Background
Ferumoxytol has been studied as an alternative to gadolinium‐based MRI contrast agents, but regulatory body warnings currently limit its use.
Purpose
Estimate the adverse event rate in ...patients undergoing MRI with ferumoxytol as a contrast agent.
Study Type
Systematic review.
Population
Thirty‐nine studies including 5411 ferumoxytol administrations in 4336 patients.
Assessment
Multiple databases were searched for studies using ferumoxytol as an off‐label MRI contrast agent in any patient population as of April 2020. Studies were eligible for inclusion if they reported the number and severity of adverse events (classified by American College of Radiology ACR severity of acute reactions). Risk of bias was assessed using the ROBINS‐I tool.
Statistical Tests
The proportion of administrations with adverse events was calculated using random effects meta‐analysis of proportions.
Results
No deaths related to ferumoxytol administration were reported. Sixteen studies reported immediate adverse events in 3849 patients undergoing 4901 ferumoxytol administrations. Ninety‐seven immediate adverse events were reported and the pooled adverse event proportion for immediate adverse events was 0.02 (95% confidence interval CI 0.02–0.02). Twenty‐three studies reported time‐unspecified adverse events in 487 patients undergoing 510 ferumoxytol administrations. Five time‐unspecified adverse events were reported; the pooled adverse event proportion for time‐unspecified adverse events was 0.01 (95% CI 0.00–0.04). 88% of adverse events were mild (90/102), 11% (11/102) were moderate, and 1% (1/102) was severe. Sixteen studies were at low risk of bias, 23 studies were at serious risk of bias. Subgroup analysis by patient population revealed no significant variability (adult vs. pediatric). No studies evaluated the use of ferumoxytol as an alternative to patients who had a prior hypersensitivity reaction to gadolinium‐based contrast agents (GBCAs).
Data Conclusion
The overall adverse event rate for off‐label ferumoxytol use as an MRI contrast agent is 2%, with rare severe reactions and no deaths. To date, there are no studies evaluating the safety of ferumoxytol as an alternative to GBCAs in patients with a prior hypersensitivity reaction.
Level of Evidence
2
Technical Efficacy Stage
5
The purpose of this study is to evaluate whether imaging diagnostic test accuracy (DTA) studies with positive conclusions or titles have a shorter time to publication than those with nonpositive ...(i.e., negative or neutral) conclusions or titles.
We included primary imaging DTA studies from systematic reviews published in 2015. The conclusion and title of each study were extracted, and their positivity was classified independently in duplicate. The time from study completion to publication was extracted and calculated. A Cox regression model was used to evaluate associations of conclusion and title positivity with time to publication, with adjustment made for potentially confounding variables.
A total of 774 imaging DTA studies were included; time from study completion to publication could be calculated for 516 studies. The median time from completion to publication was 18 months (interquartile range, 13-26 months) for the 413 studies with positive conclusions, 23 months (interquartile range, 16-33 months) for the 63 studies with neutral conclusions, and 25 months (interquartile range, 15-38 months) for the 40 studies with negative conclusions. A positive conclusion was associated with a shorter time from study completion to publication compared with a non-positive conclusion (hazard ratio, 1.31; 95% CI, 1.02-1.68). Of all included studies, 39 (5%) had positive titles, 731 (94%) had neutral titles, and 4 (< 1%) had negative titles. Positive titles were not significantly associated with a shorter time to study publication (hazard ratio, 1.12; 95% CI, 0.75-1.69).
Positive conclusions (but not titles) were associated with a shorter time from study completion to publication. This finding may contribute to an overrepresentation of positive results in the imaging DTA literature.
Purpose:
To examine if tweeting bias exists within imaging literature by determining if diagnostic test accuracy (DTA) studies with positive titles or conclusions are tweeted more than non-positive ...studies.
Methods:
DTA studies published between October 2011 to April 2016 were included. Positivity of titles and conclusions were assessed independently and in duplicate, with disagreements resolved by consensus. A negative binomial regression analysis controlling for confounding variables was performed to assess the relationship between title or conclusion positivity and tweets an article received in the 100 days post-publication.
Results:
354 DTA studies were included. Twenty-four (7%) titles and 300 (85%) conclusions were positive (or positive with qualifier); 1 (0.3%) title and 23 (7%) conclusions were negative; and 329 (93%) titles and 26 (7%) conclusions were neutral. Studies with positive, negative, and neutral titles received a mean of 0.38, 0.00, and 0.45 tweets per study; while those with positive, negative, and neutral conclusions received a mean of 0.44, 0.61, and 0.38 tweets per study. Regression coefficients were -0.05 (SE 0.46) for positive relative to non-positive titles, and -0.09 (SE 0.31) for positive relative to non-positive conclusions. The positivity of the title (P = 0.91) or conclusion (P = 0.76) was not significantly associated with the number of tweets an article received.
Conclusions:
The positivity of the title or conclusion for DTA studies does not influence the amount of tweets it receives suggesting that tweet bias is not present among imaging diagnostic accuracy studies. Study protocol available at https://osf.io/hdk2m/
We provide a unique Canadian perspective on the medicolegal risks associated with imaging acute appendicitis, incorporating data requested from the Canadian Medical Protective Association (CMPA) on ...closed medicolegal cases over the past decade. We include a review of current clinical and imaging guidelines in the diagnosis and management of this common emergency room presentation. A case-based approach is implemented in this article to explore ways to mitigate potential errors in the diagnosis of acute appendicitis.
Our March 2021 edition of this review showed thoracic imaging computed tomography (CT) to be sensitive and moderately specific in diagnosing COVID-19 pneumonia. This new edition is an update of the ...review.
Our objectives were to evaluate the diagnostic accuracy of thoracic imaging in people with suspected COVID-19; assess the rate of positive imaging in people who had an initial reverse transcriptase polymerase chain reaction (RT-PCR) negative result and a positive RT-PCR result on follow-up; and evaluate the accuracy of thoracic imaging for screening COVID-19 in asymptomatic individuals. The secondary objective was to assess threshold effects of index test positivity on accuracy.
We searched the COVID-19 Living Evidence Database from the University of Bern, the Cochrane COVID-19 Study Register, The Stephen B. Thacker CDC Library, and repositories of COVID-19 publications through to 17 February 2021. We did not apply any language restrictions.
We included diagnostic accuracy studies of all designs, except for case-control, that recruited participants of any age group suspected to have COVID-19. Studies had to assess chest CT, chest X-ray, or ultrasound of the lungs for the diagnosis of COVID-19, use a reference standard that included RT-PCR, and report estimates of test accuracy or provide data from which we could compute estimates. We excluded studies that used imaging as part of the reference standard and studies that excluded participants with normal index test results.
The review authors independently and in duplicate screened articles, extracted data and assessed risk of bias and applicability concerns using QUADAS-2. We presented sensitivity and specificity per study on paired forest plots, and summarized pooled estimates in tables. We used a bivariate meta-analysis model where appropriate.
We included 98 studies in this review. Of these, 94 were included for evaluating the diagnostic accuracy of thoracic imaging in the evaluation of people with suspected COVID-19. Eight studies were included for assessing the rate of positive imaging in individuals with initial RT-PCR negative results and positive RT-PCR results on follow-up, and 10 studies were included for evaluating the accuracy of thoracic imaging for imagining asymptomatic individuals. For all 98 included studies, risk of bias was high or unclear in 52 (53%) studies with respect to participant selection, in 64 (65%) studies with respect to reference standard, in 46 (47%) studies with respect to index test, and in 48 (49%) studies with respect to flow and timing. Concerns about the applicability of the evidence to: participants were high or unclear in eight (8%) studies; index test were high or unclear in seven (7%) studies; and reference standard were high or unclear in seven (7%) studies. Imaging in people with suspected COVID-19 We included 94 studies. Eighty-seven studies evaluated one imaging modality, and seven studies evaluated two imaging modalities. All studies used RT-PCR alone or in combination with other criteria (for example, clinical signs and symptoms, positive contacts) as the reference standard for the diagnosis of COVID-19. For chest CT (69 studies, 28285 participants, 14,342 (51%) cases), sensitivities ranged from 45% to 100%, and specificities from 10% to 99%. The pooled sensitivity of chest CT was 86.9% (95% confidence interval (CI) 83.6 to 89.6), and pooled specificity was 78.3% (95% CI 73.7 to 82.3). Definition for index test positivity was a source of heterogeneity for sensitivity, but not specificity. Reference standard was not a source of heterogeneity. For chest X-ray (17 studies, 8529 participants, 5303 (62%) cases), the sensitivity ranged from 44% to 94% and specificity from 24 to 93%. The pooled sensitivity of chest X-ray was 73.1% (95% CI 64. to -80.5), and pooled specificity was 73.3% (95% CI 61.9 to 82.2). Definition for index test positivity was not found to be a source of heterogeneity. Definition for index test positivity and reference standard were not found to be sources of heterogeneity. For ultrasound of the lungs (15 studies, 2410 participants, 1158 (48%) cases), the sensitivity ranged from 73% to 94% and the specificity ranged from 21% to 98%. The pooled sensitivity of ultrasound was 88.9% (95% CI 84.9 to 92.0), and the pooled specificity was 72.2% (95% CI 58.8 to 82.5). Definition for index test positivity and reference standard were not found to be sources of heterogeneity. Indirect comparisons of modalities evaluated across all 94 studies indicated that chest CT and ultrasound gave higher sensitivity estimates than X-ray (P = 0.0003 and P = 0.001, respectively). Chest CT and ultrasound gave similar sensitivities (P=0.42). All modalities had similar specificities (CT versus X-ray P = 0.36; CT versus ultrasound P = 0.32; X-ray versus ultrasound P = 0.89). Imaging in PCR-negative people who subsequently became positive For rate of positive imaging in individuals with initial RT-PCR negative results, we included 8 studies (7 CT, 1 ultrasound) with a total of 198 participants suspected of having COVID-19, all of whom had a final diagnosis of COVID-19. Most studies (7/8) evaluated CT. Of 177 participants with initially negative RT-PCR who had positive RT-PCR results on follow-up testing, 75.8% (95% CI 45.3 to 92.2) had positive CT findings. Imaging in asymptomatic PCR-positive people For imaging asymptomatic individuals, we included 10 studies (7 CT, 1 X-ray, 2 ultrasound) with a total of 3548 asymptomatic participants, of whom 364 (10%) had a final diagnosis of COVID-19. For chest CT (7 studies, 3134 participants, 315 (10%) cases), the pooled sensitivity was 55.7% (95% CI 35.4 to 74.3) and the pooled specificity was 91.1% (95% CI 82.6 to 95.7).
Chest CT and ultrasound of the lungs are sensitive and moderately specific in diagnosing COVID-19. Chest X-ray is moderately sensitive and moderately specific in diagnosing COVID-19. Thus, chest CT and ultrasound may have more utility for ruling out COVID-19 than for differentiating SARS-CoV-2 infection from other causes of respiratory illness. The uncertainty resulting from high or unclear risk of bias and the heterogeneity of included studies limit our ability to confidently draw conclusions based on our results.
The purpose of this study was to examine the existence of selective citation practices in the imaging literature by assessing whether diagnostic accuracy studies with positive titles or conclusions ...are cited more frequently than those with negative (or neutral) titles or conclusions.
MEDLINE was searched for meta-analyses of diagnostic accuracy studies published in imaging journals from January 2005 to April 2016. Primary studies from the meta-analyses were screened for eligibility. Titles and conclusions were classified independently in duplicate. A negative binomial regression analysis controlling for several confounding variables was performed to obtain regression coefficients;
values were obtained via likelihood ratio testing.
A total of 995 primary studies were included. Fifty-one titles (5.1%) and 782 conclusions (78.6%) were positive or positive with qualifiers; 942 titles (94.7%) and 127 conclusions (12.8%) were neutral; and two titles (0.02%) and 86 conclusions (8.6%) were negative. Studies with positive, neutral, and negative titles were cited a mean of 0.66, 0.50, and 0.06 times per month. Studies with positive, neutral, and negative conclusions were cited a mean of 0.54, 0.42, and 0.34 times per month. Regression coefficients were 1.10 (95% CI, -0.08 to 2.20) and 0.91 (95% CI, -0.27 to 2.00) for positive and neutral titles, relative to negative titles. Regression coefficients were 0.19 (95% CI, 0.03-0.35) and 0.08 (95% CI, -0.12 to 0.27) for positive and neutral conclusions, relative to negative conclusions. Title and conclusion positivity demonstrated positive association with citation rate (
= 0.031 for both).
Studies with positive titles or conclusions are cited more frequently in imaging diagnostic accuracy literature. This difference may contribute to overestimation of the accuracy of a test and, consequently, suboptimal patient outcomes.
Purpose
The purpose of this methodological review was to determine the extent to which comparative imaging systematic reviews of diagnostic test accuracy (DTA) use primary studies with comparative or ...non-comparative designs.
Methods
MEDLINE was used to identify DTA systematic reviews published in imaging journals between January 2000 and May 2018. Inclusion criteria: systematic reviews comparing at least two index tests (one of which was imaging-based); review characteristics were extracted. Study design and other characteristics of primary studies included in the systematic reviews were evaluated.
Results
One hundred three comparative imaging reviews were included; 11 (11%) included only comparative studies, 12 (11%) included only non-comparative primary studies, and 80 (78%) included both comparative and non-comparative primary studies. For reviews containing both comparative and non-comparative primary studies, the median proportion of non-comparative primary studies was 81% (IQR 57–90%). Of 92 reviews that included non-comparative primary studies, 86% did not recognize this as a limitation. Furthermore, among 4182 primary studies, 3438 (82%) were non-comparative and 744 (18%) were comparative in design.
Conclusion
Most primary studies included in comparative imaging reviews are non-comparative in design and awareness of the risk of bias associated with this is low. This may lead to incorrect conclusions about the relative accuracy of diagnostic tests and be counter-productive for informing guidelines and funding decisions about imaging tests.
Key Points
• Few comparative accuracy imaging reviews include only primary studies with optimal comparative study designs. Among the rest, few recognize the risk of bias conferred from inclusion of primary studies with non-comparative designs.
• The demand for accurate comparative accuracy data combined with minimal awareness of valid comparative study designs may lead to counter-productive research and inadequately supported clinical decisions for diagnostic tests.
• Using comparative accuracy imaging reviews with a high risk of bias to inform guidelines and funding decisions may have detrimental impacts on patient care.
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