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  • 1
    Online Resource
    Online Resource
    Asymptotic properties of the two one-sided t -tests – new insights and the Schuirmann-constant
    Walter de Gruyter GmbH ; 2022
    In:  The International Journal of Biostatistics Vol. 18, No. 1 ( 2022-06-01), p. 19-38
    Details
    In: The International Journal of Biostatistics, Walter de Gruyter GmbH, Vol. 18, No. 1 ( 2022-06-01), p. 19-38
    Abstract: The two one-sided t -tests (TOST) method is the most popular statistical equivalence test with many areas of application, i.e., in the pharmaceutical industry. Proper sample size calculation is needed in order to show equivalence with a certain power. Here, the crucial problem of choosing a suitable mean-difference in TOST sample size calculations is addressed. As an alternative concept, it is assumed that the mean-difference follows an a-priori distribution. Special interest is given to the uniform and some centered triangle a-priori distributions. Using a newly developed asymptotical theory a helpful analogy principle is found: every a-priori distribution corresponds to a point mean-difference, which we call its Schuirmann-constant. This constant does not depend on the standard deviation and aims to support the investigator in finding a well-considered mean-difference for proper sample size calculations in complex data situations. In addition to the proposed concept, we demonstrate that well-known sample size approximation formulas in the literature are in fact biased and state their unbiased corrections as well. Moreover, an R package is provided for a right away application of our newly developed concepts.
    Type of Medium: Online Resource
    ISSN: 1557-4679
    URL: Article
    DOI: 10.1515/ijb-2020-0057
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2239443-6
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  • 2
    Online Resource
    Online Resource
    Risk Factors for Severe Hemorrhagic Transformation in Ischemic Stroke Patients Treated With Recombinant Tissue Plasminogen Activator : A Secondary Analysis of the European-Australasian Acute Stroke Study (ECASS II)
    Ovid Technologies (Wolters Kluwer Health) ; 2001
    In:  Stroke Vol. 32, No. 2 ( 2001-02), p. 438-441
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 32, No. 2 ( 2001-02), p. 438-441
    Abstract: Background and Purpose —Intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA) improves the outcome for ischemic stroke patients who can be treated within 3 hours of symptom onset. The efficacy of thrombolysis has been demonstrated despite an increased risk of severe hemorrhagic transformation (HT) in patients treated with rtPA. We performed an analysis of risk factors for severe HT in the second European-Australasian Acute Stroke Study (ECASS II). Methods —HTs were classified by using clinical and radiological criteria as follows: hemorrhagic infarction (HI), parenchymal hemorrhage (PH), and symptomatic intracranial hemorrhage (SICH). Potential risk factors for HT were tested by stepwise logistic regression analysis, including rtPA-by-variable interactions. In addition, the distribution of bad outcome (modified Rankin score 5 to 6) at day 90 was stratified according to each category of HT. Results —PH and SICH but not HI were associated with rtPA. Also, PH and SICH but not HI were more severe in rtPA-treated patients than in those receiving placebo. Risk factors for PH were rtPA, extent of parenchymal hypoattenuation on baseline CT, congestive heart failure, increasing age, and baseline systolic blood pressure. The risk of PH on rtPA was increased in older patients and in those who were treated with aspirin before thrombolysis. Risk factors for SICH were rtPA, congestive heart failure, extent of parenchymal hypoattenuation, and increasing age. The risk of SICH on rtPA was increased in patients who were treated with aspirin before thrombolysis. Conclusions —This secondary analysis of ECASS II has confirmed the importance of the extent of hypoattenuation as a risk factor for severe HT. The findings also suggest that older patients and those who have used aspirin before stroke are at higher risk of a severe HT on rtPA.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.32.2.438
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2001
    detail.hit.zdb_id: 1467823-8
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  • 3
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    Online Resource
    Effects of Alteplase for Acute Stroke on the Distribution of Functional Outcomes : A Pooled Analysis of 9 Trials
    Ovid Technologies (Wolters Kluwer Health) ; 2016
    In:  Stroke Vol. 47, No. 9 ( 2016-09), p. 2373-2379
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 47, No. 9 ( 2016-09), p. 2373-2379
    Abstract: Thrombolytic therapy with intravenous alteplase within 4.5 hours of ischemic stroke onset increases the overall likelihood of an excellent outcome (no, or nondisabling, symptoms). Any improvement in functional outcome distribution has value, and herein we provide an assessment of the effect of alteplase on the distribution of the functional level by treatment delay, age, and stroke severity. Methods— Prespecified pooled analysis of 6756 patients from 9 randomized trials comparing alteplase versus placebo/open control. Ordinal logistic regression models assessed treatment differences after adjustment for treatment delay, age, stroke severity, and relevant interaction term(s). Results— Treatment with alteplase was beneficial for a delay in treatment extending to 4.5 hours after stroke onset, with a greater benefit with earlier treatment. Neither age nor stroke severity significantly influenced the slope of the relationship between benefit and time to treatment initiation. For the observed case mix of patients treated within 4.5 hours of stroke onset (mean 3 hours and 20 minutes), the net absolute benefit from alteplase (ie, the difference between those who would do better if given alteplase and those who would do worse) was 55 patients per 1000 treated (95% confidence interval, 13–91; P =0.004). Conclusions— Treatment with intravenous alteplase initiated within 4.5 hours of stroke onset increases the chance of achieving an improved level of function for all patients across the age spectrum, including the over 80s and across all severities of stroke studied (top versus bottom fifth means: 22 versus 4); the earlier that treatment is initiated, the greater the benefit.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/STROKEAHA.116.013644
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2016
    detail.hit.zdb_id: 1467823-8
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  • 4
    Online Resource
    Online Resource
    Thrombolysis in Stroke Despite Contraindications or Warnings?
    Ovid Technologies (Wolters Kluwer Health) ; 2013
    In:  Stroke Vol. 44, No. 3 ( 2013-03), p. 727-733
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 44, No. 3 ( 2013-03), p. 727-733
    Abstract: Intravenous thrombolysis with alteplase is approved for acute ischemic stroke, but its use is limited by numerous contraindications and warnings arising from trial selection criteria or expert opinions. We examined outcomes from alteplase-treated versus untreated patients, registered in a trials archive, according to presence or absence of specified contraindications and warnings. Methods— We analyzed 90-day modified Rankin Scale across the whole distribution of scores using the Cochran–Mantel–Haenszel test, with adjustment for age and baseline National Institutes of Health Stroke Score, followed by proportional odds logistic regression analysis to estimate the odds ratios for preferred outcome. Results— We used data from 9613 ischemic stroke patients of whom 2755 were treated with thrombolysis. Adjusted odds ratios showed a broad trend of more favorable 3-month outcome associated with alteplase treatment versus no treatment in various subgroups of patients with contraindications and warnings; for example, 1.40 (95% confidence interval [CI], 1.14–1.70) in patients aged 〉 80 (n=1805), 1.50 (95% CI, 1.03–2.18) in patients with combined history of prior stroke and diabetes mellitus (n=672), 1.42 (95% CI, 1.19–1.70) in patients on prior single antiplatelet agent (n=1626), 2.20 (95% CI, 1.12–4.32) in patients on oral anticoagulation, and International Normalized Ratio≤1.7 (n=157), 1.50 (95% CI, 1.15–1.97) in patients with baseline glucose 〉 180 (n=879), and 1.57 (95% CI, 1.12–2.18) in patients with pretreatment National Institutes of Health Stroke Score 〉 22 (n=620). Conclusions— This comprehensive retrospective analysis of various contraindications and warnings provides reassurance about benefits and risks of intravenous alteplase treatment in common clinical situations.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/STROKEAHA.112.674622
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2013
    detail.hit.zdb_id: 1467823-8
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  • 5
    Online Resource
    Online Resource
    Alteplase for Acute Ischemic Stroke in Patients Aged 〉80 Years : Pooled Analyses of Individual Patient Data
    Ovid Technologies (Wolters Kluwer Health) ; 2020
    In:  Stroke Vol. 51, No. 8 ( 2020-08), p. 2322-2331
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 51, No. 8 ( 2020-08), p. 2322-2331
    Abstract: Expert guidelines specify no upper age limit for alteplase for thrombolysis of acute ischemic stroke (AIS) but, until recently, European regulatory criteria restricted its use to patients aged 18 to 80 years. We performed pooled analyses of randomized controlled trial (RCT) and registry data to evaluate the benefit-risk profile of alteplase for AIS among patients aged 〉 80 years to support a regulatory application to lift the upper age restriction. Methods: Individual patient data were evaluated from 7 randomized trials of alteplase (0.9 mg/kg) versus placebo or open control for AIS, and the European SITS-UTMOST registry database. Clinical outcomes, including good functional outcome (score 0–1, modified Rankin Scale day 90 or Oxford Handicap Score day 180), were evaluated in the full RCT and registry populations, and specified age-based subgroups (≤80 or 〉 80 years) who met existing European regulatory criteria for alteplase, excluding upper age restriction. Results: Regardless of treatment allocation, 90-day mortality was lower among RCT patients aged ≤80 versus 〉 80 years who otherwise met existing European regulatory criteria (246/2405 [10.2%] versus 307/1028 [29.9%] , respectively). Among patients aged 〉 80 years, alteplase versus placebo was associated with a higher proportion of good stroke outcome (modified Rankin Scale score 0–1; 99/518 [19.1%] versus 67/510 [13.1%] ; P =0.0109) and similar 90-day mortality (153/518 [29.5%] versus 154/510 [30.2%] ; P =0.8382). The odds of a good stroke outcome following alteplase allocation in the full RCT population were independent of age ( P =0.7383). Good stroke outcome was reported for almost half (4821/11 169 [43.2%]) of the patients who received alteplase in routine practice. Outcomes in routine practice supported those achieved in RCTs. Conclusions: Alteplase for AIS has a positive benefit-risk profile among patients aged 〉 80 years when administered according to other regulatory criteria. Alteplase for AIS should be evaluated on an individual benefit-risk basis.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/STROKEAHA.119.028396
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
    detail.hit.zdb_id: 1467823-8
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  • 6
    Online Resource
    Online Resource
    Influence of Age on Outcome From Thrombolysis in Acute Stroke : A Controlled Comparison in Patients From the Virtual International Stroke Trials Archive (VISTA)
    Ovid Technologies (Wolters Kluwer Health) ; 2010
    In:  Stroke Vol. 41, No. 12 ( 2010-12), p. 2840-2848
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 41, No. 12 ( 2010-12), p. 2840-2848
    Abstract: Background and Purpose— Thrombolysis for acute ischemic stroke in patients aged 〉 80 years is not approved in some countries due to limited trial data in the very elderly. We compared outcomes between thrombolysed and nonthrombolysed (control) patients from neuroprotection trials to assess any influence of age on response. Method— Among patients with ischemic stroke of known age, pretreatment severity (baseline National Institutes of Health Scale Score), and 90-day outcome (modified Rankin Scale score; National Institutes of Health Scale score), we compared the distribution of modified Rankin score in thrombolysed patients with control subjects by Cochran-Mantel-Haenszel test and then logistic regression after adjustment for age and baseline National Institutes of Health Scale score. We examined patients ≤80 and ≥81 years separately and then each age decile. Results— Rankin data were available for 5817 patients, 1585 thrombolysed and 4232 control subjects; 20.5% were aged 〉 80 years (mean±SD, 85.1±3.4 years). Baseline severity was higher among thrombolysed than control subjects (median National Institutes of Health Scale score 14 versus 13, P 〈 0.05). The distribution of modified Rankin Scale scores was better among thrombolysed patients ( P 〈 0.0001; OR, 1.39; 95% CI, 1.26 to 1.54). The association occurred independently with similar magnitude among young ( P 〈 0.0001; OR, 1.42; 95% CI, 1.26 to 1.59) and elderly ( P =0.002; OR, 1.34; 95% CI, 1.05 to 1.70) patients. ORs were consistent across all age deciles 〉 30 years; outcomes assessed by National Institutes of Health Scale score gave supporting significant findings, and dichotomized modified Rankin Scale score outcomes were also consistent. Conclusions— Outcome after thrombolysis for acute ischemic stroke was significantly better than in control subjects. Despite the expected poorer outcomes among elderly compared with young patients that is independent of any treatment effect, the association between thrombolysis treatment and improved outcome is maintained in the very elderly. Age alone should not be a barrier to treatment.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/STROKEAHA.110.586206
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2010
    detail.hit.zdb_id: 1467823-8
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  • 7
    Online Resource
    Online Resource
    The ECASS 3-Hour Cohort
    S. Karger AG ; 1998
    In:  Cerebrovascular Diseases Vol. 8, No. 4 ( 1998), p. 198-203
    Details
    In: Cerebrovascular Diseases, S. Karger AG, Vol. 8, No. 4 ( 1998), p. 198-203
    Abstract: 〈 b 〉 Objectives: 〈 /b 〉 (1) To determine whether and how outcome measurements in the ECASS trial are influenced by a shorter time window (0–3 vs. 3–6 h) between onset of symptoms and start of thrombolytic therapy using recombinant tissue plasminogen activator (rt-PA) in acute ischemic stroke. (2) To discuss the results of the ECASS 0- to 3-hour cohort with the results of the National Institute of Neurological Disorders and Stroke Study (NINDSS). 〈 b 〉 Design and Analysis: 〈 /b 〉 Analysis of the 0- to 3-hour and the 3- to 6-hour cohort in accordance with the ECASS protocol. Comparative analysis of the ECASS and NINDSS results following the NINDSS protocol using dichotomized endpoints. 〈 b 〉 Main Outcome Measures: 〈 /b 〉 Primary endpoints: modified Rankin Scale, Barthel Index; secondary endpoints: combined Barthel/Rankin, long-term Scandinavian Stroke Scale, National Institutes of Health Stroke Scale, mortality at 30 and 90 days, occurrence of intracranial hemorrhage. NINDS trial endpoint: favorable outcome as defined in the NINDS trial. 〈 b 〉 Results: 〈 /b 〉 In ECASS, 87 patients were randomized within 3 h of stroke onset. Differences in favor of rt-PA treatment can be found for all primary and secondary outcome measures in the ECASS 0- to 3-hour cohort, except for mortality at day 30, which is somewhat higher in the rt-pA-treated group. However, due to the small sample size, the differences do not reach statistical significance. Early infarct signs (as defined by the ECASS protocol) are found as early as 2 h after stroke onset. Parenchymal hemorrhages are found significantly more often among rt-PA-treated patients. The results in the ECASS 0- to 3-hour cohort fit well with the results in NINDSS. 〈 b 〉 Conclusion: 〈 /b 〉 Data from the 3-hour ECASS cohort support the efficacy of early thrombolytic therapy in acute hemispheric stroke patients. Comparing bleeding complications between the ECASS and NINDSS is difficult because of differences in the definition and occurrence of hemorrhagic events.
    Type of Medium: Online Resource
    ISSN: 1015-9770 , 1421-9786
    URL: Article
    DOI: 10.1159/000015851
    Language: English
    Publisher: S. Karger AG
    Publication Date: 1998
    detail.hit.zdb_id: 1482069-9
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  • 8
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    Outcomes of a Pharmacoinvasive Strategy for Successful Versus Failed Fibrinolysis and Primary Percutaneous Intervention in Acute Myocardial Infarction (from the Strategic Reperfusion Early After Myocardial Infarction [STREAM] Study)
    Elsevier BV ; 2014
    In:  The American Journal of Cardiology Vol. 114, No. 6 ( 2014-09), p. 811-819
    Details
    In: The American Journal of Cardiology, Elsevier BV, Vol. 114, No. 6 ( 2014-09), p. 811-819
    Type of Medium: Online Resource
    ISSN: 0002-9149
    URL: Article
    DOI: 10.1016/j.amjcard.2014.06.011
    RVK:
    XA 18500
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 2019595-3
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  • 9
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    A New Nonparametric Approach for Baseline Covariate Adjustment for Two‐Group Comparative Studies
    Wiley ; 2008
    In:  Biometrics Vol. 64, No. 4 ( 2008-12), p. 1110-1116
    Details
    In: Biometrics, Wiley, Vol. 64, No. 4 ( 2008-12), p. 1110-1116
    Abstract: Summary We consider two‐armed clinical trials in which the response and/or the covariates are observed on either a binary, ordinal, or continuous scale. A new general nonparametric (NP) approach for covariate adjustment is presented using the notion of a relative effect to describe treatment effects. The relative effect is defined by the probability of observing a higher response in the experimental than in the control arm. The notion is invariant under monotone transformations of the data and is therefore especially suitable for ordinal data. For a normal or binary distributed response the relative effect is the transformed effect size or the difference of response probability, respectively. An unbiased and consistent NP estimator for the relative effect is presented. Further, we suggest a NP procedure for correcting the relative effect for covariate imbalance and random covariate imbalance, yielding a consistent estimator for the adjusted relative effect. Asymptotic theory has been developed to derive test statistics and confidence intervals. The test statistic is based on the joint behavior of the estimated relative effect for the response and the covariates. It is shown that the test statistic can be used to evaluate the treatment effect in the presence of (random) covariate imbalance. Approximations for small sample sizes are considered as well. The sampling behavior of the estimator of the adjusted relative effect is examined. We also compare the probability of a type I error and the power of our approach to standard covariate adjustment methods by means of a simulation study. Finally, our approach is illustrated on three studies involving ordinal responses and covariates.
    Type of Medium: Online Resource
    ISSN: 0006-341X , 1541-0420
    URL: Issue
    URL: Article
    DOI: 10.1111/biom.2008.64.issue-4
    DOI: 10.1111/j.1541-0420.2008.00994.x
    RVK:
    WA 15000
    Language: English
    Publisher: Wiley
    Publication Date: 2008
    detail.hit.zdb_id: 2054197-1
    SSG: 12
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  • 10
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    Online Resource
    Action limit outlier test: a novel approach for the identification of outliers in bioassay dose–response curves
    Future Science Ltd ; 2020
    In:  Bioanalysis Vol. 12, No. 20 ( 2020-10), p. 1459-1468
    Details
    In: Bioanalysis, Future Science Ltd, Vol. 12, No. 20 ( 2020-10), p. 1459-1468
    Abstract: Aim/Materials & methods: Guidelines like United States Pharmacopeia 1032 [ 1 ] and pharm.Eur. [ 2 ] acknowledge that cell-based bioassays are complex methods and thus prone to outliers. However, investigations into root causes of outliers are often inconclusive. We have established a procedure (including quality control and documentation) implemented in a freely available software application which includes not only the experience of the analyst but also information of historical data. Results: This action limit outlier test is unique to our knowledge. Action limit outlier test allows the determination of outliers efficiently which lead to a significant reduction of false positives in comparison with the traditional outlier test ROUT [ 3 ] or Rosner [ 4 ] alone as shown by our simulated data (58 and 44% reduction of false positives for ROUT and Rosner, respectively).
    Type of Medium: Online Resource
    ISSN: 1757-6180 , 1757-6199
    URL: Article
    DOI: 10.4155/bio-2020-0189
    Language: English
    Publisher: Future Science Ltd
    Publication Date: 2020
    SSG: 15,3
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