Full publication of results initially presented in abstracts

BACKGROUND: Abstracts of presentations at scientific meetings are usually available only in conference proceedings. If subsequent full publication of abstract results is based on the magnitude or direction of study results, publication bias may result. Publication bias, in turn, creates problems for those conducting systematic reviews or relying on the published literature for evidence. OBJECTIVES: To determine the rate at which abstract results are subsequently published in full, and the time between meeting presentation and full publication. To assess the association between study characteristics and full publication. SEARCH STRATEGY: We searched MEDLINE, EMBASE, The Cochrane Library, Science Citation Index, reference lists, and author files. Date of most recent search: June 2003. SELECTION CRITERIA: We included all reports that examined the subsequent full publication rate of biomedical results initially presented as abstracts or in summary form. Follow-up of abstracts had to be at least two years. DATA COLLECTION AND ANALYSIS: Two reviewers extracted data. We calculated the weighted mean full publication rate and time to full publication. Dichotomous variables were analyzed using relative risk and random effects models. We assessed time to publication using Kaplan-Meier survival analyses. MAIN RESULTS: Combining data from 79 reports (29,729 abstracts) resulted in a weighted mean full publication rate of 44.5% (95% confidence interval (CI) 43.9 to 45.1). Survival analyses resulted in an estimated publication rate at 9 years of 52.6% for all studies, 63.1% for randomized or controlled clinical trials, and 49.3% for other types of study designs.'Positive' results defined as any 'significant' result showed an association with full publication (RR = 1.30; CI 1.14 to 1.47), as did 'positive' results defined as a result favoring the experimental treatment (RR =1.17; CI 1.02 to 1.35), and 'positive' results emanating from randomized or controlled clinical trials (RR = 1.18, CI 1.07 to 1.30).Other factors associated with full publication include oral presentation (RR = 1.28; CI 1.09 to 1.49); acceptance for meeting presentation (RR = 1.78; CI 1.50 to 2.12); randomized trial study design (RR = 1.24; CI 1.14 to 1.36); and basic research (RR = 0.79; CI 0.70 to 0.89). Higher quality of abstracts describing randomized or controlled clinical trials was also associated with full publication (RR = 1.30, CI 1.00 to 1.71). AUTHORS' CONCLUSIONS: Only 63% of results from abstracts describing randomized or controlled clinical trials are published in full. 'Positive' results were more frequently published than not 'positive' results.

Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results

Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO3 at 950 °C, whereas LOI of pure graphite at 530 °C showed a direct relation to sample size and exposure time, with only 40-70% of the possible weight loss reached after 2 h of exposure and smaller samples losing weight faster than larger ones. Experiments with a standardised lake sediment revealed a strong initial weight loss at 550 °C, but samples continued to lose weight at a slow rate at exposure of up to 64 h, which was likely the effect of loss of volatile salts, structural water of clay minerals or metal oxides, or of inorganic carbon after the initial burning of organic matter. A further test-run revealed that at 550 °C samples in the centre of the furnace lost more weight than marginal samples. At 950 °C this pattern was still apparent but the differences became negligible. Again, LOI was dependent on sample size. An analytical LOI quality control experiment including ten different laboratories was carried out using each laboratory's own LOI procedure as well as a standardised LOI procedure to analyse three different sediments. The range of LOI values between laboratories measured at 550 °C was generally larger when each laboratory used its own method than when using the standard method. This was similar for 950 °C, although the range of values tended to be smaller. The within-laboratory range of LOI measurements for a given sediment was generally small. Comparisons of the results of the individual and the standardised method suggest that there is a laboratory-specific pattern in the results, probably due to differences in laboratory equipment and/or handling that could not be eliminated by standardising the LOI procedure. Factors such as sample size, exposure time, position of samples in the furnace and the laboratory measuring affected LOI results, with LOI at 550 °C being more susceptible to these factors than LOI at 950 °C. We, therefore, recommend analysts to be consistent in the LOI method used in relation to the ignition temperatures, exposure times, and the sample size and to include information on these three parameters when referring to the method.

Source of funding and results of studies of health effects of mobile phone use: systematic review of experimental studies

OBJECTIVES: There is concern regarding the possible health effects of cellular telephone use. We examined whether the source of funding of studies of the effects of low-level radiofrequency radiation is associated with the results of studies. We conducted a systematic review of studies of controlled exposure to radiofrequency radiation with health-related outcomes (electroencephalogram, cognitive or cardiovascular function, hormone levels, symptoms, and subjective well-being). DATA SOURCES: We searched EMBASE, Medline, and a specialist database in February 2005 and scrutinized reference lists from relevant publications. DATA EXTRACTION: Data on the source of funding, study design, methodologic quality, and other study characteristics were extracted. The primary outcome was the reporting of at least one statistically significant association between the exposure and a health-related outcome. Data were analyzed using logistic regression models. DATA SYNTHESIS: Of 59 studies, 12 (20%) were funded exclusively by the telecommunications industry, 11 (19%) were funded by public agencies or charities, 14 (24%) had mixed funding (including industry), and in 22 (37%) the source of funding was not reported. Studies funded exclusively by industry reported the largest number of outcomes, but were least likely to report a statistically significant result: The odds ratio was 0.11 (95% confidence interval, 0.02-0.78), compared with studies funded by public agencies or charities. This finding was not materially altered in analyses adjusted for the number of outcomes reported, study quality, and other factors. CONCLUSIONS: The interpretation of results from studies of health effects of radiofrequency radiation should take sponsorship into account.

Variability of anti-PF4/heparin antibody results obtained by the rapid testing system ID-H/PF4-PaGIA

BACKGROUND: Recent studies have shown that a low clinical pretest probability may be adequate for excluding heparin-induced thrombocytopenia. However, for patients with intermediate or high pretest probability, laboratory testing is essential for confirming or refuting the diagnosis. Rapid assessment of anti-PF4/heparin-antibodies may assist clinical decision-making. OBJECTIVES: To evaluate the performance of rapid ID-H/PF4-PaGIA. In particular, we verified reproducibility of results between plasma and serum specimens, between fresh and frozen samples, and between different ID-H/PF4-polymer lots (polystyrene beads coated with heparin/PF4-complexes). PATIENTS/METHODS: The samples studied were 1376 plasma and 914 corresponding serum samples from patients investigated for suspected heparin-induced thrombocytopenia between January 2000 and October 2008. Anti-PF4/heparin-antibodies were assessed by ID-H/PF4-PaGIA, commercially available ELISAs and heparin-induced platelet aggregation test. RESULTS: Among 914 paired plasma/serum samples we noted discordant results (negative vs. low-titre positive) in nine instances (1%; 95%CI, 0.4-1.6%). Overall, agreement between titres assessed in plasma vs. serum was highly significant (Spearman correlation coefficient, 0.975; P < 0.0001). Forty-seven samples tested both fresh and after freezing/thawing showed a good agreement, with one discordant positive/negative result (Spearman correlation coefficient, 0.970; P < 0.0001). Among 1376 plasma samples we noted a strikingly variable incidence of false negative results (none - 82%; 95%CI, 66-98%), depending on the employed ID-H/PF4-polymer lot. Faulty lots can be recognized by titrating commercial positive controls and stored samples of HIT-patients. CONCLUSION: Laboratories performing the assay should implement stringent internal quality controls in order to recognize potentially faulty ID-H/PF4-polymer lots, thus avoiding false negative results.

Do multiple true-false items beat the commonly used one-best-answers questions regarding to the Ottawa Criteria for Good Assessment? Results of a literature review

Background: Multiple True-False-Items (MTF-Items) might offer some advantages compared to one-best-answer-questions (TypeA) as they allow more than one correct answer and may better represent clinical decisions. However, in medical education assessment MTF-Items are seldom used. Summary of Work: With this literature review existing findings on MTF-items and on TypeA were compared along the Ottawa Criteria for Good Assessment, i.e. (1) reproducibility, (2) feasibility, (3) validity, (4) acceptance, (5) educational effect, (6) catalytic effects, and (7) equivalence. We conducted a literature research on ERIC and Google Scholar including papers from the years 1935 to 2014. We used the search terms “multiple true-false”, “true-false”, “true/false”, and “Kprim” combined with “exam”, “test”, and “assessment”. Summary of Results: We included 29 out of 33 studies. Four of them were carried out in the medical field Compared to TypeA, MTF-Items are associated with (1) higher reproducibility (2) lower feasibility (3) similar validity (4) higher acceptance (5) higher educational effect (6) no studies on catalytic effects or (7) equivalence. Discussion and Conclusions: While studies show overall good characteristics of MTF items according to the Ottawa criteria, this type of question seems to be rather seldom used. One reason might be the reported lower feasibility. Overall the literature base is still weak. Furthermore, only 14 % of literature is from the medical domain. Further studies to better understand the characteristics of MTF-Items in the medical domain are warranted. Take-home messages: Overall the literature base is weak and therefore further studies are needed. Existing studies show that: MTF-Items show higher reliability, acceptance and educational effect; MTF-Items are more difficult to produce

Endovascular treatment of popliteal artery aneurysms: a single-center experience

PURPOSE: To evaluate the use of covered stent-grafts in the endovascular treatment (ET) of popliteal artery aneurysms (PAAs). MATERIALS AND METHODS: A retrospective analysis was conducted over a period of 52 months in 18 consecutive patients (17 men; mean age +/- SD, 70 years +/- 11) undergoing ET of PAAs with the Viabahn endograft in a single center. Patient symptoms, aneurysm characteristics, technical outcomes, complications, and follow-up were assessed. RESULTS: Aneurysm diameters ranged from 12 to 51 mm with a mean of 30 mm (+/-11). Thirteen aneurysms (72.2%) were partially thrombosed and 12 patients (66.6%) had symptoms of lower limb ischemia at presentation (11 chronic and one acute). The technical success rate was 94%. Intraprocedural emboli and endoleak occurred in one and two patients, respectively. Fourteen patients were available for follow-up after successful treatment, with a mean follow-up time of 15 months (range, 7-37 months). All stent-grafts were patent after 1 month, with no mortality or limb loss. The primary patency rate with complete exclusion of the aneurysm at 6 months was 86%. Pre- and postprocedural noninvasive arterial studies were available in 10 patients, demonstrating improvement of the ankle-brachial index from 0.96 +/- 0.41 to 1.17 +/- 0.18, respectively (P = .06). CONCLUSIONS: Endovascular stent-graft repair of PAAs is a feasible treatment option. However, further follow-up studies regarding the durability of results are required.

Assessment of a new Goldmann applanation tonometer

The classic Goldmann applanation tonometer (GAT) has been further developed by Haag-Streit International. The applanation principle has been retained, while the internal force transmission and the pressure gauging have been optimised, the display of results digitised. The authors compared the GAT standard with the new GAT digital.

A simple tool for stereological assessment of digital images: the STEPanizer

STEPanizer is an easy-to-use computer-based software tool for the stereological assessment of digitally captured images from all kinds of microscopical (LM, TEM, LSM) and macroscopical (radiology, tomography) imaging modalities. The program design focuses on providing the user a defined workflow adapted to most basic stereological tasks. The software is compact, that is user friendly without being bulky. STEPanizer comprises the creation of test systems, the appropriate display of digital images with superimposed test systems, a scaling facility, a counting module and an export function for the transfer of results to spreadsheet programs. Here we describe the major workflow of the tool illustrating the application on two examples from transmission electron microscopy and light microscopy, respectively.

[Prophylaxis and therapy of postdural puncture headache--a critical evaluation of treatment options]

Since the first description of spinal and epidural anaesthesia, postdural puncture headache (PDPH) is a well known complication. Its prophylaxis and treatment has been studied and discussed for more than 100 years, but the evidence is still limited. Due to relatively low prevalence of PDPH, prospective RCTs are often missing, and the frequently self-limiting character of PDPH impedes an adequate interpretation of results from studies without a control group. Taking side effects and complications into account, a prophylactic treatment of PDPH cannot be recommended. In case of PDPH, non-opioid analgesics are the first choice treatment. The epidural blood patch remains the mainstay of severe PDPH therapy. Noninvasive therapies like theophylline, sumatriptan and ACTH can be an alternative. However, an evidence-based recommendation is lacking. The development of standard operating procedures for accidental dural punctures and PDPH is recommended.

Uses and misuses of the STROBE statement: bibliographic study

Objectives Appropriate reporting is central to the application of findings from research to clinical practice. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations consist of a checklist of 22 items that provide guidance on the reporting of cohort, case-control and cross-sectional studies, in order to facilitate critical appraisal and interpretation of results. STROBE was published in October 2007 in several journals including The Lancet, BMJ, Annals of Internal Medicine and PLoS Medicine. Within the framework of the revision of the STROBE recommendations, the authors examined the context and circumstances in which the STROBE statement was used in the past. Design The authors searched the Web of Science database in August 2010 for articles which cited STROBE and examined a random sample of 100 articles using a standardised, piloted data extraction form. The use of STROBE in observational studies and systematic reviews (including meta-analyses) was classified as appropriate or inappropriate. The use of STROBE to guide the reporting of observational studies was considered appropriate. Inappropriate uses included the use of STROBE as a tool to assess the methodological quality of studies or as a guideline on how to design and conduct studies. Results The authors identified 640 articles that cited STROBE. In the random sample of 100 articles, about half were observational studies (32%) or systematic reviews (19%). Comments, editorials and letters accounted for 15%, methodological articles for 8%, and recommendations and narrative reviews for 26% of articles. Of the 32 observational studies, 26 (81%) made appropriate use of STROBE, and three uses (10%) were considered inappropriate. Among 19 systematic reviews, 10 (53%) used STROBE inappropriately as a tool to assess study quality. Conclusions The STROBE reporting recommendations are frequently used inappropriately in systematic reviews and meta-analyses as an instrument to assess the methodological quality of observational studies.

'New perspectives on well-known issues': patients' experiences and perceptions of safety in Swiss hospitals

Patients' reports of safety-related events and perceptions of safety can be a valuable source for hospitals. Patients of eight acute care hospitals in Switzerland were surveyed for safety-related events and concerns for safety. In workshops with hospitals areas for improvement were analyzed and priorities for change identified. To evaluate the benefit of the approach, semi-structured interviews were conducted with hospital risk managers. 3,983 patients returned the survey (55% response rate). 21.4% reported at least one definite safety event, and the mean number of 'definite' incidents per patient was 0.31 (95% CI=0.29 to 0.34). 3.2% were very concerned and 14.7% were somewhat concerned about medical errors and safety. Having experienced a safety-related event, younger age, length of stay, poor health and a poor education increased the probability of reporting concerns. With some exceptions, results confirmed the hospitals' a priori expectations regarding the strengths and weaknesses of their institutions. Risk managers emphasized the usability of results for their work and the special value of referring to the patient's perspective at their home institutions. A considerable fraction of patients subjectively experiences safety-related events and is concerned about safety. Patient-generated data introduced a new quality into the discussion of safety issues within hospitals, and some expected that patients' experiences and concerns could affect patient volumes. Though the study is limited by the short time horizon and the lack of follow-up, the results suggest that the described approach is feasible and can serve as a supplemental tool for risk identification and management.

Reporting Experiments in Homeopathic Basic Research—Description of the Checklist Development

The objective of this study was to develop a criteria catalogue serving as a guideline for authors to improve quality of reporting experiments in basic research in homeopathy. A Delphi Process was initiated including three rounds of adjusting and phrasing plus two consensus conferences. European researchers who published experimental work within the last 5 years were involved. A checklist for authors provide a catalogue with 23 criteria. The “Introduction” should focus on underlying hypotheses, the homeopathic principle investigated and state if experiments are exploratory or confirmatory. “Materials and methods” should comprise information on object of investigation, experimental setup, parameters, intervention and statistical methods. A more detailed description on the homeopathic substances, for example, manufacture, dilution method, starting point of dilution is required. A further result of the Delphi process is to raise scientists' awareness of reporting blinding, allocation, replication, quality control and system performance controls. The part “Results” should provide the exact number of treated units per setting which were included in each analysis and state missing samples and drop outs. Results presented in tables and figures are as important as appropriate measures of effect size, uncertainty and probability. “Discussion” in a report should depict more than a general interpretation of results in the context of current evidence but also limitations and an appraisal of aptitude for the chosen experimental model. Authors of homeopathic basic research publications are encouraged to apply our checklist when preparing their manuscripts. Feedback is encouraged on applicability, strength and limitations of the list to enable future revisions.

Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain

We present results from the international field campaign DAURE (Detn. of the sources of atm. Aerosols in Urban and Rural Environments in the Western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during Feb.-March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) anal. for elemental and org. carbon (EC and OC) and source apportionment for these data. We combine the results with those from component anal. of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based ests. of biomass burning OC, source apportionment of filter data with inorg. compn. + EC + OC, submicron bulk potassium (K) concns., and gaseous acetonitrile concns. At BCN, 87 % and 91 % of the EC on av., in winter and summer, resp., had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to org. carbon (OC) at BCN was 40 % and 48 %, in winter and summer, resp., and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ∼47 % primary whereas at MSY the fossil OC is mainly secondary (∼85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorol. transport conditions. The estd. biogenic secondary OC at MSY only increased by ∼40 % compared to the order-of-magnitude increase obsd. for biogenic volatile org. compds. (VOCs) between winter and summer, which highlights the uncertainties in the estn. of that component. Biomass burning contributions estd. using the 14C technique ranged from similar to slightly higher than when estd. using other techniques, and the different estns. were highly or moderately correlated. Differences can be explained by the contribution of secondary org. matter (not included in the primary biomass burning source ests.), and/or by an over-estn. of the biomass burning OC contribution by the 14C technique if the estd. biomass burning EC/OC ratio used for the calcns. is too high for this region. Acetonitrile concns. correlate well with the biomass burning EC detd. by 14C. K is a noisy tracer for biomass burning. [on SciFinder(R)]