294 research outputs found
The diagnosis of food allergy: protocol for a systematic review
Full text linkBackgroundThe literature on diagnostic tests for food allergy currently lacks clear consensus regarding the accuracy and safety of different investigative approaches. The European Academy of Allergy and Clinical Immunology is in the process of developing its Guideline for Food Allergy and Anaphylaxis, and this systematic review is one of seven inter-linked evidence syntheses that are being undertaken in order to provide a state-of-the-art synopsis of the current evidence base in relation to epidemiology, prevention, diagnosis and clinical management, and impact on quality of life, which will be used to inform the formulation of clinical recommendations. The aim of this systematic review will be to assess the diagnostic accuracy of tests aimed at supporting the clinical diagnosis of IgE-mediated food allergy.MethodsThe following databases from inception to September 30, 2012 will be searched for studies of diagnostic tests: Cochrane Library (Wiley&Sons); MEDLINE (OVID); Embase (OVID); CINAHL (Ebscohost); ISI Web of Science (Thomson Web of Knowledge); TRIP Database (web http://www.tripdatabase.com webcite); and Clinicaltrials.gov (NIH web). These database searches will be supplemented by contacting an international panel of experts. Studies evaluating APT, SPT, specific-IgE, and component specific-IgE in participants of any age with suspected food allergy will be included. The reference standard will be DBPCFC in at least 50% of the participants. Studies will be quality assessed by using the QUADAS-2 instrument. We will report summary statistics such as sensitivity, specificity, and/or likelihood ratios. We will use the hierarchical summary ROC (HSROC) model to summarize the accuracy of each test and to compare the accuracy of two or more tests.DiscussionDecisions on which tests to use need to be guided by availability of tests, populations being cared for, risks, financial considerations and test properties. This review will examine papers from around the world, covering children and adults with suspected food allergy in varying populations and concentrated on four type of tests: APT, SPT, specific-IgEs, and component specific-IgEs.<br/
Rapid nucleic acid amplification tests for detection of tuberculosis and drug resistance: systematic reviews of diagnostic accuracy and impact
No full textMeta-analytic approaches for summarising and comparing the accuracy of medical tests
No full textMedical tests are essential for patient care. Evidence-based assessment of the relative accuracy of competing diagnostic tests informs clinical and policy decision making. This thesis addresses questions centred on assessing the reliability and transparency of evidence from systematic reviews and meta-analyses of comparative test accuracy, including validity of meta-analytic methods.
Case studies were used to highlight key methodological issues, and provided rationale and context for the thesis. Published systematic reviews of multiple tests were identified and used to provide a descriptive survey of recent practice. Availability of comparative accuracy studies and differences between meta-analyses of direct (head-to-head) and indirect (between-study) comparisons were assessed. Comparative meta-analysis methods were reviewed and those deemed statistically robust were empirically evaluated. Using simulation, performance of hierarchical methods for meta-analysis of a single test was investigated in challenging scenarios (e.g. few studies or sparse data) and implications for test comparisons were considered.
Poor statistical methods and incomplete reporting threatens the reliability of comparative reviews. Differences exist between direct and indirect comparisons but direct comparisons were seldom feasible because comparative studies were unavailable. Furthermore, inappropriate use of meta-analytic methods generated misleading results and conclusions. Therefore, recommendations for use of valid methods and a reporting checklist were developed
Rapid nucleic acid amplification tests for detection of tuberculosis and drug resistance: systematic reviews of diagnostic accuracy and impact
No full textAssessment of the utility of cognitive screening instruments
No full textThere are a substantial and increasing variety of test instruments available to guide the clinician in making a diagnosis of dementia. An appreciation of the methods and outputs associated with test accuracy research is useful for all clinicians, not just academics. Test accuracy is best considered using a framework that clearly defines the index test, the gold standard (reference standard) used to define the condition of interest and the population in which testing will take place. By creation of a two by two table, cross classifying the results of the index test and the reference standard, we can derive various metrics describing the properties of the test. Test accuracy studies where the condition of interest is dementia present particular challenges. Using best practice statements in the conduct, reporting and assessment of study validity can assist the interpretation of test accuracy research papers and also for planning future studies. Techniques for systematic review and meta-analysis of test accuracy studies have been developed and are being applied to certain commonly used cognitive screening tests.</p
Review of Diagnostic Test Accuracy (DTA) studies in older people
Full text linkDiagnostic Test Accuracy (DTA) describes a field of research that aims to assess how well a test is able to detect or exclude a condition of interest. Although geriatric medicine is not as reliant on investigations as other medical disciplines, almost all patient encounters with older adults will involve some form of diagnostic assessment. Thus, understanding the terminology and methods of DTA is essential for any clinician. In this review we use examples based around the diagnosis of dementia to highlight issues in DTA research. Some of these are generic to any DTA research and some are particularly pertinent to older adults. One can apply a test accuracy framework to a clinical question by defining four key components: the condition of interest; the index test(s) (i.e. the assessment(s) of interest); the reference standard (the best available method for assessing the condition of interest) and the population or healthcare setting in which testing takes place. Test accuracy is often described using complementary measures of sensitivity and specificity. However, many other metrics to describe test accuracy are available; in clinical practice predictive values may have greater utility. These and other descriptive statistics can be derived from a two by two table that cross-classifies the index test results with the reference standard results. Test performance and utility is not only determined by accuracy, other measures such as feasibility and acceptability should be considered and may be of particular importance when describing test performance in older adults with physical and cognitive impairments
Diagnostic accuracy of laparoscopy following computed tomography (CT) scanning for assessing the resectability with curative intent in pancreatic and periampullary cancer
Full text linkBackgroundSurgical resection is the only potentially curative treatment for pancreatic and periampullary cancer. A considerable proportion ofpatients undergo unnecessary laparotomy because of underestimation of the extent of the cancer on computed tomography (CT)scanning. Laparoscopy can detect metastases not visualised on CT scanning, enabling better assessment of the spread of cancer (stagingof cancer). This is an update to a previous Cochrane Review published in 2013 evaluating the role of diagnostic laparoscopy in assessingthe resectability with curative intent in people with pancreatic and periampullary cancer.ObjectivesTo determine the diagnostic accuracy of diagnostic laparoscopy performed as an add-on test to CT scanning in the assessment ofcurative resectability in pancreatic and periampullary cancer.Search methodsWe searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via PubMed, EMBASE via OvidSP (frominception to 15 May 2016), and Science Citation Index Expanded (from 1980 to 15 May 2016).Selection criteriaWe included diagnostic accuracy studies of diagnostic laparoscopy in people with potentially resectable pancreatic and periampullarycancer on CT scan, where confirmation of liver or peritoneal involvement was by histopathological examination of suspicious (liver orperitoneal) lesions obtained at diagnostic laparoscopy or laparotomy. We accepted any criteria of resectability used in the studies. Weincluded studies irrespective of language, publication status, or study design (prospective or retrospective). We excluded case-controlstudies.Data collection and analysisTwo review authors independently performed data extraction and quality assessment using the QUADAS-2 tool. The specificity ofdiagnostic laparoscopy in all studies was 1 because there were no false positives since laparoscopy and the reference standard are oneand the same if histological examination after diagnostic laparoscopy is positive. The sensitivities were therefore meta-analysed using aunivariate random-effects logistic regression model. The probability of unresectability in people who had a negative laparoscopy (posttestprobability for people with a negative test result) was calculated using themedian probability of unresectability (pre-test probability)from the included studies, and the negative likelihood ratio derived from the model (specificity of 1 assumed). The difference betweenthe pre-test and post-test probabilities gave the overall added value of diagnostic laparoscopy compared to the standard practice of CTscan staging alone.Main resultsWe included 16 studies with a total of 1146 participants in the meta-analysis. Only one study including 52 participants had a low riskof bias and low applicability concern in the patient selection domain. The median pre-test probability of unresectable disease after CTscanning across studies was 41.4% (that is 41 out of 100 participants who had resectable cancer after CT scan were found to haveunresectable disease on laparotomy). The summary sensitivity of diagnostic laparoscopy was 64.4% (95% confidence interval (CI)50.1% to 76.6%). Assuming a pre-test probability of 41.4%, the post-test probability of unresectable disease for participants with anegative test result was 0.20 (95% CI 0.15 to 0.27). This indicates that if a person is said to have resectable disease after diagnosticlaparoscopy and CT scan, there is a 20% probability that their cancer will be unresectable compared to a 41% probability for thosereceiving CT alone.A subgroup analysis of people with pancreatic cancer gave a summary sensitivity of 67.9% (95% CI 41.1% to 86.5%). The post-testprobability of unresectable disease after being considered resectable on both CT and diagnostic laparoscopy was 18% compared to40.0% for those receiving CT alone.Authors’ conclusionsDiagnostic laparoscopy may decrease the rate of unnecessary laparotomy in people with pancreatic and periampullary cancer foundto have resectable disease on CT scan. On average, using diagnostic laparoscopy with biopsy and histopathological confirmation ofsuspicious lesions prior to laparotomy would avoid 21 unnecessary laparotomies in 100 people in whom resection of cancer withcurative intent is planned.<br/
Accuracy of single progesterone test to predict early pregnancy outcome in women with pain or bleeding: Meta-analysis of cohort studies
Full text linkObjective To determine the accuracy with which a single progesterone measurement in early pregnancy discriminates between viable and non-viable pregnancy. Design Systematic review and meta-analysis of diagnostic accuracy studies. Data sources Medline, Embase, CINAHL, Web of Science, ProQuest, Conference Proceedings Citation Index, and the Cochrane Library from inception until April 2012, plus reference lists of relevant studies. Study selection Studies were selected on the basis of participants (women with spontaneous pregnancy of less than 14 weeks of gestation); test (single serum progesterone measurement); outcome (viable intrauterine pregnancy, miscarriage, or ectopic pregnancy) diagnosed on the basis of combinations of pregnancy test, ultrasound scan, laparoscopy, and histological examination; design (cohort studies of test accuracy); and sufficient data being reported. Results 26 cohort studies, including 9436 pregnant women, were included, consisting of 7 studies in women with symptoms and inconclusive ultrasound assessment and 19 studies in women with symptoms alone. Among women with symptoms and inconclusive ultrasound assessments, the progesterone test (5 studies with 1998 participants and cut-off values from 3.2 to 6 ng/mL) predicted a non-viable pregnancy with pooled sensitivity of 74.6% (95% confidence interval 50.6% to 89.4%), specificity of 98.4% (90.9% to 99.7%), positive likelihood ratio of 45 (7.1 to 289), and negative likelihood ratio of 0.26 (0.12 to 0.57). The median prevalence of a non-viable pregnancy was 73.2%, and the probability of a non-viable pregnancy was raised to 99.2% if the progesterone was low. For women with symptoms alone, the progesterone test had a higher specificity when a threshold of 10 ng/mL was used (9 studies with 4689 participants) and predicted a non-viable pregnancy with pooled sensitivity of 66.5% (53.6% to 77.4%), specificity of 96.3% (91.1% to 98.5%), positive likelihood ratio of 18 (7.2 to 45), and negative likelihood ratio of 0.35 (0.24 to 0.50). The probability of a non-viable pregnancy was raised from 62.9% to 96.8%. Conclusion A single progesterone measurement for women in early pregnancy presenting with bleeding or pain and inconclusive ultrasound assessments can rule out a viable pregnancy.Jorine Verhaegen, Ioannis D Gallos, Norah M van Mello, Mohamed Abdel-Aziz, Yemisi Takwoingi, Hoda Harb, Jonathan J Deeks, Ben W J Mol, Arri Coomarasam
Systematic Reviews of Diagnostic Test Accuracy
No full textMore and more systematic reviews of diagnostic test accuracy studies are being published, but they can be methodologically challenging. In this paper, the authors present some of the recent developments in the methodology for conducting systematic reviews of diagnostic test accuracy studies. Restrictive electronic search filters are discouraged, as is the use of summary quality scores. Methods for meta-analysis should take into account the paired nature of the estimates and their dependence on threshold. Authors of these reviews are advised to use the hierarchical summary receiver-operating characteristic or the bivariate model for the data analysis. Challenges that remain are the poor reporting of original diagnostic test accuracy studies and difficulties with the interpretation of the results of diagnostic test accuracy research
Writing a plain language summary
No full textA plain language summary is a standalone summary of a Cochrane systematic review written in plain language. It provides rapid access to the contents of the review. Plain language summaries can be used to facilitate shared decision-making between individuals and their healthcare providers. The plain language summary aims to summarize the review in a straightforward style that can be understood by consumers of health care. Plain language summaries are mandatory for all Cochrane systematic reviews. This chapter discusses the challenges and suggested approaches for writing plain language summaries for different types of systematic review of test accuracy questions. Because of the difficulties in understanding measures of test accuracy, the potential audience for a plain language summary for a systematic review of test accuracy is likely to be wide, including the public, policy makers and anyone who talks to the public about health, for example doctors, nurses, journalists and patient groups.</p
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