92 research outputs found
Are methodological quality and completeness of reporting associated with citation-based measures of publication impact? A secondary analysis of a systematic review of dementia biomarker studies
Objective: To determine whether methodological and reporting quality are associated with surrogate measures of publication impact in the field of dementia biomarker studies.
Methods: We assessed dementia biomarker studies included in a previous systematic review in terms of methodological and reporting quality using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) and Standards for Reporting of Diagnostic Accuracy (STARD), respectively. We extracted additional study and journal-related data from each publication to account for factors shown to be associated with impact in previous research. We explored associations between potential determinants and measures of publication impact in univariable and stepwise multivariable linear regression analyses.
Outcome measures: We aimed to collect data on four measures of publication impact: two traditional measuresāaverage number of citations per year and 5-year impact factor of the publishing journal and two alternative measuresāthe Altmetric Attention Score and counts of electronic downloads.
Results: The systematic review included 142 studies. Due to limited data, Altmetric Attention Scores and electronic downloads were excluded from the analysis, leaving traditional metrics as the only analysed outcome measures. We found no relationship between QUADAS and traditional metrics. Citation rates were independently associated with 5-year journal impact factor (Ī²=0.42; p<0.001), journal subject area (Ī²=0.39; p<0.001), number of years since publication (Ī²=-0.29; p<0.001) and STARD (Ī²=0.13; p<0.05). Independent determinants of 5-year journal impact factor were citation rates (Ī²=0.45; p<0.001), statement on conflict of interest (Ī²=0.22; p<0.01) and baseline sample size (Ī²=0.15; p<0.05).
Conclusions: Citation rates and 5-year journal impact factor appear to measure different dimensions of impact. Citation rates were weakly associated with completeness of reporting, while neither traditional metric was related to methodological rigour. Our results suggest that high publication usage and journal outlet is not a guarantee of quality and readers should critically appraise all papers regardless of presumed impact
Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for the early diagnosis of dementia across a variety of healthcare settings
This is a protocol for a Cochrane Review (Diagnostic test accuracy). The objectives are as follows:
To determine the diagnostic accuracy of the informant based questionnaire IQCODE in a population free from dementia for the delayed diagnosis of dementia
Machine learning reduced workload with minimal risk of missing studies: development and evaluation of an RCT classifier for Cochrane Reviews
BACKGROUND:
To describe the development, calibration and evaluation of a machine learning classifier designed to
reduce study identification workload in Cochrane for producing systematic reviews.
METHODS:
A machine learning classifier for retrieving RCTs was developed (the āCochrane RCT Classifierā), with
the algorithm trained using a dataset of title-abstract records from Embase, manually labelled by the
Cochrane Crowd. The classifier was then calibrated using a further dataset of similar records
manually labelled by the Clinical Hedges team, aiming for 99% recall. Finally, the recall of the
calibrated classifier was evaluated using records of RCTs included in Cochrane Reviews that had
abstracts of sufficient length to allow machine classification.
RESULTS:
The Cochrane RCT Classifier was trained using 280,620 records (20,454 of which reported RCTs). A
classification threshold was set using 49,025 calibration records (1,587 of which reported RCTs) and
our bootstrap validation found the classifier had recall of 0.99 (95% CI 0.98 to 0.99) and precision of
0.08 (95% CI 0.06 to 0.12) in this dataset. The final, calibrated RCT classifier correctly retrieved
43,783 (99.5%) of 44,007 RCTs included in Cochrane Reviews but missed 224 (0.5%). Older records
were more likely to be missed than those more recently published.
CONCLUSIONS:
The Cochrane RCT Classifier can reduce manual study identification workload for Cochrane reviews,
with a very low and acceptable risk of missing eligible RCTs. This classifier now forms part of the
Evidence Pipeline, an integrated workflow deployed within Cochrane to help improve the efficiency
of the study identification processes that support systematic review production
Cost-effectiveness of noninvasive liver fibrosis tests for treatment decisions in patients with chronic hepatitis C
The cost-effectiveness of noninvasive tests (NITs) as alternatives to liver biopsy is unknown. We compared the cost-effectiveness of using NITs to inform treatment decisions in adult patients with chronic hepatitis C (CHC). We conducted a systematic review and meta-analysis to calculate the diagnostic accuracy of various NITs using a bivariate random-effects model. We constructed a probabilistic decision analytical model to estimate health care costs and outcomes (quality-adjusted life-years; QALYs) using data from the meta-analysis, literature, and national UK data. We compared the cost-effectiveness of four treatment strategies: testing with NITs and treating patients with fibrosis stage ā„F2; testing with liver biopsy and treating patients with ā„F2; treat none; and treat all irrespective of fibrosis. We compared all NITs and tested the cost-effectiveness using current triple therapy with boceprevir or telaprevir, but also modeled new, more-potent antivirals. Treating all patients without any previous NIT was the most effective strategy and had an incremental cost-effectiveness ratio (ICER) of Ā£9,204 per additional QALY gained. The exploratory analysis of currently licensed sofosbuvir treatment regimens found that treat all was cost-effective, compared to using an NIT to decide on treatment, with an ICER of Ā£16,028 per QALY gained. The exploratory analysis to assess the possible effect on results of new treatments, found that if SVR rates increased to >90% for genotypes 1-4, the incremental treatment cost threshold for the "treat all" strategy to remain the most cost-effective strategy would be Ā£37,500. Above this threshold, the most cost-effective option would be noninvasive testing with magnetic resonance elastography (ICER=Ā£9,189). Conclusions: Treating all adult patients with CHC, irrespective of fibrosis stage, is the most cost-effective strategy with currently available drugs in developed countries. Ā© 2014 The Authors
Infrared Diagnostics for the Extended 12 micron Sample of Seyferts
We present an analysis of Spitzer IRS spectroscopy of 83 active galaxies from
the extended 12 micron sample. We find rank correlations between several
tracers of star formation which suggest that (1) the PAH feature is a reliable
tracer of star formation, (2) there is a significant contribution to the
heating of the cool dust by stars, (3) the H emission is also primarily
excited by star formation. The 55-90 vs. 20-30 spectral index plot is also a
diagnostic of the relative contribution of Starburst to AGN. We see there is a
large change in spectral index across the sample. Thus, the contribution to the
IR spectrum from the AGN and starburst components can be comparable in
magnitude but the relative contribution also varies widely across the sample.
We find rank correlations between several AGN tracers. We search for
correlations between AGN and Starburst tracers and we conclude that the AGN and
Starburst tracers are not correlated. This is consistent with our conclusion
that the relative strength of the AGN and Starburst components varies widely
across the sample. Thus, there is no simple link between AGN fueling and Black
Hole Growth and star formation in these galaxies. The distribution of Sil 10
micron and 18 micron strengths is consistent with the clumpy torus models of
Sirocky et al. We find a rank correlation between the [NeV] 14 micron line and
the 6.7 micron continuum which may be due to an extended component of hot dust.
The Sy 2s with a Hidden Broad Line Region (HBLR) have a higher ratio of AGN to
Starburst contribution to the SED than Sy 2s without an HBLR. This may
contribute to the detection of the HBLR in polarized light. The Sy 2s with an
HBLR are more similar to the Sy 1s than they are to the Sy 2s without an HBLR
AD-8 for diagnosis of dementia across a variety of healthcare settings
This is a protocol for a Cochrane Review (Diagnostic test accuracy). The objectives are as follows:
To determine the diagnostic accuracy of the informantābased questionnaire ADā8, in detection of allācause (undifferentiated) dementia in adults. We will present data for each healthcare setting where ADā8 may be employed (community; primary care; secondary care)
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Plasma and Cerebrospinal fluid (CSF) Abeta42 for the differential diagnosis of Alzheimer's disease dementia in participants diagnosed with any dementia subtype in a specialist care setting
Ā© 2014 The Cochrane Collaboration. This is the protocol for a review and there is no abstract. The objectives are as follows: To determine the diagnostic accuracy of the plasma and CSF Abeta42 index tests for distinguishing Alzheimer's disease dementia from each of the other forms of dementia in people who meet the general criteria for a dementia syndrome. To investigate the heterogeneity of test accuracy in the included studies. We expect that heterogeneity will be likely and that it will be an important component of the review. The potential sources of heterogeneity, which will be used as a framework for the investigation of heterogeneity, include target population, index test, target disorder and study quality and are detailed in the analysis section
STIS spectroscopy of the emission line gas in the nuclei of nearby FR-I galaxies
We present the results of the analysis of a set of medium resolution spectra,
obtained by the Space Telescope Imaging Spectrograph on board the Hubble Space
Telescope, of the emission line gas present in the nuclei of a complete sample
of 21 nearby, early-type galaxies with radio jets (the UGC FR-I Sample). For
each galaxy nucleus we present spectroscopic data in the region of H-alpha and
the dervived kinematics.
We find that in 67% of the nuclei the gas appears to be rotating and, with
one exception, the cases where rotation is not seen are either face on or have
complex central morphologies. We find that in 62% of the nuclei the fit to the
central spectrum is improved by the inclusion of a broad component. The broad
components have a mean velocity dispersion of 1349 +/- 345 km\s and are
redshifted from the narrow line components (assuming an origin in H-alpha) by
486 +/- 443 km\s.Comment: 119 pages, 26 figures, ApJS Accepted, version with full figures
available at http://www.astro.columbia.edu/~jake/pub/fr1datapaper.pd
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