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

The prevalence of and factors associated with inclusion of non-English language studies in Campbell systematic reviews: a survey and meta-epidemiological study

BACKGROUND

Studies published in languages other than English are often neglected when research teams conduct systematic reviews. Literature on how to deal with non-English studies when conducting reviews have focused on the importance of including such studies, while less attention has been paid to the practical challenges of locating and assessing relevant non-English studies. We investigated the factors which might predict the inclusion of non-English studies in systematic reviews in the social sciences, to better understand how, when and why these are included/excluded.

METHODS

We appraised all Campbell Collaboration systematic reviews (n = 123) published to July 2016, categorising each by its language inclusiveness. We sought additional information from review authors via a questionnaire and received responses concerning 47 reviews. Data were obtained for 17 factors and we explored correlations with the number of non-English studies in the reviews via statistical regression models. Additionally, we asked authors to identify factors that support or hinder the inclusion of non-English studies.

RESULTS

Of 123 reviews, 108 did not explicitly exclude, and of these, 17 included non-English language studies. One factor correlated with the number of included non-English studies across all models: the number of countries in which the members of the review team work (B-value = 0.56; SE B = 0.24; 95% CI = 0.07-1.03; p = 0.02). This indicates that reviews which included non-English studies were more likely to be produced by international review teams. Our survey showed a dominance of researchers from English-speaking countries (52.9%) and review teams consisting only of team members from these countries (65.9%). The most frequently mentioned challenge to including non-English studies was a lack of resources (funding and time) followed by a lack of language resources (e.g. professional translators).

CONCLUSION

Our findings may indicate a connection between the limited inclusion of non-English studies and a lack of resources, which forces review teams to rely on their limited language skills rather than the support of professional translators. If unaddressed, review teams risk ignoring key data and introduce bias in otherwise high-quality reviews. However, the validity and interpretation of our findings should be further assessed if we are to tackle the challenges of dealing with non-English studies.

Is the coverage of Google Scholar enough to be used alone for systematic reviews

Background

In searches for clinical trials and systematic reviews, it is said that Google Scholar (GS) should never be used in isolation, but in addition to PubMed, Cochrane, and other trusted sources of information. We therefore performed a study to assess the coverage of GS specifically for the studies included in systematic reviews and evaluate if GS was sensitive enough to be used alone for systematic reviews.

Methods

All the original studies included in 29 systematic reviews published in the Cochrane Database Syst Rev or in the JAMA in 2009 were gathered in a gold standard database. GS was searched for all these studies one by one to assess the percentage of studies which could have been identified by searching only GS.

Results

All the 738 original studies included in the gold standard database were retrieved in GS (100%).

Conclusion

The coverage of GS for the studies included in the systematic reviews is 100%. If the authors of the 29 systematic reviews had used only GS, no reference would have been missed. With some improvement in the research options, to increase its precision, GS could become the leading bibliographic database in medicine and could be used alone for systematic reviews.

A quantitative and qualitative evaluation of reports of clinical trials published in six Brazilian dental journals indexed in the Scientific Electronic Library Online (SciELO)

Open access publishing is becoming increasingly popular within the biomedical sciences. SciELO, the Scientific Electronic Library Online, is a digital library covering a selected collection of Brazilian scientific journals many of which provide open access to full-text articles. This library includes a number of dental journals some of which may include reports of clinical trials in English, Portuguese and/or Spanish. Thus, SciELO could play an important role as a source of evidence for dental healthcare interventions especially if it yields a sizeable number of high quality reports.

Frequency of persistent tooth pain after root canal therapy: a systematic review and meta-analysis

INTRODUCTION

Little is known about the frequency of persistent pain after endodontic procedures even though pain is a core patient-oriented outcome. We estimated the frequency of persistent pain, regardless of etiology, after endodontic treatment.

METHODS

Persistent tooth pain was defined as pain present > or = 6 months after endodontic treatment. Endodontic procedures included in the review were pulpectomy, nonsurgical root canal treatment, surgical root canal treatment, and retreatment. Four databases were searched electronically complemented by hand searching. Two independent reviewers determined eligibility, abstracted data, and assessed study quality. A summary estimate of persistent all-cause tooth pain frequency was established by using a random-effects meta-analysis. Using subgroup analyses, we explored the influence of treatment approach (surgical/nonsurgical), longitudinal study design (prospective/retrospective), follow-up rate, follow-up duration, initial treatment versus retreatment, and quality of reporting (Strengthening the Reporting of Observational Studies in Epidemiology rankings) on the pain frequency estimate.

RESULTS

Of 770 articles retrieved and reviewed, 26 met inclusion criteria. A total of 5,777 teeth were enrolled, and 2,996 had follow-up information regarding pain status. We identified 168 teeth with pain and derived a frequency of 5.3% (95% confidence interval, 3.5%-7.2%, p < 0.001) for persistent all-cause tooth pain. High and statistically significant heterogeneity among studies (I2 = 80%) was present. In subgroup analysis, prospective studies had a higher pain frequency (7.6%) than retrospectives studies did (0.9%). Quality of study reporting was identified as the most influential reason for study heterogeneity.

CONCLUSIONS

The frequency of all-cause persistent tooth pain after endodontic procedures was estimated to be 5.3%, with higher report quality studies suggesting >7%.

[Hand searching for controlled clinical trials in German surgical journals. A contribution to evidence-based surgery]

BACKGROUND

The identification of all available and relevant study reports is mandatory for a comprehensive assessment of randomised (RCTs) and controlled clinical trials (CCTs) in systematic reviews. Incomplete compilation of health care journals in electronic databases and incorrect indexing of the studies impair the result of a systematic literature search. An additional search in medical journals that are not listed in electronic databases can obtain higher search precision.

METHODS

In the hand searching project of the Cochrane Collaboration, in Germany 14 surgical journals were searched manually for RCTs and CCTs. The identified study reports were compared with Medline records, and the publication frequency was analysed. The study reports were published in the Cochrane Library and are henceforth available for inclusion in systematic reviews.

RESULTS

Four hundred (77%) of the 519 published volumes in the 14 surgical journals were searched for RCTs and CCTs. Of the 1152 controlled trials (670 RCTs and 482 CCTs) identified, 674 (58%) were not included in Medline.

CONCLUSIONS

The gap between the number of hand search results and the number of Medline indexed RCTs and CCTs is also reflected in other special medical fields. To ensure completeness of the literature compilation, the hand searching project should be continued.

Enhancing access to reports of randomized trials published world-wide--the contribution of EMBASE records to the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library

Background

Randomized trials are essential in assessing the effects of healthcare interventions and are a key component in systematic reviews of effectiveness. Searching for reports of randomized trials in databases is problematic due to the absence of appropriate indexing terms until the 1990s and inconsistent application of these indexing terms thereafter.

Objectives

The objectives of this study are to devise a search strategy for identifying reports of randomized trials in EMBASE which are not already indexed as trials in MEDLINE and to make these reports easily accessible by including them in the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, with the permission of Elsevier, the publishers of EMBASE.

Methods

A highly sensitive search strategy was designed for EMBASE based on free-text and thesaurus terms which occurred frequently in the titles, abstracts, EMTREE terms (or some combination of these) of reports of trials indexed in EMBASE. This search strategy was run against EMBASE from 1980 to 2005 (1974 to 2005 for four of the terms) and records retrieved by the search, which were not already indexed as randomized trials in MEDLINE, were downloaded from EMBASE, printed and read. An analysis of the language of publication was conducted for the reports of trials published in 2005 (the most recent year completed at the time of this study).

Results

Twenty-two search terms were used (including nine which were later rejected due to poor cumulative precision). More than a third of a million records were downloaded and scanned and approximately 80,000 reports of trials were identified which were not already indexed as randomized trials in MEDLINE. These are now easily identifiable in CENTRAL, in The Cochrane Library. Cumulative sensitivity ranged from 0.1% to 60% and cumulative precision ranged from 8% to 61%. The truncated term 'random$' identified 60% of the total number of reports of trials but only 35% of the more than 130,000 records retrieved by this term were reports of trials. The language analysis for the sample year 2005 indicated that of the 18,427 reports indexed as randomized trials in MEDLINE, 959 (5%) were in languages other than English. The EMBASE search identified an additional 658 reports in languages other than English, of which the highest number were in Chinese (320).

Conclusion

The results of the search to date have greatly increased access to reports of trials in EMBASE, especially in some languages other than English. The search strategy used was subjectively derived from a small 'gold standard' set of test records and was not validated in an independent test set. We intend to design an objectively-derived validated search strategy using logistic regression based on the frequency of occurrence of terms in the approximately 80,000 reports of randomized trials identified compared with the frequency of these terms across the entire EMBASE database.

[Randomized controlled and controlled clinical trials in German-language ophthalmological journals]

BACKGROUND

The medical database MEDLINE contains only a part of all published randomized controlled (RCTs) and controlled clinical (CCTs) trials. The validity of a systematic review depends on the complete consideration of all studies pertaining to a clinical question. Therefore, a manual systematic search in medical journals is mandatory.

METHODS

The last 30 years of the three peer-reviewed German-language ophthalmological journals Der Ophthalmologe, Klinische Monatsblätter für Augenheilkunde, and Spektrum der Augenheilkunde were retrospectively searched for controlled trials. All identified RCTs and CCTs were classified according to their ophthalmological subspecialty. The quality of the studies was evaluated using the CONSORT Statement. Moreover, a comparison was made of how many of the studies identified by hand searching are registered in MEDLINE and correctly classified as RCTs/CCTs.

RESULTS

In total 984 RCTs and CCTs were identified; 62% of the trials were from the subspecialty anterior eye segment, 14% belonged to the subspecialty posterior eye segment, and 18% belonged to glaucoma. A sample size calculation was reported in less than 2% of the full-text publications and 34% reported a blinded study design. A randomization process was described in 23% of the RCTs. Most controlled trials were published in the 1990s in all three journals. From 1998 onward, there was a decrease in the number of published controlled trials in the reviewed German literature. About 63% of the studies registered in MEDLINE are correctly classified.

CONCLUSION

In the specialty of ophthalmology there are many important studies which provide basic information for compilation of systematic reviews and clinical guidelines. However, many of the identified clinical trials in German-language journals show deficiencies in the study quality. Only a part of the identified controlled trials are correctly classified in MEDLINE. Therefore, a retrospective registration is essential to complete the electronic database in ophthalmology.

[Systematic reviews and meta-analyses in surgery]

The enormous number of medical publications available online and in print media makes it difficult for surgeons to keep abreast of new scientific developments. In addition to information overload and lack of time, studies of questionable quality and expertise when performing systematic literature searches jeopardize proper surgical decision making. The concept of systematic reviews (SR) and meta-analyses (MA) is based on a critically appraised synthesis of individual trials addressing comparable medical problems. This qualitative evaluation and quantitative aggregation of research findings offer valid decision making tools for the clinician, scientist, and health care authorities. Systematic reviews employ comprehensive methods to control for potential bias when synthesizing individual trials. Thus the clinical question and methodological aspects should be defined a priori in a protocol. In the following step the relevant literature must be identified through systematic searches in databases. After critical assessment of the methodological quality and heterogeneity of individual studies, the results can be presented qualitatively. They also can be quantitatively summarized in MA if appropriate. Compared to single trials, properly conducted SR and MA facilitate more precise estimation of the treatment effect of surgical interventions. Hence they represent an ideal basis for future research endeavors. In conclusion, SR and MA implemented in clinical guidelines, evidence-based consumer information, or health technology assessment, enable the necessary bridging between research and clinical practice.

An evaluation of search and selection methods used in dental systematic reviews published in English

BACKGROUND

Increasing numbers of systematic reviews are published each year, though little has been done to evaluate their search and selection methodology.

METHODS

The authors searched dental systematic reviews published between Jan. 1, 2000, and July 14, 2005, for descriptions of how researchers used multiple electronic databases and secondary searches. They evaluated search and selection methods of identified systematic reviews against the guidelines found in the 2005 Cochrane Handbook for Systematic Reviews of Interventions.

RESULTS

The authors identified 220 unique dental systematic reviews. They found that all aspects of search and selection methodology had improved. In 2005, most systematic reviews documented database names and search dates (90 percent), electronic search terms (95 percent) and inclusion-exclusion criteria (95 percent), and most employed secondary searching (100 percent). Many still failed to search more than MEDLINE (20 percent), document the search strategy (20 percent), use multiple reviewers for selecting studies (25 percent) and include all languages (39 percent).

CONCLUSIONS AND CLINICAL IMPLICATIONS

Systematic review methodology is improving, though key components frequently are absent. Reviews should be read critically and in consideration of the methodological flaws.

Likely country of origin in publications on randomised controlled trials and controlled clinical trials during the last 60 years

BACKGROUND

The number of publications on clinical trials is unknown as well as the countries publishing most trial reports. To try to examine these questions we performed an ecological study.

METHODS

We searched the 454,449 records on publications in The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, Issue 3, 2005 (CD-ROM version) for possible country of origin. We inspected a random sample of 906 records for information on country and type of trial.

RESULTS

There was an exponential growth of publications on randomised controlled trials and controlled clinical trials since 1946, but the growth seems to have seized since 2000. We identified the possible country of origin of 210,974 publications (46.4%). The USA is leading with about 46,789 publications followed by UK, Germany, Italy, the Netherlands, Canada, and France. Sweden becomes the leader with 891 publications per million inhabitants during the last 60 years followed by Denmark (n = 864), New Zealand (n = 791), Finland (n = 781), the Netherlands (n = 570), Switzerland (n = 547), and Norway (n = 543). In depth assessment of the random sample backed these findings.

CONCLUSION

Many records lacked country of origin, even after the additional scrutiny. The number of publications on clinical trials increased exponentially until the turn of the century. Rather small, democratic, and wealthy countries take the lead when the number of publications on clinical trials is calculated based on million inhabitants. If all countries produced the same number of trials as these countries, this could mean thousands of new effective treatments during the next 60 years.

[Randomized and nonrandomized controlled clinical trials in a German surgical journal]

BACKGROUND

Comprehensive identification of relevant literature is mandatory for valid assessment of the effectiveness of surgical interventions. Thus, electronic database searches are often complemented by handsearching of relevant surgical journals. The aim of this study was to assess the quantity and quality of randomized controlled (RCTs) and controlled clinical trials (CCTs) in the German surgical journal Der Chirurg.

METHODS

Quantitative and qualitative assessment was made after handsearching of studies published from 1948 to 2005 in Der Chirurg. Systematic database search (MEDLINE) was used for comparison of RCTs published in Der Chirurg and international surgical journals.

RESULTS

Overall, 112 controlled clinical trials (90 RCTs, 22 CCTs) were identified by handsearching. The implementation of sample size calculation was reported in 12 of 90 (13%) RCTs. Forty-six (51%) did not specify the randomization process, and five (6%) incorporated the "intention to treat" principle in their analyses. After 2000, RCTs were published in declining frequency in Der Chirurg, whereas international surgical journals printed stable quantities of these studies.

CONCLUSION

Improving the prerequisites of patient-centered clinical research in surgery, rigorous implementation of principles of the CONSORT statement, and modified publication strategies may improve the quality and quantity of reports on clinical studies in Germany.

Search and selection methodology of systematic reviews in orthodontics (2000-2004)

INTRODUCTION

More systematic reviews related to orthodontic topics are published each year, although little has been done to evaluate their search and selection methodologies.

METHODS

Systematic reviews related to orthodontics published between January 1, 2000, and December 31, 2004, were searched for their use of multiple electronic databases and secondary searches. The search and selection methods of identified systematic reviews were evaluated against the Cochrane Handbook's guidelines.

RESULTS

Sixteen orthodontic systematic reviews were identified in this period. The percentage of reviews documenting and using each criterion of article searching has changed over the last 5 years, with no recognizable directional trend. On average, most systematic reviews documented their electronic search terms (88%) and inclusion-exclusion criteria (100%), and used secondary searching (75%). Many still failed to search more than MEDLINE (56%), failed to document the database names and search dates (37%), failed to document the search strategy (62%), did not use several reviewers for selecting studies (75%), and did not include all languages (81%).

CONCLUSIONS

The methodology of systematic reviews in orthodontics is still limited, with key methodological components frequently absent or not appropriately described.

Efficacy of stabilization splints for the management of patients with masticatory muscle pain: a qualitative systematic review

This study aimed at providing an answer to two clinical questions related to patients with masticatory muscle pain: 1) Does the use of a full-coverage hard acrylic occlusal appliance (stabilization splint) lead to a significant decrease of symptoms? and 2) Is the treatment success achieved with a stabilization splint more pronounced than the success attained with other forms of treatment (including placebo treatment) or no treatment? A systematic search was carried out in different electronic databases, supplemented by handsearch in four selected dental journals and by examination of the bibliographies of the retrieved articles. Thirteen publications, representing nine controlled clinical studies, could be identified. Reporting quality of most studies as assessed with the Jadad score ranged from 1 to 5. Based on the currently best available evidence it appears that most patients with masticatory muscle pain are helped by the incorporation of a stabilization splint. Nevertheless, evidence is equivocal if improvement of pain symptoms after incorporation of the intraoral appliance is caused by a specific effect of the appliance. A stabilization splint does not appear to yield a better clinical outcome than a soft splint, a non-occluding palatal splint, physical therapy, or body acupuncture. The scarcity of current external evidence emphasizes the need for more and better clinical research.