tests are repeated on the same subject, a correlation between test results is expected. This must be taken into account when computing interval estimates. METHODS: The application of regression techniques for correlated data to a logistic model is proposed in order to obtain correct point and interval estimates. RESULTS: The use of different study designs and models of analysis (marginal and 'random effects') is discussed. The advantages of studies using multiple tests, possible sources of bias (including those specific to multiple testing) and methods of correction are also discussed. An example considering Doppler flow velocimetry in pregnancy is presented.

Female↗
PubMed2005

The influence of external ankle braces on subjective and objective parameters of performance in a sports-related agility course.

With lateral ankle sprains being the most frequent sports-related injury, there is an evident demand for the preventive measures in active individuals with chronic ankle instability. Braces are commonly used for prevention and treatment of ankle injuries. Various investigations-mostly performed with healthy subjects-focused on this problem, yet they often compared only a few models or used only limited testing procedures. However, controversy exists whether braces affect sports performance. The purpose of the present study was to compare the effects of ten different ankle braces-one rigid, five semirigid, four soft models-in a comprehensive evaluation with multiple testing procedures in 34 subjects with self-reported chronic ankle instability. The multiple testing procedures evaluated objective performance-related parameters and subjective parameters related to comfort and stability. The subjects performed an agility course with maximal effort. The course included a vertical jump and a cutting maneuver, both on a force platform, a single leg hopping test on level and inclined plates, a combined straight and curve sprint and sidesteps. Three valid trials were measured and averaged for each brace and every subject. Subjective aspects were evaluated with a questionnaire about handling, perceived restrictions, support and comfort; it was completed after each brace was worn and tried. With regard to the objective parameters, no significant differences were found between the braces except for the rigid brace which showed decreased values for the vertical jump and longer times for the other tests compared to all other braces. The subjective evaluation of the braces revealed significant differences with respect to comfort and handling and therefore, permitted a distinction between semirigid and soft braces. Although significant differences between braces were found in subjective performance restriction, no significant differences were revealed in the objective evaluation. From that point of view, patients could choose a brace model according to their individual needs. A comfortable brace might have a positive influence on the athlete's state of mind although other aspects like the brace's stabilizing effect play an additional role and should also be taken into account for recommendation of braces.

Adolescent↗