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1.  Detecting, quantifying and adjusting for publication bias in meta-analyses: protocol of a systematic review on methods 
Systematic Reviews  2013;2:60.
Background
Health professionals and policymakers aspire to make healthcare decisions based on the entire relevant research evidence. This, however, can rarely be achieved because a considerable amount of research findings are not published, especially in case of ‘negative’ results - a phenomenon widely recognized as publication bias. Different methods of detecting, quantifying and adjusting for publication bias in meta-analyses have been described in the literature, such as graphical approaches and formal statistical tests to detect publication bias, and statistical approaches to modify effect sizes to adjust a pooled estimate when the presence of publication bias is suspected. An up-to-date systematic review of the existing methods is lacking.
Methods/design
The objectives of this systematic review are as follows:
• To systematically review methodological articles which focus on non-publication of studies and to describe methods of detecting and/or quantifying and/or adjusting for publication bias in meta-analyses.
• To appraise strengths and weaknesses of methods, the resources they require, and the conditions under which the method could be used, based on findings of included studies.
We will systematically search Web of Science, Medline, and the Cochrane Library for methodological articles that describe at least one method of detecting and/or quantifying and/or adjusting for publication bias in meta-analyses. A dedicated data extraction form is developed and pilot-tested. Working in teams of two, we will independently extract relevant information from each eligible article. As this will be a qualitative systematic review, data reporting will involve a descriptive summary.
Discussion
Results are expected to be publicly available in mid 2013. This systematic review together with the results of other systematic reviews of the OPEN project (To Overcome Failure to Publish Negative Findings) will serve as a basis for the development of future policies and guidelines regarding the assessment and handling of publication bias in meta-analyses.
doi:10.1186/2046-4053-2-60
PMCID: PMC3733739  PMID: 23885765
Publication bias; Full publication; Underreporting; Detecting; Quantifying; The OPEN project
2.  Defining publication bias: protocol for a systematic review of highly cited articles and proposal for a new framework 
Systematic Reviews  2013;2:34.
Background
Selective publication of studies, which is commonly called publication bias, is widely recognized. Over the years a new nomenclature for other types of bias related to non-publication or distortion related to the dissemination of research findings has been developed. However, several of these different biases are often still summarized by the term 'publication bias'.
Methods/Design
As part of the OPEN Project (To Overcome failure to Publish nEgative fiNdings) we will conduct a systematic review with the following objectives:
- To systematically review highly cited articles that focus on non-publication of studies and to present the various definitions of biases related to the dissemination of research findings contained in the articles identified.
- To develop and discuss a new framework on nomenclature of various aspects of distortion in the dissemination process that leads to public availability of research findings in an international group of experts in the context of the OPEN Project.
We will systematically search Web of Knowledge for highly cited articles that provide a definition of biases related to the dissemination of research findings. A specifically designed data extraction form will be developed and pilot-tested. Working in teams of two, we will independently extract relevant information from each eligible article.
For the development of a new framework we will construct an initial table listing different levels and different hazards en route to making research findings public. An international group of experts will iteratively review the table and reflect on its content until no new insights emerge and consensus has been reached.
Discussion
Results are expected to be publicly available in mid-2013. This systematic review together with the results of other systematic reviews of the OPEN project will serve as a basis for the development of future policies and guidelines regarding the assessment and prevention of publication bias.
doi:10.1186/2046-4053-2-34
PMCID: PMC3667005  PMID: 23692820
Publication bias; Full publication; Underreporting; New framework; The OPEN project
3.  Early versus deferred androgen suppression therapy for patients with lymph node-positive prostate cancer after local therapy with curative intent: a systematic review 
BMC Cancer  2013;13:131.
Background
There is currently no consensus regarding the optimal timing for androgen suppression therapy in patients with prostate cancer that have undergone local therapy with curative intent but are proven to have node-positive disease without signs of distant metastases at the time of local therapy. The objective of this systematic review was to determine the benefits and harms of early (at the time of local therapy) versus deferred (at the time of clinical disease progression) androgen suppression therapy for patients with node-positive prostate cancer after local therapy.
Methods
The protocol was registered prospectively (CRD42011001221; http://www.crd.york.ac.uk/PROSPERO). We searched the MEDLINE, EMBASE, and CENTRAL databases, as well as reference lists, the abstracts of three major conferences, and three trial registers, to identify randomized controlled trials (search update 04/08/2012). Two authors independently screened the identified articles, assessed trial quality, and extracted data.
Results
Four studies including 398 patients were identified for inclusion. Early androgen suppression therapy lead to a significant decrease in overall mortality (HR 0.62, 95% CI 0.46-0.84), cancer-specific mortality (HR 0.34, 95% CI 0.18-0.64), and clinical progression at 3 or 9 years (RR 0.29, 95% CI 0.16-0.52 at 3 years and RR 0.49, 95% CI 0.36-0.67 at 9 years). One study showed an increase of adverse effects with early androgen suppression therapy. All trials had substantial methodological limitations.
Conclusions
The data available suggest an improvement in survival and delayed disease progression but increased adverse events for patients with node-positive prostate cancer after local therapy treated with early androgen suppression therapy versus deferred androgen suppression therapy. However, quality of data is low. Randomized controlled trials with blinding of outcome assessment, planned to determine the timing of androgen suppression therapy in node-positive prostate cancer using modern diagnostic imaging modalities, biochemical testing, and standardized follow-up schedules should be conducted to confirm these findings.
doi:10.1186/1471-2407-13-131
PMCID: PMC3621662  PMID: 23510155
Prostatic neoplasms; Lymphatic metastasis; Lymph node excision; Androgen suppression therapy; Systematic review; Meta-analysis
4.  All Nations Depend on the Global Knowledge Pool – Analysis of Country of Origin of Studies Used for Health Technology Assessments in Germany 
PLoS ONE  2013;8(3):e59213.
Background
Health Technology Assessments (HTAs) are used to inform decision-making and their usefulness depends on the quality and relevance of research and specific studies for health-policy decisions. Little is known about the country of origin of studies used for HTAs.
Objective
To investigate which countries have made the largest contributions to inform health policy decisions through studies included in HTAs in Germany.
Methods
The country of origin was extracted from all studies included in HTAs of the German Institute for Quality and Efficiency in Health Care, (IQWiG), published from 2/2006 to 9/2010. Studies were ranked according to the total number of studies per country, adjusted for population size, gross domestic product (GDP), and total health expenditure.
Results
1087 studies were included in 54 HTA reports. Studies were assigned to 45 countries. Most of the studies (27%) originated from the United States (USA), 18% were multinational, followed by 7% from the United Kingdom (UK) and 5% from Germany. Nordic countries led the ranking when adjusting for population size/million (ranks 1-3,6,9/45 countries), GDP/billion US$ (1,2,5,9,14/45), or health expenditure/billion US$ (1,3,5,12,13/45). The relative contribution of the UK was stable in the analyses when adjusted for population size (7/45), GDP (7/45), and health expenditure (9/45), whereas the USA (13, 18, and 30/45) and Germany (17, 19, and 21/45) dropped in the ranking.
Conclusions
More than half of the studies relevant for evidence-informed decision-making in Germany originated from the USA, followed by multinational research and the UK. Only 5% of the studies originated from Germany. According to our findings, there appears to be some discrepancy between the use of globally generated evidence and the contribution to the knowledge pool by individual countries.
doi:10.1371/journal.pone.0059213
PMCID: PMC3597619  PMID: 23516611
5.  Correction: Scientific Value of Systematic Reviews: Survey of Editors of Core Clinical Journals 
PLoS ONE  2012;7(10):10.1371/annotation/b9a9cb87-3d96-47e4-a073-a7e97a19f47c.
doi:10.1371/annotation/b9a9cb87-3d96-47e4-a073-a7e97a19f47c
PMCID: PMC3476878
6.  Tamoxifen for the management of breast events induced by non-steroidal antiandrogens in patients with prostate cancer: a systematic review 
BMC Medicine  2012;10:96.
Background
Tamoxifen has emerged as a potential management option for gynecomastia and breast pain due to non-steroidal antiandrogens, and it is considered an alternative to surgery or radiotherapy. The objective of this systematic review was to assess the benefits and harms of tamoxifen, in comparison to other treatment options, for either the prophylaxis or treatment of breast events induced by non-steroidal antiandrogens in prostate cancer patients.
Methods
We searched CENTRAL, MEDLINE, EMBASE, reference lists, the abstracts of three major conferences and three trial registers to identify ongoing randomized controlled trials (RCTs). Two authors independently screened the articles identified, assessed the trial quality and extracted data. The protocol was prospectively registered (CRD42011001320; http://www.crd.york.ac.uk/PROSPERO).
Results
Four studies were identified. Tamoxifen significantly reduced the risk of suffering from gynecomastia (risk ratio 9RR0 0.10, 95% CI 0.05 to 0.22) or breast pain (RR 0.06, 95% CI 0.02 to 0.17) at six months compared to untreated controls. Tamoxifen also showed a significant benefit for the prevention of gynecomastia (RR 0.22, 95% CI 0.08 to 0.58) and breast pain (RR 0.25, 95% CI 0.10 to 0.64) when compared to anastrozole after a median of 12 months. One study showed a significant benefit of tamoxifen for the prevention of gynecomastia (RR 0.24, 95% CI 0.09 to 0.65) and breast pain (RR 0.20, 95% CI 0.06 to 0.65) when compared with radiotherapy at six months. Radiotherapy increased the risk of suffering from nipple erythema and skin irritation, but there were no significant differences for any other adverse events (all P > 0.05).
Conclusions
The currently available evidence suggests good efficacy of tamoxifen for the prevention and treatment of breast events induced by non-steroidal antiandrogens. The impact of tamoxifen therapy on long-term adverse events, disease progression and survival remains unclear. Further large, well-designed RCTs, including long-term follow-ups, are warranted. Also, the optimal dose needs to be clarified.
doi:10.1186/1741-7015-10-96
PMCID: PMC3464149  PMID: 22925442
Prostatic neoplasms; Androgen suppression therapy; Gynecomastia; Tamoxifen; Systematic review; Meta-analysis
7.  A Safety Review and Meta-Analyses of Bevacizumab and Ranibizumab: Off-Label versus Goldstandard 
PLoS ONE  2012;7(8):e42701.
Background
We set out a systemic review to evaluate whether off-label bevacizumab is as safe as licensed ranibizumab, and whether bevacizumab can be justifiably offered to patients as a treatment for age-related macular degeneration with robust evidence of no differential risk.
Methods and Findings
Medline, Embase and the Cochrane Library were searched with no limitations of language and year of publication. We included RCTs with a minimum follow-up of one year which investigated bevacizumab or ranibizumab in direct comparison or against any other control group (indirect comparison). Direct comparison (3 trials, 1333 patients): The one year data show a significantly higher rate of ocular adverse effects (AE) with bevacizumab compared to ranibizumab (RR = 2.8; 95% CI 1.2–6.5). The proportion of patients with serious infections and gastrointestinal disorders was also higher with bevacizumab than with ranibizumab (RR = 1.3; 95% CI 1.0–1.7). Arterial thromboembolic events were equally distributed among the groups. Indirect comparison: Ranibizumab versus any control (5 trials, 4054 patients): The two year results of three landmark trials showed that while absolute rates of serious ocular AE were low (≤2.1%), relative harm was significantly raised (RR = 3.1; 95% CI 1.1–8.9). A significant increase in nonocular haemorrhage was also observed with ranibizumab (RR = 1.7; 95% CI 1.1–2.7). Bevacizumab versus any control (3 trials, 244 patients): We were unable to judge the safety profile of bevacizumab due to the poor quality of AE monitoring and reporting in the trials.
Conclusions
Evidence from head-to-head trials raises concern about an increased risk of ocular and multiple systemic AE with bevacizumab. Therefore, clinicians and patients should continue to carefully weight up the benefits and harms when choosing between the two treatment options. We also emphasize the need for studies that are powered not just for efficacy, but for defined safety outcomes based on the signals detected in this systematic review.
doi:10.1371/journal.pone.0042701
PMCID: PMC3411814  PMID: 22880086
8.  Scientific Value of Systematic Reviews: Survey of Editors of Core Clinical Journals 
PLoS ONE  2012;7(5):e35732.
Background
Synthesizing research evidence using systematic and rigorous methods has become a key feature of evidence-based medicine and knowledge translation. Systematic reviews (SRs) may or may not include a meta-analysis depending on the suitability of available data. They are often being criticised as ‘secondary research’ and denied the status of original research. Scientific journals play an important role in the publication process. How they appraise a given type of research influences the status of that research in the scientific community. We investigated the attitudes of editors of core clinical journals towards SRs and their value for publication.
Methods
We identified the 118 journals labelled as “core clinical journals” by the National Library of Medicine, USA in April 2009. The journals’ editors were surveyed by email in 2009 and asked whether they considered SRs as original research projects; whether they published SRs; and for which section of the journal they would consider a SR manuscript.
Results
The editors of 65 journals (55%) responded. Most respondents considered SRs to be original research (71%) and almost all journals (93%) published SRs. Several editors regarded the use of Cochrane methodology or a meta-analysis as quality criteria; for some respondents these criteria were premises for the consideration of SRs as original research. Journals placed SRs in various sections such as “Review” or “Feature article”. Characterization of non-responding journals showed that about two thirds do publish systematic reviews.
Discussion
Currently, the editors of most core clinical journals consider SRs original research. Our findings are limited by a non-responder rate of 45%. Individual comments suggest that this is a grey area and attitudes differ widely. A debate about the definition of ‘original research’ in the context of SRs is warranted.
doi:10.1371/journal.pone.0035732
PMCID: PMC3341385  PMID: 22563469
9.  Evidence-based medicine and Web 2.0: friend or foe? 
doi:10.3399/bjgp11X567342
PMCID: PMC3063037  PMID: 21439203
10.  Do urology journals enforce trial registration? A cross-sectional study of published trials 
BMJ Open  2011;1(2):e000430.
Objectives
(1) To assess endorsement of trial registration in author instructions of urology-related journals and (2) to assess whether randomised controlled trials (RCTs) in the field of urology were effectively registered.
Design
Cross-sectional study of author instructions and published trials.
Setting
Journals publishing in the field of urology.
Participants
First, the authors analysed author instructions of 55 urology-related journals indexed in ‘Journal Citation Reports 2009’ (12/2010). The authors divided these journals in two groups: those requiring and those not mentioning trial registration as a precondition for publication. Second, the authors chose the five journals with the highest impact factor (IF) from each group.
Intervention
MEDLINE search to identify RCTs published in these 10 journals in 2009 (01/2011); search of the clinical trials meta-search interface of WHO (International Clinical Trials Registry Platform) for RCTs that lacked information about registration (01–03/2011). Two authors independently assessed the information.
Outcome measures
Proportion of journals providing advice about trial registration and proportion of trials registered.
Results
Of 55 journals analysed, 26 (47.3%) provided some editorial advice about trial registration. Journals with higher IFs were more likely to mention trial registration explicitly (p=0.015). Of 106 RCTs published in 2009, 63 were registered (59.4%) with a tendency to an increase after 2005 (83.3%, p=0.035). 71.4% (30/42) of the RCTs that were published in journals mentioning and requiring registration, and 51.6% (33/64) of the RCTs that were published in journals that did not mention trial registration explicitly were registered. This difference was statistically significant (p=0.04).
Conclusions
The existence of a statement about trial registration in author instructions resulted in a higher proportion of registered RCTs in those journals. Journals with higher IFs were more likely to mention trial registration.
Article summary
Article focus
Trial registration can increase scientific transparency, but its implementation in specialty fields such as urology is unclear.
To assess the endorsement of trial registration in the author instructions of urology-related journals.
To assess whether randomised controlled trials in the field were effectively registered.
Key messages
A statement of trial registration in author instructions resulted in a higher proportion of registered randomised controlled trials.
Journals with high impact factors were more likely to mention trial registration.
We suggest, though, that ensuring trial registration is not the responsibility only of the editors. Medical scientists should realise that trial registration is necessary to contribute to transparency in research.
Strength and limitations of this study
Two authors independently assessed information regarding editorial advice about trial registration and identified the randomised controlled trials.
Potential bias occurred if registered randomised controlled trials were reported without giving a registration number and we could not identify them in the meta-search interface of WHO (International Clinical Trials Registry Platform).
Results might not be representative of the uro-nephrological field as a whole and reported figures may overestimate compliance with trial registration.
doi:10.1136/bmjopen-2011-000430
PMCID: PMC3236819  PMID: 22146890
11.  Treatment of depressive disorders in primary care - protocol of a multiple treatment systematic review of randomized controlled trials 
BMC Family Practice  2011;12:127.
Background
Several systematic reviews have summarized the evidence for specific treatments of primary care patients suffering from depression. However, it is not possible to answer the question how the available treatment options compare with each other as review methods differ. We aim to systematically review and compare the available evidence for the effectiveness of pharmacological, psychological, and combined treatments for patients with depressive disorders in primary care.
Methods/Design
To be included, studies have to be randomized trials comparing antidepressant medication (tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), hypericum extracts, other agents) and/or psychological therapies (e.g. interpersonal psychotherapy, cognitive therapy, behavioural therapy, short dynamically-oriented psychotherapy) with another active therapy, placebo or sham intervention, routine care or no treatment in primary care patients in the acute phase of a depressive episode. Main outcome measure is response after completion of acute phase treatment. Eligible studies will be identified from available systematic reviews, from searches in electronic databases (Medline, Embase and Central), trial registers, and citation tracking. Two reviewers will independently extract study data and assess the risk of bias using the Cochrane Collaboration's corresponding tool. Meta-analyses (random effects model, inverse variance weighting) will be performed for direct comparisons of single interventions and for groups of similar interventions (e.g. SSRIs vs. tricyclics) and defined time-windows (up to 3 months and above). If possible, a global analysis of the relative effectiveness of treatments will be estimated from all available direct and indirect evidence that is present in a network of treatments and comparisons.
Discussion
Practitioners do not only want to know whether there is evidence that a specific treatment is more effective than placebo, but also how the treatment options compare to each other. Therefore, we believe that a multiple treatment systematic review of primary-care based randomized controlled trials on the most important therapies against depression is timely.
doi:10.1186/1471-2296-12-127
PMCID: PMC3226438  PMID: 22085705
12.  Distribution of Country of Origin in Studies Used in Cochrane Reviews 
PLoS ONE  2011;6(4):e18798.
Background and Objective
Inclusion in systematic reviews is one important component in judging the potential impact of clinical studies upon practice and hence the ‘value for money’ of spending for clinical research. This study aims to quantify the distribution of countries of origin of clinical studies used in Cochrane Reviews (CRs), and to link these data to the size of a country and to its spending on research.
Methods
Random sample of publications used for CRs published in Issue 1 2008 and of publications used in CRs in the field of complementary and alternative medicine (CAM). Publications without original data were excluded. Likely countries of origin determined based on abstracts/full texts. CIA World Factbook (population data) and OECD database (economic data) were used.
Results
1,000 random entries out of 140,005 references available in all specialities. In 876 (91.4%) of 959 eligible studies, country of origin was determined. The USA was the leading contributor (36.0% of the studies), followed by UK (13.4%), Canada (5.3%), Australia and Sweden (3.7%). In the CAM sample, country of origin was determined in 458 (93.5%) of 497 assessed studies. Again, the USA was the leading contributor (24.9%), with China also emerging as a significant contributor (24.7%) in this field. For both samples, the contribution of smaller countries (especially Scandinavian countries, Greece, and Ireland) became more noteworthy when considered in relation to population size and research spending.
Conclusions
Our results support the leading roles of both the USA and the UK in publishing clinical papers. The emerging role of China can be seen, particularly related to CAM studies. Taking into account size of population and economic power, countries like France, Germany, Italy, and Spain provide small contributions. In contrast, smaller countries like Australia, Denmark, Finland, Ireland, New Zealand, and Sweden also play major roles.
doi:10.1371/journal.pone.0018798
PMCID: PMC3079732  PMID: 21526195
13.  Are pediatric Open Access journals promoting good publication practice? An analysis of author instructions 
BMC Pediatrics  2011;11:27.
Background
Several studies analyzed whether conventional journals in general medicine or specialties such as pediatrics endorse recommendations aiming to improve publication practice. Despite evidence showing benefits of these recommendations, the proportion of endorsing journals has been moderate to low and varied considerably for different recommendations. About half of pediatric journals indexed in the Journal Citation Report referred to the Uniform Requirements for Manuscripts of the International Committee of Medical Journal Editors (ICMJE) but only about a quarter recommended registration of trials. We aimed to investigate to what extent pediatric open-access (OA) journals endorse these recommendations. We hypothesized that a high proportion of these journals have adopted recommendations on good publication practice since OA electronic publishing has been associated with a number of editorial innovations aiming at improved access and transparency.
Methods
We identified 41 journals publishing original research in the subject category "Health Sciences, Medicine (General), Pediatrics" of the Directory of Open Access Journals http://www.doaj.org. From the journals' online author instructions we extracted information regarding endorsement of four domains of editorial policy: the Uniform Requirements for Manuscripts, trial registration, disclosure of conflicts of interest and five major reporting guidelines such as the CONSORT (Consolidated Standards of Reporting Trials) statement. Two investigators collected data independently.
Results
The Uniform Requirements were mentioned by 27 (66%) pediatric OA journals. Thirteen (32%) required or recommended trial registration prior to publication of a trial report. Conflict of interest policies were stated by 25 journals (61%). Advice about reporting guidelines was less frequent: CONSORT was referred to by 12 journals (29%) followed by other reporting guidelines (MOOSE, PRISMA or STARD) (8 journals, 20%) and STROBE (3 journals, 7%). The EQUATOR network, a platform of several guideline initiatives, was acknowledged by 4 journals (10%).
Journals published by OA publishing houses gave more guidance than journals published by professional societies or other publishers.
Conclusions
Pediatric OA journals mentioned certain recommendations such as the Uniform Requirements or trial registration more frequently than conventional journals; however, endorsement is still only moderate. Further research should confirm these exploratory findings in other medical fields and should clarify what the motivations and barriers are in implementing such policies.
doi:10.1186/1471-2431-11-27
PMCID: PMC3084157  PMID: 21477335
14.  Reporting of eligibility criteria of randomised trials: cohort study comparing trial protocols with subsequent articles 
Objective To determine whether and how eligibility criteria of participants prespecified in protocols of randomised trials are reported in subsequent articles.
Design Cohort study.
Setting Protocols submitted to the ethics committee of a German medical faculty.
Data sources 52 trial protocols and 78 subsequent publications published between 2000 and 2006.
Main outcome measure Proportion of matching, missing, modified, or newly added eligibility criteria between trial protocols and subsequent publications.
Results Differences were found between protocols and subsequent publications for all 52 trials. Information on eligibility criteria was missing in the publications for all 52 trials (100%, 95% confidence interval 93% to 100%), modified for 44 (85%, 72% to 93%), and newly added for 21 (41%, 27% to 55%). The mean number of eligibility criteria for each trial was 25 (range 7-43) and the mean proportion of matching eligibility criteria per trial was 50% (95% confidence interval 44% to 55%, range 13-93). Of 1248 eligibility criteria prespecified in the protocols, 606 (49%, 46% to 51%) were matching in subsequent publications, 479 (38%, 36% to 41%) were missing, and 163 (13%, 11% to 15%) were modified. 51 eligibility criteria were added to publications. Most prespecified eligibility criteria were about comorbidity (42%, 39% to 45%), treatment (20%, 18% to 22%), or type or severity of illness (17%, 15% to 19%). Most of the missing eligibility criteria (96%, 94% to 97%) and modified eligibility criteria (54%, 46% to 62%) suggested broader study populations and most of the added eligibility criteria (86%, 74% to 94%) suggested narrower study populations.
Conclusions Many users of trial information rely on published journal articles. These articles generally do not reflect the exact definition of the study population as prespecified in the protocol. Incomplete or inadequate reporting of eligibility criteria hampers a proper assessment of the applicability of trial results.
doi:10.1136/bmj.d1828
PMCID: PMC3071036  PMID: 21467104
15.  Effectiveness of screening preschool children for amblyopia: a systematic review 
BMC Ophthalmology  2009;9:3.
Background
Amblyopia and amblyogenic factors like strabismus and refractive errors are the most common vision disorders in children. Although different studies suggest that preschool vision screening is associated with a reduced prevalence rate of amblyopia, the value of these programmes is the subject of a continuing scientific and health policy discussion. Therefore, this systematic review focuses on the question of whether screening for amblyopia in children up to the age of six years leads to better vision outcomes.
Methods
Ten bibliographic databases were searched for randomised controlled trials, non-randomised controlled trials and cohort studies with no limitations to a specific year of publication and language. The searches were supplemented by handsearching the bibliographies of included studies and reviews to identify articles not captured through our main search strategy.
Results
Five studies met the inclusion criteria. Of these, three studies suggested that screening is associated with an absolute reduction in the prevalence of amblyopia between 0.9% and 1.6% (relative reduction: between 45% and 62%). However, the studies showed weaknesses, limiting the validity and reliability of their findings. The main limitation was that studies with significant results considered only a proportion of the originally recruited children in their analysis. On the other hand, retrospective sample size calculation indicated that the power based on the cohort size was not sufficient to detect small changes between the groups. Outcome parameters such as quality of life or adverse effects of screening have not been adequately investigated in the literature currently available.
Conclusion
Population based preschool vision screening programmes cannot be sufficiently assessed by the literature currently available. However, it is most likely that the present systematic review contains the most detailed description of the main limitations in current available literature evaluating these programmes. Therefore, future research work should be guided by the findings of this publication.
doi:10.1186/1471-2415-9-3
PMCID: PMC2731050  PMID: 19607693
16.  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.
doi:10.1186/1471-2288-6-30
PMCID: PMC1533847  PMID: 16824217
17.  Treatment of ocular hypertension and open angle glaucoma: meta-analysis of randomised controlled trials 
BMJ : British Medical Journal  2005;331(7509):134.
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.
doi:10.1136/bmj.38506.594977.E0
PMCID: PMC558697  PMID: 15994659

Results 1-18 (18)