Zhivko Zhelev

Diagnostic accuracy of single baseline measurement of Elecsys Troponin T high-sensitive assay for diagnosis of acute myocardial infarction in emergency department: systematic review and meta-analysis

Objective To obtain summary estimates of the accuracy of a single baseline measurement of the Elecsys Troponin T high-sensitive assay (Roche Diagnostics) for the diagnosis of acute myocardial infarction in patients presenting to the emergency department. Design Systematic review and meta-analysis of diagnostic test accuracy studies. Data sources Medline, Embase, and other relevant electronic databases were searched for papers published between January 2006 and December 2013. Study selection Studies were included if they evaluated the diagnostic accuracy of a single baseline measurement of Elecsys Troponin T high-sensitive assay for the diagnosis of acute myocardial infarction in patients presenting to the emergency department with suspected acute coronary syndrome. Study appraisal and data synthesis The first author screened all titles and abstracts identified through the searches and selected all potentially relevant papers. The screening of the full texts, the data extraction, and the methodological quality assessment, using the adapted QUADAS-2 tool, were conducted independently by two reviewers with disagreements being resolved through discussion or arbitration. If appropriate, meta-analysis was conducted using the hierarchical bivariate model. Results Twenty three studies reported the performance of the evaluated assay at presentation. The results for 14 ng/L and 3-5 ng/L cut-off values were pooled separately. At 14 ng/L (20 papers), the summary sensitivity was 89.5% (95% confidence interval 86.3% to 92.1%) and the summary specificity was 77.1% (68.7% to 83.7%). At 3-5 ng/L (six papers), the summary sensitivity was 97.4% (94.9% to 98.7%) and the summary specificity was 42.4% (31.2% to 54.5%). This means that if 21 of 100 consecutive patients have the target condition (21%, the median prevalence across the studies), 2 (95% confidence interval 2 to 3) of 21 patients with acute myocardial infarction will be missed (false negatives) if 14 ng/L is used as a cut-off value and 18 (13 to 25) of 79 patients without acute myocardial infarction will test positive (false positives). If the 3-5 ng/L cut-off value is used, <1 (0 to 1) patient with acute myocardial infarction will be missed and 46 (36 to 54) patients without acute myocardial infarction will test positive. Conclusions The results indicate that a single baseline measurement of the Elecsys Troponin T high-sensitive assay could be used to rule out acute myocardial infarction if lower cut-off values such as 3 ng/L or 5 ng/L are used. However, this method should be part of a comprehensive triage strategy and may not be appropriate for patients who present less than three hours after symptom onset. Care must also be exercised because of the higher imprecision of the evaluated assay and the greater effect of lot-to-lot reagent variation at low troponin concentrations. Systematic review registration PROSPERO registration number CRD42013003926.

A qualitative study into the difficulties experienced by healthcare decision makers when reading a Cochrane diagnostic test accuracy review

BackgroundCochrane reviews are one of the best known and most trusted sources of evidence-based information in health care. While steps have been taken to make Cochrane intervention reviews accessible to a diverse readership, little is known about the accessibility of the newcomer to the Cochrane library: diagnostic test accuracy reviews (DTARs). The current qualitative study explored how healthcare decision makers, who varied in their knowledge and experience with test accuracy research and systematic reviews, read and made sense of DTARs.MethodsA purposive sample of clinicians, researchers and policy makers (n = 21) took part in a series of think-aloud interviews, using as interview material the first three DTARs published in the Cochrane library. Thematic qualitative analysis of the transcripts was carried out to identify patterns in participants’ ‘reading’ and interpretation of the reviews and the difficulties they encountered.ResultsParticipants unfamiliar with the design and methodology of DTARs found the reviews largely inaccessible and experienced a range of difficulties stemming mainly from the mismatch between background knowledge and level of explanation provided in the text. Experience with systematic reviews of interventions did not guarantee better understanding and, in some cases, led to confusion and misinterpretation. These difficulties were further exacerbated by poor layout and presentation, which affected even those with relatively good knowledge of DTARs and had a negative impact not only on their understanding of the reviews but also on their motivation to engage with the text. Comparison between the readings of the three reviews showed that more accessible presentation, such as presenting the results as natural frequencies, significantly increased participants’ understanding.ConclusionsThe study demonstrates that authors and editors should pay more attention to the presentation as well as the content of Cochrane DTARs, especially if the reports are aimed at readers with various levels of background knowledge and experience. It also raises the question as to the anticipated target audience of the reports and suggests that different groups of healthcare decision-makers may require different modes of presentation.

A programme of studies including assessment of diagnostic accuracy of school hearing screening tests and a cost-effectiveness model of school entry hearing screening programmes

BACKGROUND Identification of permanent hearing impairment at the earliest possible age is crucial to maximise the development of speech and language. Universal newborn hearing screening identifies the majority of the 1 in 1000 children born with a hearing impairment, but later onset can occur at any time and there is no optimum time for further screening. A universal but non-standardised school entry screening (SES) programme is in place in many parts of the UK but its value is questioned. OBJECTIVES To evaluate the diagnostic accuracy of hearing screening tests and the cost-effectiveness of the SES programme in the UK. DESIGN Systematic review, case-control diagnostic accuracy study, comparison of routinely collected data for services with and without a SES programme, parental questionnaires, observation of practical implementation and cost-effectiveness modelling. SETTING Second- and third-tier audiology services; community. PARTICIPANTS Children aged 4-6 years and their parents. MAIN OUTCOME MEASURES Diagnostic accuracy of two hearing screening devices, referral rate and source, yield, age at referral and cost per quality-adjusted life-year. RESULTS The review of diagnostic accuracy studies concluded that research to date demonstrates marked variability in the design, methodological quality and results. The pure-tone screen (PTS) (Amplivox, Eynsham, UK) and HearCheck (HC) screener (Siemens, Frimley, UK) devices had high sensitivity (PTS ≥ 89%, HC ≥ 83%) and specificity (PTS ≥ 78%, HC ≥ 83%) for identifying hearing impairment. The rate of referral for hearing problems was 36% lower with SES (Nottingham) relative to no SES (Cambridge) [rate ratio 0.64, 95% confidence interval (CI) 0.59 to 0.69; p < 0.001]. The yield of confirmed cases did not differ between areas with and without SES (rate ratio 0.82, 95% CI 0.63 to 1.06; p = 0.12). The mean age of referral did not differ between areas with and without SES for all referrals but children with confirmed hearing impairment were older at referral in the site with SES (mean age difference 0.47 years, 95% CI 0.24 to 0.70 years; p < 0.001). Parental responses revealed that the consequences to the family of the referral process are minor. A SES programme is unlikely to be cost-effective and, using base-case assumptions, is dominated by a no screening strategy. A SES programme could be cost-effective if there are fewer referrals associated with SES programmes or if referrals occur more quickly with SES programmes. CONCLUSIONS A SES programme using the PTS or HC screener is unlikely to be effective in increasing the identified number of cases with hearing impairment and lowering the average age at identification and is therefore unlikely to represent good value for money. This finding is, however, critically dependent on the results of the observational study comparing Nottingham and Cambridge, which has limitations. The following are suggested: systematic reviews of the accuracy of devices used to measure hearing at school entry; characterisation and measurement of the cost-effectiveness of different approaches to the ad-hoc referral system; examination of programme specificity as opposed to test specificity; further observational comparative studies of different programmes; and opportunistic trials of withdrawal of SES programmes. TRIAL REGISTRATION Current Controlled Trials ISRCTN61668996. FUNDING This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 36. See the NIHR Journals Library website for further project information.

Effectiveness of interventions to reduce ordering of thyroid function tests: a systematic review

Objectives To evaluate the effectiveness of behaviour changing interventions targeting ordering of thyroid function tests. Design Systematic review. Data sources MEDLINE, EMBASE and the Cochrane Database up to May 2015. Eligibility criteria for selecting studies We included studies evaluating the effectiveness of behaviour change interventions aiming to reduce ordering of thyroid function tests. Randomised controlled trials (RCTs), non-randomised controlled studies and before and after studies were included. There were no language restrictions. Study appraisal and synthesis methods 2 reviewers independently screened all records identified by the electronic searches and reviewed the full text of any deemed potentially relevant. Study details were extracted from the included papers and their methodological quality assessed independently using a validated tool. Disagreements were resolved through discussion and arbitration by a third reviewer. Meta-analysis was not used. Results 27 studies (28 papers) were included. They evaluated a range of interventions including guidelines/protocols, changes to funding policy, education, decision aids, reminders and audit/feedback; often intervention types were combined. The most common outcome measured was the rate of test ordering, but the effect on appropriateness, test ordering patterns and cost were also measured. 4 studies were RCTs. The majority of the studies were of poor or moderate methodological quality. The interventions were variable and poorly reported. Only 4 studies reported unsuccessful interventions but there was no clear pattern to link effect and intervention type or other characteristics. Conclusions The results suggest that behaviour change interventions are effective particularly in reducing the volume of thyroid function tests. However, due to the poor methodological quality and reporting of the studies, the likely presence of publication bias and the questionable relevance of some interventions to current day practice, we are unable to draw strong conclusions or recommend the implementation of specific intervention types. Further research is thus justified. Trial registration number CRD42014006192.

Redesigning the diagnostic pathway for chest pain patients in emergency departments

Patients presenting with chest pain at an emergency department in the United Kingdom receive troponin tests to assess the likelihood of an acute myocardial infarction (AMI). Until recently, serial testing with two blood samples separated by at least six hours was necessary in order to analyse the change in troponin levels over time. New high-sensitivity troponin tests, however, allow the inter-test time to be shortened from six to three hours. Recent evidence also suggests that the new generation of troponin tests can be used to rule out AMI on the basis of a single test if patients at low risk of AMI present with very low cardiac troponin levels more than three hours after onset of worst pain. This paper presents a discrete event simulation model to assess the likely impact on the number of hospital admissions if emergency departments adopt strategies for serial and single testing based on the use of high-sensitivity troponin. Data sets from acute trusts in the South West of England are used to quantify the resulting benefits.

A directly comparative two-gate case–control diagnostic accuracy study of the pure tone screen and HearCheck screener tests for identifying hearing impairment in school children

Objectives This study directly compared the accuracy of two audiometry-based tests for screening school children for hearing impairment: the currently used test, pure tone screen and a device newly applied to children, HearCheck Screener. Design Two-gate case–control diagnostic test accuracy study. Setting and participants Hearing impaired children (‘intended cases’) aged 4–6 years were recruited between February 2013 and August 2014 from collaborating audiology services. Children with no previously identified impairment (‘intended controls’) were recruited from Foundation and Year 1 of schools between February 2013 and June 2014 in central England. The reference standard was pure tone audiometry. Tests were administered at Nottingham Hearing Biomedical Research Unit or, for some intended cases only, in the participant’s home. Main outcome measures Sensitivity and specificity of the pure tone screen and HearCheck tests based on pure tone audiometry result as reference standard. Results 315 children (630 ears) were recruited; 75 from audiology services and 240 from schools. Full test and reference standard data were obtained for 600 ears; 155 ears were classified as truly impaired and 445 as truly hearing based on the pure tone audiometry assessment. Sensitivity was estimated to be 94.2% (95% CI 89.0% to 97.0%) for pure tone screen and 89.0% (95% CI 82.9% to 93.1%) for HearCheck (difference=5.2% favouring pure tone screen; 95% CI 0.2% to 10.1%; p=0.02). Estimates for specificity were 82.2% (95% CI 77.7% to 86.0%) for pure tone screen and 86.5% (95% CI 82.5% to 89.8%) for HearCheck (difference=4.3% favouring HearCheck; 95% CI0.4% to 8.2%; p=0.02). Conclusion Pure tone screen was better than HearCheck with respect to sensitivity but inferior with respect to specificity. As avoiding missed cases is arguably of greater importance for school entry screening, pure tone screen is probably preferable in this context. Study registration number Current controlled trials: ISRCTN61668996.

A content analysis of the representation of statins in the British newsprint media

Objective This study reviewed the news media coverage of statins, seeking to identify specific trends or differences in viewpoint between media outlets and examine common themes. Design The study is a content analysis of the frequency and content of the reporting of statins in a selection of the British newsprint media. It involved an assessment of the number, timing and thematic content of articles followed by a discourse analysis examining the underlying narratives. The sample was the output of four UK newspapers, covering a broad-spectrum readership, over a six month timeframe 1 October 2013 to 31 March 2014. Results A total of 67 articles included reference to statins. The majority (39, 58%) were reporting or responding to publication of a clinical study. The ratio of negative to positive coverage was greater than 2:1 overall. In the more politically right-leaning newspapers, 67% of coverage was predominantly negative (30/45 articles); 32% in the more left-leaning papers (7/22 articles). Common themes were the perceived ‘medicalisation’ of the population; the balance between lifestyle modification and medical treatments in the primary prevention of heart disease; side effects and effectiveness of statins; pharmaceutical sponsorship and implications for the reliability of evidence; trust between the public and government, institutions, research organisations and the medical profession. Conclusions Newsprint media coverage of statins was substantially influenced by the publication of national guidance and by coverage in the medical journals of clinical studies and comment. Statins received a predominantly negative portrayal, notably in the more right-leaning press. There were shared themes: concern about the balance between medication and lifestyle change in the primary prevention of heart disease; the adverse effects of treatment; and a questioning of the reliability of evidence from research institutions, scientists and clinicians in the light of their potential allegiances and funding.