Time filter

Source Type

Pieper D.,Witten/Herdecke University | Buechter R.B.,Institute for Quality and Efficiency in Health Care IQWiG | Li L.,Lanzhou University | Prediger B.,Witten/Herdecke University | Eikermann M.,Witten/Herdecke University
Journal of Clinical Epidemiology | Year: 2015

Objectives To summarize all available evidence on measurement properties in terms of reliability, validity, and feasibility of the Assessment of Multiple Systematic Reviews (AMSTAR) tool, including R(evised)-AMSTAR. Study Design and Setting MEDLINE, EMBASE, Psycinfo, and CINAHL were searched for studies containing information on measurement properties of the tools in October 2013. We extracted data on study characteristics and measurement properties. These data were analyzed following measurement criteria. Results We included 13 studies, four of them were labeled as validation studies. Nine articles dealt with AMSTAR, two articles dealt with R-AMSTAR, and one article dealt with both instruments. In terms of interrater reliability, most items showed a substantial agreement (>0.6). The median intraclass correlation coefficient (ICC) for the overall score of AMSTAR was 0.83 (range 0.60-0.98), indicating a high agreement. In terms of validity, ICCs were very high with all but one ICC lower than 0.8 when the AMSTAR score was compared with scores from other tools. Scoring AMSTAR takes between 10 and 20 minutes. Conclusion AMSTAR seems to be reliable and valid. Further investigations for systematic reviews of other study designs than randomized controlled trials are needed. R-AMSTAR should be further investigated as evidence for its use is limited and its measurement properties have not been studied sufficiently. In general, test-retest reliability should be investigated in future studies. © 2015 Elsevier Inc. All rights reserved.

Pieper D.,Witten/Herdecke University | Buechter R.,Institute for Quality and Efficiency in Health Care IQWiG | Jerinic P.,Witten/Herdecke University | Eikermann M.,Witten/Herdecke University
Journal of Clinical Epidemiology | Year: 2012

Objective: To examine published overviews of systematic reviews in terms of descriptive and methodological characteristics. Study Design and Setting: MEDLINE, Database of Abstracts of Reviews of Effects, the Cochrane Database of Systematic Reviews, and several Health Technology Assessment databases were searched for overviews of reviews up to February 2012. We extracted data from the methods and results sections of the included overviews. These data were analyzed descriptively as frequencies or medians and interquartile ranges. Results: We included 126 overviews of reviews. According to our sample, publication rates for overviews have risen in the last decade. The quality of the included reviews was systematically appraised in 64% of the overviews. The most commonly used assessment tools were the Overview Quality Assessment Questionnaire (26%), Assessment of Multiple Systematic Reviews (11%), and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (5%). Only three of 18 overviews restricted to Cochrane reviews in our sample performed a quality assessment. Strategies to deal with discordant reviews were reported in 5% of the overviews. Searches for additional primary studies were conducted in 5% of the overviews. Conclusion: Overviews of reviews often lack methodological rigor. Methodological standards and reporting guidelines for overviews are needed to improve the quality of this new publication type. © 2012 Elsevier Inc. All rights reserved.

Bender R.,Institute for Quality and Efficiency in Health Care IQWiG | Bender R.,University of Cologne | Vervolgyi V.,Institute for Quality and Efficiency in Health Care IQWiG
Contemporary Clinical Trials | Year: 2010

The number needed to treat (NNT) is a popular measure to describe the absolute effect of a new treatment compared with a standard treatment or placebo in randomised controlled trials (RCTs) with binary outcome. For applications in epidemiology, the average risk difference (ARD) approach based upon logistic regression was proposed to estimate NNT measures with adjustment for covariates. In the context of cohort studies, averaging is performed separately over the unexposed and the exposed persons to account for possible different exposure effects in the two groups or over the entire sample. In this paper, we apply the ARD approach to estimate adjusted NNTs in RCT settings with balanced covariates where it is adequate to average over the whole sample. It is known that the consequence of adjusting for balanced covariates in logistic regression is on one hand a loss of precision and on the other hand an increased efficiency in testing for treatment effects. However, these results are based upon the investigation of regression coefficients and corresponding odds ratios. By means of simulations we show that the estimation of risk differences and NNTs with adjustment for balanced covariates leads to a gain in precision. A considerable gain in precision is obtained in the case of strong covariate predictors with large variance. Therefore, it is preferable to adjust for balanced covariates in RCTs when the treatment effect is expressed in terms of risk differences and NNTs and the covariate represents a strong predictor. © 2010 Elsevier Inc.

Brockhaus A.C.,Institute for Quality and Efficiency in Health Care IQWiG | Brockhaus A.C.,University of Cologne | Bender R.,Institute for Quality and Efficiency in Health Care IQWiG | Skipka G.,Institute for Quality and Efficiency in Health Care IQWiG
Statistics in Medicine | Year: 2014

Meta-analysis has generally been accepted as a fundamental tool for combining effect estimates from several studies. For binary studies with rare events, the Peto odds ratio (POR) method has become the relative effect estimator of choice. However, the POR leads to biased estimates for the OR when treatment effects are large or the group size ratio is not balanced. The aim of this work is to derive the limit of the POR estimator for increasing sample size, to investigate whether the POR limit is equal to the true OR and, if this is not the case, in which situations the POR limit is sufficiently close to the OR. It was found that the derived limit of the expected POR is not equivalent to the OR, because it depends on the group size ratio. Thus, the POR represents a different effect measure. We investigated in which situations the POR is reasonably close to the OR and found that this depends only slightly on the baseline risk within the range (0.001; 0.1) yet substantially on the group size ratio and the effect size itself. We derived the maximum effect size of the POR for different group size ratios and tolerated amounts of bias, for which the POR method results in an acceptable estimator of the OR. We conclude that the limit of the expected POR can be regarded as a new effect measure, which can be used in the presented situations as a valid estimate of the true OR. © 2014 John Wiley & Sons, Ltd.

Laubendera R.P.,Ludwig Maximilians University of Munich | Bender R.,Institute for Quality and Efficiency in Health Care IQWiG | Bender R.,University of Cologne
Statistics in Medicine | Year: 2010

In medical research, risk difference (RD) and number needed to treat (NNT) measures for survival times have been mainly proposed without consideration of covariates. In this paper, we develop adjusted RD and NNT measures for use in observational studies with survival time outcomes within the framework of the Cox proportional hazards regression model taking the distribution of confounders into account. We consider the typical situation of a cohort study in which the effect of an exposure on a survival time outcome is investigated and important covariates have to be taken into account. The exposure effect described by means of the RD and NNT measures in dependence on whether the effect of allocating an exposure to unexposed persons (number needed to be exposed) or that of removing an exposure from exposed persons (exposure impact number) is considered. Estimation of these adjusted RD and NNT measures is performed by using the average RD approach recently developed for logistic regression. To determine standard errors and confidence intervals for these estimators we use two approaches, the delta method with respect to the regression coefficients of the Cox model and bootstrapping and compare each other. The performance of these estimators is assessed by performing Monte Carlo simulations demonstrating clear advantages of the bootstrap method. The proposed method for point and interval estimation of adjusted RD and NNT measures in the Cox model is illustrated by means of data of the Düsseldorf Obesity Mortality Study (DOMS). Copyright © 2010 John Wiley & Sons, Ltd.

Hausner E.,Institute for Quality and Efficiency in Health Care IQWiG | Guddat C.,Institute for Quality and Efficiency in Health Care | Hermanns T.,Institute for Quality and Efficiency in Health Care IQWiG | Lampert U.,Institute for Quality and Efficiency in Health Care IQWiG | Waffenschmidt S.,Institute for Quality and Efficiency in Health Care IQWiG
Journal of Clinical Epidemiology | Year: 2015

Background Different approaches can be adopted for the development of search strategies of systematic reviews. The objective approach draws on already established text analysis methods for developing search filters. Our aim was to determine whether the objective approach for the development of search strategies was noninferior to the conceptual approach commonly used in Cochrane reviews (CRs). Methods We conducted a search for CRs published in the Cochrane Library. The studies included in the CRs were searched for in MEDLINE and represented the total set. We then tested whether references previously removed could be identified via the objective approach. We also reconstructed the original search strategies from the CRs to determine why references could not be identified by the objective approach. As we performed the validation of the search strategies without study filters, we used only sensitivity as a quality measure and did not calculate precision. Results The objective approach yielded a mean sensitivity of 96% based on 13 searches. The noninferiority test showed that this approach was noninferior to the conceptual approach used in the CRs (P < 0.002). An additional descriptive analysis showed that the original MEDLINE strategies could identify only 86% of all references; however, this lower sensitivity was largely due to one CR. Conclusion To the best of our knowledge, our findings indicate for the first time that the objective approach for the development of search strategies is noninferior to the conceptual approach. © 2015 The Authors.

Vervolgyi E.,Institute for Quality and Efficiency in Health Care IQWiG
BMC medical research methodology | Year: 2011

To assess the reporting of loss to follow-up (LTFU) information in articles on randomised controlled trials (RCTs) with time-to-event outcomes, and to assess whether discrepancies affect the validity of study results. Literature survey of all issues of the BMJ, Lancet, JAMA, and New England Journal of Medicine published between 2003 and 2005. Eligible articles were reports of RCTs including at least one Kaplan-Meier plot. Articles were classified as "assessable" if sufficient information was available to assess LTFU. In these articles, LTFU information was derived from Kaplan-Meier plots, extracted from the text, and compared. Articles were then classified as "consistent" or "not consistent". Sensitivity analyses were performed to assess the validity of study results. 319 eligible articles were identified. 187 (59%) were classified as "assessable", as they included sufficient information for evaluation; 140 of 319 (44%) presented consistent LTFU information between the Kaplan-Meier plot and text. 47 of 319 (15%) were classified as "not consistent". These 47 articles were included in sensitivity analyses. When various imputation methods were used, the results of a chi2-test applied to the corresponding 2 × 2 table changed and hence were not robust in about half of the studies. Less than half of the articles on RCTs using Kaplan-Meier plots provide assessable and consistent LTFU information, thus questioning the validity of the results and conclusions of many studies presenting survival analyses. Authors should improve the presentation of both Kaplan-Meier plots and LTFU information, and reviewers of study publications and journal editors should critically appraise the validity of the information provided.

Buechter R.B.,Institute for Quality and Efficiency in Health Care IQWiG
German medical science : GMS e-journal | Year: 2011

To summarize the best available evidence on effectiveness of therapeutic or sport climbing in preventing or treating health problems. We searched Medline, Embase, CENTRAL, PsycINFO, PEDro, OTseeker and SportDiscus for randomized controlled trials published up to December 26, 2010. We included all trials assessing patient-relevant outcomes. Two reviewers independently selected relevant studies, assessed their methodological quality and extracted data. Quality of evidence was rated using the GRADE system. Data were entered into RevMan 5 to calculate effect sizes and 95% confidence intervals where appropriate. Eligible for inclusion were four RCTs studying the effectiveness of climbing in (a) geriatric patients, (b) adults with multiple sclerosis, (c) adults with chronic low-back pain and (d) children with disabilities and poor motor function. The sample sizes ranged between 20 and 95. All trials had major methodological limitations. We found very low quality evidence that therapeutic climbing may improve activities of daily living in geriatric patients compared to physiotherapy as measured by the Barthel index (difference in mean change score: 2.32 [95%-CI: 0.45 to 4.19]). We found very low quality evidence that therapeutic climbing compared to standard exercise therapy may improve physical functioning (difference in mean change score: 16.15 [95%-CI: 4.45 to 27.85]) and general physical health (13.14 [95%-CI: 3.61 to 22.67]) as measured by the SF-36 in adults with chronic low back-pain. Evidence for the effectiveness of therapeutic climbing is limited to small trials at high risk of bias. The effects of therapeutic climbing are therefore unclear.

Sauerland S.,Institute for Quality and Efficiency in Health Care IQWiG
Cochrane database of systematic reviews (Online) | Year: 2011

There are many different techniques currently in use for ventral and incisional hernia repair. Laparoscopic techniques have become more common in recent years, although the evidence is sparse. We compared laparoscopic with open repair in patients with (primary) ventral or incisional hernia. We searched the following electronic databases: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, metaRegister of Controlled Trials. The last searches were conducted in July 2010. In addition, congress abstracts were searched by hand. We selected randomised controlled studies (RCTs), which compared the two techniques in patients with ventral or incisional hernia. Studies were included irrespective of language, publication status, or sample size. We did not include quasi-randomised trials. Two authors assessed trial quality and extracted data independently. Meta-analytic results are expressed as relative risks (RR) or weighted mean difference (WMD). We included 10 RCTs with a total number of 880 patients suffering primarily from primary ventral or incisional hernia. No trials were identified on umbilical or parastomal hernia. The recurrence rate was not different between laparoscopic and open surgery (RR 1.22; 95% CI 0.62 to 2.38; I(2) = 0%), but patients were followed up for less than two years in half of the trials. Results on operative time were too heterogeneous to be pooled. The risk of intraoperative enterotomy was slightly higher in laparoscopic hernia repair (Peto OR 2.33; 95% CI 0.53 to 10.35), but this result stems from only 7 cases with bowel lesion (5 vs. 2). The most clear and consistent result was that laparoscopic surgery reduced the risk of wound infection (RR = 0.26; 95% CI 0.15 to 0.46; I(2)= 0%). Laparoscopic surgery shortened hospital stay significantly in 6 out of 9 trials, but again data were heterogeneous. Based on a small number of trials, it was not possible to detect any difference in pain intensity, both in the short- and long-term evaluation. Laparoscopic repair apparently led to much higher in-hospital costs. The short-term results of laparoscopic repair in ventral hernia are promising. In spite of the risks of adhesiolysis, the technique is safe. Nevertheless, long-term follow-up is needed in order to elucidate whether laparoscopic repair of ventral/incisional hernia is efficacious.

Droste S.,Institute for Quality and Efficiency in Health Care IQWiG | Dintsios C.-M.,Institute for Quality and Efficiency in Health Care IQWiG | Gerber A.,Institute for Quality and Efficiency in Health Care IQWiG
International Journal of Technology Assessment in Health Care | Year: 2010

Background: Comprehensive health technology assessments (HTAs) include thorough reflections on ethical issues associated with health technologies, their use, and value-based decisions in the assessment process. As methods of information retrieval for effectiveness assessments are not applicable to information retrieval on ethical issues, a specific methodological approach is necessary. Objectives: In the absence of existing adapted methods, our objective was to develop a methodological approach for the systematic retrieval of information on ethical issues related to health technologies. Method and Results: A literature search was conducted to verify the non-existence of published comprehensive methodological approaches for the information retrieval on ethical issues for HTAs, and resulted in no hits. We, therefore, developed a step-by-step workflow following the workflow of information retrieval for effectiveness assessments: Step 1: Translation of the search question using the PICO scheme and additional components. Step 2: Concept building by modeling and linking search components. Step 3: Identification of synonyms in all relevant languages. Step 4: Selection of relevant information sources. Step 5: Design of search strategies for bibliographic databases. Step 6: Execution of search strategies and information seeking, including hand-searching. Step 7: Saving of retrieval results and standardized reporting of the process and results. Step 8: Final quality check and calculation of precision and recall. Conclusions: Systematic searching for information on ethical issues related to health technologies can be performed following the common retrieval workflow for effectiveness assessments, but should be performed separately applying adapted procedures and search terms on ethical issues relevant to the research question. Copyright © Cambridge University Press 2010.

Loading Institute for Quality and Efficiency in Health Care IQWiG collaborators
Loading Institute for Quality and Efficiency in Health Care IQWiG collaborators