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PubMed1996

HIV testing behaviors in a population of inner-city women at high risk for HIV infection.

The relationship between HIV testing history. HIV serostatus, and risk behaviors was examined to investigate factors associated with obtaining an HIV test, returning for results, or receiving multiple tests. Seven hundred and five volunteers for an HIV study were questioned about prior HIV testing, drug and sexual practices, and sociodemographic characteristics. Women who reported a prior HIV test were compared with those without a previous test, women who returned for test results were compared with those not returning; and women who reported multiple tests were compared with those having only one test. Seventy-five percent of the women reported a prior test; 12% had not returned for test results; 46% reported multiple tests. Women reporting higher levels of HIV risk behaviors were more likely to have been tested and to return for results. Injection drug use and having four or more sex partners were significantly associated with repeated HIV testing. Over one third of the women with substantial HIV risk practices had not been HIV tested or failed to obtain test results. Women who obtained multiple HIV tests were more likely to report high-risk practices in spite of having received risk counseling with repeated testing.

AIDS Serodiagnosis↗
PubMed1995

Ambulatory blood pressure monitoring and cardiovascular function tests in multiple system atrophy.

Cardiovascular tests (CT) of autonomic function and non-invasive ambulatory blood pressure (BP) and heart rate (HR) monitoring were performed in 17 patients with multiple system atrophy (MSA) (mean age 61 +/- 9 years) and in 12 healthy subjects matched for sex and age. CT showed severe autonomic dysfunction with orthostatic hypertension (OH) in eight patients with MSA (47%) (Group I). The remaining nine out of the 17 patients didn't show BP abnormalities during CT but an impaired HR reflex response was found (Group II). BP monitoring showed a reversed circadian BP rhythm in Group I with higher night-time than day-time values, a blunted circadian BP pattern in Group II and a normal day-night BP reduction in controls. Day-night HR reduction was poor in Group II and absent in Group I. Post-prandial hypotension was evaluated after a standard meal. In Group I systolic/diastolic BP fell within 30 minutes after meal (from 135 +/- 16/89 +/- 13 to 118 +/- 17/73 +/- 12 mmHg; p < 0.05) and after two hours had not returned to basal levels. In Group II a reduction of only systolic BP was found within 45 minutes after meal and persisted for one hour. OH clinically identifies a subgroup of MSA patients with a more severe BP dysregulation characterized by severe post-prandial hypotension and reversed circadian BP rhythm. CT and ambulatory BP monitoring are useful tools in identifying early stage of cardiovascular autonomic impairment.

Adult↗
PubMed2001

Bayesian approaches to modeling the conditional dependence between multiple diagnostic tests.

Many analyses of results from multiple diagnostic tests assume the tests are statistically independent conditional on the true disease status of the subject. This assumption may be violated in practice, especially in situations where none of the tests is a perfectly accurate gold standard. Classical inference for models accounting for the conditional dependence between tests requires that results from at least four different tests be used in order to obtain an identifiable solution, but it is not always feasible to have results from this many tests. We use a Bayesian approach to draw inferences about the disease prevalence and test properties while adjusting for the possibility of conditional dependence between tests, particularly when we have only two tests. We propose both fixed and random effects models. Since with fewer than four tests the problem is nonidentifiable, the posterior distributions are strongly dependent on the prior information about the test properties and the disease prevalence, even with large sample sizes. If the degree of correlation between the tests is known a priori with high precision, then our methods adjust for the dependence between the tests. Otherwise, our methods provide adjusted inferences that incorporate all of the uncertainty inherent in the problem, typically resulting in wider interval estimates. We illustrate our methods using data from a study on the prevalence of Strongyloides infection among Cambodian refugees to Canada.

Bayes Theorem↗
PubMed2004

The effects of enforced, rapid deceleration on performance in a multiple sprint test.

The nature of multiple sprint sports such as soccer, hockey, and rugby is such that deceleration plays an important part in the movement patterns of players during a game and training. The purpose of this study was to investigate the effect of deceleration on fatigue during repeated sprint efforts. A group of 18 elite field hockey players (all men) performed a running repeated sprint ability test (6 x 40 m using maximal effort and departing every 30 seconds). In one condition, there was no deceleration zone, and in the second condition, the test had a deceleration component (rapid deceleration to a stop within 6 m of the end of each sprint). Sprint times under each condition were compared using a repeated-measures analysis of variance. No significant difference was seen between the 2 conditions for mean sprint times (p > 0.05) or for the mean fatigue index (p > 0.05). However, results showed a divergent trend, and further analysis extrapolating the data for an increased number of sprints showed that a significant difference (p < 0.05) would have been seen at the 11th sprint. Although this study found that the deceleration zone had little effect on the 6-sprint protocol, it was clear that the deceleration component would have shown an effect, giving rise to greater fatigue and slower sprint times, if the number of sprints had been increased. The implications are that deceleration training should be introduced into general fitness training programs for those competing in multiple sprint sports.

Adult↗
PubMed1990

More powerful procedures for multiple significance testing.

The problem of multiple comparisons is discussed in the context of medical research. The need for more powerful procedures than classical multiple comparison procedures is indicated. To this end some new, general and simple procedures are discussed and demonstrated by two examples from the medical literature: the neuropsychologic effects of unidentified childhood exposure to lead, and the sleep patterns of sober chronic alcoholics.

Alcoholism↗
PubMed1976

The linoleic acid depression (LAD) test for multiple sclerosis using the macrophage electrophoretic mobility (MEM) test.

With the macrophage electrophoretic mobility (MEM) test of Field & Caspary, lymphocyte sensitization to thyroid antigen (F1-fraction) is demonstrable in all subjects--multiple sclerosis (MS) patients, those with other (destructive) neurological diseases (OND) and normals. The MEM-LAD test enables a further differentiation to be made in neurological patients compared ot normals: Linoleic acid inhibits the positive result by about 95 per cent in the case of MS, 58 per cent in normals and 45 per cent in OND. The high reduction appears to be a characteristic of MS. It is seen at all stages and in all forms of the disease and is not materially influenced by moderate immunosuppressive therapy. The mothers of MS patients show an intermediate result of about 78 per cent, suggesting a familial (genetic) background to the metabolic phenomenon described here; there is, however, evidence of an added exogenic factor for the development of the disease. The theoretical basis of the LAD test suggests further therapeutic trials of linoleic acid in treatment of MS.

Adolescent↗
PubMed2004

A tree based lack-of-fit test for multiple logistic regression.

Several omnibus tests have been developed to assess the fit of a regression model. But many of these lack-of-fit tests focus on the simple regression setting. Here, we focus on multiple logistic regression. Pearson's well-known chi-square test statistic and the deviance statistic are no longer valid in the case that the model contains one or more continuous covariates. To overcome this difficulty, Hosmer and Lemeshow proposed a Pearson type statistic based on groups defined by the so-called deciles of risk. We propose a test statistic that is similar in approach to the Hosmer and Lemeshow statistic in that the observations are classified into distinct groups. In the procedure proposed here however, the grouping is not according to probabilities fitted under the null model. We use a recursive partitioning algorithm to divide the sample space into different groups. This generally allows for a more powerful assessment of the model fit. Simulations are carried out to compare the results of the proposed test to that of Hosmer and Lemeshow. Three data examples illustrate the performance of the tree based lack-of-fit test, in comparison to several other tests.

Adult↗
PubMed1977

[The advantages of multiple choice tests in undergraduate teaching of pharmacology (author's transl)].

Multiple-choice tests in pharmacology were carried out with students who had no previous experience in this kind of examination. The curriculum in pharmacology was divided into four parts. Each part was followed by a test consisting of 90 questions. A special arrangement was made for those students who voluntarily participated in all four tests during academic year. Pass marks in all four completed tests were considered equivalent to a successful outcome in the one oral examination which is, at present, obligatory. In order to encourage a high level of participation amongst the students, failure in one or more of the tests had no adverse consequences. As a result, a markedly increased attendance at lectures, as well as a positive feed back of information for the faculty, were ascertained and assessment of the efficiency of the teaching methods facilitated. Application of multiple choice tests to the teaching of Pharmacology to undergraduate students proved to be recommendable, both as a test procedure and of advantage in the actual learning process.

Austria↗
PubMed2006

An efficient family-based association test using multiple markers.

In genetic association studies, multiple markers are usually employed to cover a genomic region of interest for localizing a trait locus. In this report, we propose a novel multi-marker family-based association test (T(LC)) that linearly combines the single-marker test statistics using data-driven weights. We examine the type-I error rate in a numerical study and compare its power to identify a common trait locus using tag single nucleotide polymorphisms (SNPs) within the same haplotype block that the trait locus resides with three competing tests including a global haplotype test (T(H)), a multi-marker test similar to the Hotelling-T(2) test for the population-based data (T(MM)), and a single-marker test with Bonferroni's correction for multiple testing (T(B)). The type-I error rate of T(LC) is well maintained in our numeric study. In all the scenarios we examined, T(LC) is the most powerful, followed by T(B). T(MM) and T(H) are the poorest. T(H) and T(MM) have essentially the same power when parents are available. However, when both parents are missing, T(MM) is substantially more powerful than T(H). We also apply this new test on a data set from a previous association study on nicotine dependence.

Family↗
PubMed1987

Isomorphic patient management problems: a method of creating equivalent problem-solving tests.

Multiple choice format pre- and post-tests have a high likelihood of being equivalent (i.e. parallel) if well-known guidelines are followed. In the absence of such guidelines for pre- and post-tests of problem-solving, the authors devised a simple method of creating problems that are likely to be equivalent. The method was employed with patient management problems (PMPs) and focuses on maintaining the same form or structure of the problems while making the problems appear different to the examinee. Such problems are 'isomorphic'. The equivalence or parallelism of 10 PMPs with their isomorphic counterparts was demonstrated. The method for creating isomorphic PMPs appears to be applicable for creating equivalent pre- and post-tests composed of problems other than PMPs.

Education, Medical↗
PubMed2003

Testing of multiple samples increases the sensitivity of stool decay-accelerating factor test for the detection of colorectal cancer.

OBJECTIVES: We previously reported that the measurements of stool decay-accelerating factor (DAF), a membrane-bound, complement regulatory protein, may be valuable for the detection of colorectal cancer. Recently we have refined the immunoassay for stool DAF. In the present study, using the refined assay, we measured stool DAF concentrations in multiple samples from patients with colorectal cancer and in healthy controls to determine whether testing of multiple samples would increase the sensitivity of the stool DAF test. METHODS: DAF was measured in three spontaneously passed stool samples from each of 100 patients with colorectal cancer and 100 control subjects without apparent colorectal disease. RESULTS: The stool DAF concentrations in the patients with colorectal cancer (median 11.1 ng/g stool; interquartile range 2.9-32.7 ng/g) were significantly higher than concentrations in the subjects without colorectal diseases (median 1.6 ng/g stool; interquartile range 0.4-3.4 ng/g) (p<0.0001). Testing of two samples from each patient significantly increased the sensitivity (72%) of the stool DAF test without significantly decreasing its specificity (92%). The stool DAF test was positive in more than one half of patients with colorectal cancer at a relatively early TNM stage or with negative fecal occult blood test. CONCLUSIONS: These findings suggest that stool DAF is a marker of colorectal cancer independent of fecal occult blood and testing of two samples increases the sensitivity of the stool DAF test. Measurement of stool DAF now seems worthy of further consideration as a noninvasive method for the detection of colorectal cancer.

Adult↗
PubMed1980

Serial electrophysiologic testing of multiple drugs in patients with atrioventricular nodal reentrant paroxysmal tachycardia.

Serial electrophysiologic testing of multiple drugs was performed in 21 patients with recurrent atrioventricular (AV) nodal reentrant paroxysmal supraventricular tachycardia (PSVT). All patients had reproducible sustained PSVT induced before drug administration. Serial daily PSVT induction was attempted after administration of i.v. ouabain (0.01 mg/kg) (16 patients), i.v. propranolol (0.1 mg/kg (17 patients), i.v. ouabain + propranolol (same dosages) (12 patients), i.v. procainamide (600-1000 mg) (17 patients) and oral quinidine (1600-2400 mg/day) (nine patients). In two of 21 patients (10%), no tested drug prevented induction of sustained PSVT. In 19 of 21 patients (90%), one or more drugs prevented induction of sustained PSVT: ouabain--seven patients, propranolol--seven patients, ouabain + propranolol--seven patients, procainamide--11 patients, quinidine--seven patients. The site of action of ouabain and/or propranolol was either the antegrade limb or the retrograde limb (RL) of the circus movement. The site of action of procainamide or quinidine was always the RL. These 19 patients were treated with oral drugs, based on results of serial testing. Eighteen patients were successfully followed for 6-50 months. In 13 of these 18 patients PSVT did not recur. Two patients (11%) had > 95% reduction in frequency of PSVT recurrences, and three (17%) did not respond to chosen oral drugs. Serial electrophysiologic testing of multiple drugs is feasible in patients with AV nodal reentrant paroxysmal tachycardia. Drug responses are variable. In most but not all patients, serial electrophysiologic testing defines effective prophylactic drug therapy. This method of defining prophylactic drug therapy appears most suitable for patients with poorly tolerated tachycardias that occur only sporadically.

Administration, Oral↗
PubMed1983

Persistent neurological deficit precipitated by hot bath test in multiple sclerosis.

For a half century, the hot bath test has been used as a "diagnostic test" in multiple sclerosis. The appearance of new neurological signs or aggravation of preexisting signs generally is transient, with resolution on return of body temperature to normal. We have observed four patients, however, with considerable and prolonged neurological debilitation after hot bath testing. We suggest caution in the application of such testing.

Adult↗