131 research outputs found
Studies to inform the methods for Cochrane systematic reviews of diagnostic accuracy in stroke medicine
Background
A variety of tests are used in clinical practice to help the diagnostic process and so
improve patient care. Many aspects of stroke management depend on accurate and
rapid diagnosis. Brain imaging, including CT or MRI, is necessary to identify the
location and extent of the cerebral lesion, and to determine the pathological type of
stroke and its likely cause. Current treatments - such as thrombolysis - for ischaemic
stroke have increased the need for clear evidence on which imaging test is optimal
for diagnosis in the acute phase of stroke.
Systematic reviews of diagnostic test accuracy may provide evidence on the best use
of a diagnostic test in clinical practice and help clinicians to decide among alternative
tests. The Cochrane Collaboration has recently included systematic reviews of
diagnostic test accuracy within its remit. However, to prepare Cochrane systematic
reviews of diagnostic test accuracy is challenging because the methods for such
reviews are still in a state of flux.
Materials and methods
The research work undertaken for this thesis addresses four relevant methodological
aspects of such reviews and, I hope, will contribute to informing the development of
the methods for Cochrane systematic reviews of test accuracy:
i) I assessed the quality of reporting of imaging studies in stroke medicine
published between 1995 and 2008 with the current STAndards for the
Reporting of Diagnostic accuracy studies (STARD) criteria;
ii) I assessed the magnitude of publication bias in diagnostic accuracy
studies in stroke medicine, by reviewing all diagnostic abstracts presented
at two international stroke meetings between 1995 and 2004 and so
evaluating the characteristics and findings of the identified abstracts;
iii) I have evaluated the methods for preparing reviews of test accuracy by
undertaking a pilot review according to the draft recommendations of the
Cochrane Diagnostic Test Accuracy Working Group;
iv) I conducted a survey to assess a) how well clinicians and health
professionals interpret findings of Cochrane systematic reviews of
diagnostic accuracy presented in summary documents; and b) what is the
best format for summarising findings of Cochrane reviews of diagnostic
accuracy.
Conclusions
In conclusion, methodological issues concerning the validity and reliability of
findings of studies included in systematic reviews of diagnostic accuracy remain of
fundamental importance. More empirical evidence is needed to address potential
biases such as reporting bias and publication bias. To allow dissemination of
diagnostic reviews findings in clinical practice better ways of communicating main
characteristics and key results of systematic reviews of diagnostic accuracy should be
considered. In the current literature, the quality of reporting and methodological quality of
imaging studies for the diagnosis of stroke is less than satisfactory and leaves room
for improvement. This is worrying, especially if current health imaging policies are
in fact based on poor quality evidence and hence scarce health resources may not
being deployed as effectively as they could be
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS) databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history, and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among national and international groups
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS)
databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history,
and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active
interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most
relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical
centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database
Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data
of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in
high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the
methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among
national and international groups
Test of lepton universality in decays
The first simultaneous test of muon-electron universality using
and decays is performed, in two ranges of the dilepton
invariant-mass squared, . The analysis uses beauty mesons produced in
proton-proton collisions collected with the LHCb detector between 2011 and
2018, corresponding to an integrated luminosity of 9 . Each
of the four lepton universality measurements reported is either the first in
the given interval or supersedes previous LHCb measurements. The
results are compatible with the predictions of the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-046.html (LHCb
public pages
Precision measurement of violation in the penguin-mediated decay
A flavor-tagged time-dependent angular analysis of the decay
is performed using collision data collected
by the LHCb experiment at % at TeV, the center-of-mass energy of
13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The
-violating phase and direct -violation parameter are measured
to be rad and
, respectively, assuming the same values
for all polarization states of the system. In these results, the
first uncertainties are statistical and the second systematic. These parameters
are also determined separately for each polarization state, showing no evidence
for polarization dependence. The results are combined with previous LHCb
measurements using collisions at center-of-mass energies of 7 and 8 TeV,
yielding rad and . This is the most precise study of time-dependent violation
in a penguin-dominated meson decay. The results are consistent with
symmetry and with the Standard Model predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-001.html (LHCb
public pages
Observation of Two New Excited Ξb0 States Decaying to Λb0 K-π+
Two narrow resonant states are observed in the Λb0K-π+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Λb0K-π+ system indicates that these are excited Ξb0 baryons. The masses of the Ξb(6327)0 and Ξb(6333)0 states are m[Ξb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Ξb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Δm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Λb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Γ[Ξb(6327)0]<2.20(2.56) and Γ[Ξb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Ξb0 resonances
Observation of a resonant structure near the threshold in the decay
An amplitude analysis of the decay is carried out to
study for the first time its intermediate resonant contributions, using
proton-proton collision data collected with the LHCb detector at centre-of-mass
energies of 7, 8 and 13 TeV. A near-threshold peaking structure, referred to as
, is observed in the invariant-mass spectrum with
significance greater than 12 standard deviations. The mass, width and the
quantum numbers of the structure are measured to be MeV,
MeV and , respectively, where the first
uncertainties are statistical and the second systematic. The properties of the
new structure are consistent with recent theoretical predictions for a state
composed of quarks. Evidence for an additional structure is
found around 4140 MeV in the invariant mass, which might be
caused either by a new resonance with the assignment or by a coupled-channel effect.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-018.html (LHCb
public pages
Measurement of the differential branching fraction
The branching fraction of the rare decay is measured for the first time, in the squared dimuon mass
intervals, , excluding the and regions. The data
sample analyzed was collected by the LHCb experiment at center-of-mass energies
of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of $9\
\mathrm{fb}^{-1}q^{2}q^{2} >15.0\
\mathrm{GeV}^2/c^4$, where theoretical predictions have the smallest model
dependence, agrees with the predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-050.html (LHCb
public pages
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Study of the and states in decays
The decays are studied using a data
set corresponding to an integrated luminosity of 9fb collected with the
LHCb detector in proton-proton collisions between 2011 and 2018. Precise
measurements of the ratios of branching fractions with the intermediate
, and states are reported. The decay
of with is observed for the first time with a significance of 5.1
standard deviations. The mass differences between the ,
and states are measured to be resulting in the
most precise determination of the mass. The width of the
state is found to be below 5.2MeV at 90\% confidence level. The
Breit-Wigner width of the state is measured to be which is inconsistent with zero by 5.5 standard deviations
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