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Gerd Antes

Publications and source records attributed to Gerd Antes.

At least 19 recordsLinked to original sources
PubMed2007

A test for publication bias in meta-analysis with sparse binary data.

A new test for the detection of publication bias in meta-analysis with sparse binary data is proposed. The test statistic is based on observed and expected cell frequencies, and the variance of the observed cell frequencies. These quantities are utilized in a rank correlation test. Type I error rate and power of the test are evaluated in simulations; results are compared to those of two other commonly used test procedures. Sample sizes were generated according to findings in a survey of eight German medical journals. Simulation results indicate that, in contrast to existing test procedures, the new test holds the prescribed significance level when data are sparse. However, the power of all tests is low in many situations of practical importance.

Anemia↗
PubMed2006

The demise of the randomised controlled trial: bibliometric study of the German-language health care literature, 1948 to 2004.

BACKGROUND: In order to reduce systematic errors (such as language bias) and increase the precision of the summary treatment effect estimate, a comprehensive identification of randomised controlled trials (RCT), irrespective of publication language, is crucial in systematic reviews and meta-analyses. We identified trials in the German general health care literature. METHODS: Eight German language general health care journals were searched for randomised controlled trials and analysed with respect to the number of published RCTs each year and the size of trials. RESULTS: A total of 1618 trials were identified with a median total number of 43 patients per trial. Between 1970 and 2004 a small but constant rise in sample size from a median number of 30 to 60 patients per trial can be observed. The number of published trials was very low between 1948 and 1970, but increased between 1970 and 1986 to a maximum of 11.2 RCTs per journal and year. In the following time period a striking decline of the number of RCTs was observed. Between 1999 and 2001 only 0.8 RCTs per journal and year were published, in the next three years, the number of published trials increased to 1.7 RCTs per journal and year. CONCLUSION: German language general health care journals no longer have a role in the dissemination of trial results. The slight rise in the number of published RCTs in the last three years can be explained by a change of publication language from German to English of three of the analysed journals.

Bibliometrics↗
PubMed2006

[How much evidence is needed in the case of fatal diseases and when?].

Spectacular cases of healing of usually fatal diseases gain much attention and put pressure on physicians to apply treatments which have not been sufficiently approved in clinical studies. But often these cases are poorly documented. Also, the number of spontaneous remissions in cancer is greatly overestimated. Promising individual observations must be confirmed by case series in order to collect information which can help future patients. Efforts are necessary to organize well planned studies, especially on rare diseases.

Attitude to Death↗
PubMed2005

Treatment of ocular hypertension and open angle glaucoma: meta-analysis of randomised controlled trials.

OBJECTIVE: Open angle glaucoma is one of the most common causes of blindness in industrialised nations. Treatments to lower ocular pressure are widely used in glaucoma prevention and treatment, despite conflicting evidence. DESIGN: We performed meta-analyses to reassess the effectiveness of pressure lowering treatment to delay the development of glaucoma in ocular hypertension, as well as progression of manifest open angle glaucoma. DATA SOURCES: Medline, Embase, and the Cochrane Library. SELECTION OF STUDIES: Eligible studies were randomised controlled trials with a concurrent untreated control group and information on time to glaucomatous changes to visual field and optic disc. Trial reports were reviewed independently by two investigators in an unblinded standardised manner. RESULTS: Meta-analysis of trials in ocular hypertension showed a significant preventive effect of reducing intraocular pressure on progression to glaucoma (hazard ratio 0.56, 95% confidence interval 0.39 to 0.81, P = 0.01; number needed to treat 12). Pooled data of studies in manifest glaucoma showed a significant delay of visual field deterioration (0.65, 0.49 to 0.87, P = 0.003; NNT = 7), with subgroup analysis showing a larger effect in patients with raised pressure and a reduced effect in normal tension glaucoma (subgroup comparison: not significant). CONCLUSIONS: Lowering intraocular pressure in patients with ocular hypertension or manifest glaucoma is beneficial in reducing the risk of visual field loss in the long term.

Glaucoma, Open-Angle↗
PubMed2004

Does disinfection of environmental surfaces influence nosocomial infection rates? A systematic review.

OBJECTIVE: To review the evidence on the effects of disinfection of environmental surfaces in hospitals (as compared with cleaning without use of disinfectants) on the occurrence of nosocomial infections. METHODS: Systematic review of experimental and nonexperimental intervention studies dealing with environmental disinfection or cleaning in different health care settings. RESULTS: A total of 236 scientific articles were identified. None described a meta-analysis, systematic review, or randomized controlled trial. Only 4 articles described completed cohort studies matching the inclusion criteria. None of these studies showed lower infection rates associated with routine disinfection of surfaces (mainly floors) versus cleaning with detergent only. CONCLUSIONS: Disinfectants may pose a danger to staff, patients, and the environment and require special safety precautions. However, targeted disinfection of certain environmental surfaces is in certain instances an established component of hospital infection control. Given the complex, multifactorial nature of nosocomial infections, well-designed studies that systematically investigate the role of surface disinfection are required.

Cross Infection↗
PubMed2004

[German language articles on controlled trials in oral and maxillofacial surgery].

Various authors have shown that only a part of all reports of randomized controlled trials (RCTs) and controlled clinical trials (CCTs) are accessible in Medline. However, the validity of systematic reviews and meta-analyses heavily depends on the completeness of the identified studies published for a particular clinical problem. Therefore, an additional manual search in dental/medical journals is often indispensable. The major purpose of the present article was to identify all published reports of RCTs and CCTs dealing with topics covered by the discipline oral and maxillofacial surgery. The journals Deutsche Zahnärztliche Zeitschrift, Schwetzer Monatsschrift für Zahnmedizin, Mund-, Kiefer- und Gesichtschirurgie, Stomatologie, and Stomatologie der DDR were manually searched. The publication type of the identified clinical trial reports was determined and compared with Medline. Among the 14,860 articles perused, 202 RCTs and 396 CCTs were identified. 74 RCTs (36.6%) and 104 CCTs (26.2%) referred to topics related to oral and maxillofacial surgery. Of the 74 RCT reports, 44 are included in Medline, and 14 are indexed with the correct publication type term. The majority of RCTs were carried out in the field of oral and maxillofacial surgery. Unfortunately, only a part of German-language reports of dental clinical trials are accessible in Medline. Therefore, a literature search restricted to this database is likely to be incomplete, possibly leading to biased results.

Abstracting and Indexing↗
PubMed2004

[The evidence base of clinical practice guidelines, health technology assessments and patient information as a basis for clinical decision-making].

Valid assessments of benefit and harm of health care interventions are derived from unbiased patient-based clinical trials. Bias sources may affect different study types in different ways, leading to varying validity of study results. The efficient transfer of relevant study results into medical practice is the main objective of evidence-based medicine. To archive this, systematic reviews summarising the study results with respect to a focussed question have proved a powerful tool. They can be used for decision making by individuals as well as evidence source for clinical practice guidelines, health technology assessment and patient information.

Clinical Trials as Topic↗
PubMed2002

Inflation of type I error rate in two statistical tests for the detection of publication bias in meta-analyses with binary outcomes.

The use of meta-analysis to combine results of several trials is still increasing in the medical field. The validity of a meta-analysis may be affected by various sources of bias (for example, publication bias, language bias). Therefore, an analysis of bias should be an integral part of any systematic review. Statistical tests and graphical methods have been developed for this purpose. In this paper, two statistical tests for the detection of bias in meta-analysis were investigated in a simulation study. Binary outcome data, which are very common in medical applications, were considered and relative effect measures (odds ratios, relative risk) were used for pooling. Sample sizes were generated according to findings in a survey of eight German medical journals. Simulation results indicate an inflation of type I error rates for both tests when the data are sparse. Results get worse with increasing treatment effect and number of trials combined. Valid statistical tests for the detection of bias in meta-analysis with sparse data need to be developed.

Computer Simulation↗
PubMed2002

Nearly half of dental randomized controlled trials published in German are not included in Medline.

Randomized controlled trials (RCTs) are considered the most reliable type of clinical intervention studies. However, not all reports of RCTs are accessible in Medline. This can impede the validity of the results of systematic reviews. Ten German-language dental journals were manually searched to locate reports of controlled clinical trials published between 1970 and 2000. The publication type was determined and compared with Medline. Of the 15 777 articles, 210 reports of RCTs and 410 articles of non-randomized controlled clinical trials (CCTs) were identified. Only 56% of the RCTs and 75% of the CCTs are available in Medline. Of the 118 reports of RCTs registered in Medline. 15 are indexed with the correct Publication Type term. Our data suggest that (a) hand-searching plays a valuable role in identifying reports of clinical dental trials, and (b) a literature search in Medline is likely to yield incomplete results.

Dental Research↗
PubMed2002

The contribution of handsearching European general health care journals to the Cochrane Controlled Trials Register.

A fundamental aim of any systematic review is that all relevant studies should be identified and considered for inclusion. Limitations with searching bibliographic databases led the Cochrane Collaboration to search journals by hand for reports of trials. This article presents the results of a 3-year project to identify and make accessible reports of randomized trials published in European general health care journals. Overall, 21,620 reports of controlled trials were identified from 119 journals from 16 countries. More than three quarters (76%) were published in U.K. or German journals. Only 3,640 (17%) reports were indexed in MEDLINE as controlled trials, and 6,554 (30%) were not indexed in MEDLINE at all. Bibliographic details for all reports are available by searching The Cochrane Controlled Trials Register in The Cochrane Library. This project has ensured that a large proportion of trial reports not previously identifiable has been made accessible to those preparing systematic reviews.

Abstracting and Indexing↗