Meta‐analysis: the glass eye of evidence‐based practice?

Meta-analysis was developed as a technique for combining the results of many different quantitative studies: it is often used to produce quantitative estimates of causal relations and/or association between variables. Meta-analysis is sometimes regarded as a central component of evidence-based practice. We draw attention to an incompatibility in the epistemology and methods of reasoning in quantitative meta-analysis and the epistemology and reasoning implicit in expert practice. We argue that this may be because the common perception of meta-analysis appeals to truth as correspondence; we suggest that rejecting the naive realism that underpins truth as correspondence allows meta-analysis to be understood in terms of truth as coherence. We can then develop an account of meta-analysis that does not depend upon reduction to a mathematical procedure but is an attempt to maximise coherence in beliefs about what works that is consistent with clinical reasoning in expert practice.     

‘The day of the soft towel?’: Comparison of the current bed‐bathing method with the Soft Towel bed‐bathing method

The impressions of 200 patients (both medical and surgical) and 200 nursing staff (registered, enrolled and trainee enrolled nurses) in relation to two bed-bathing methods were compared by means of questionnaires and semi-structured interviews. Data regarding costs were obtained from appropriate cost centre managers. The results of the study found the soft towel bed-bathing method to be more cost effective and provide more patient and nurse satisfaction than the current bed-bathing method.     

Is the “I‐Sign” in the 3‐Vessel and Trachea View a Valid Tool for Prenatal Diagnosis of d‐Transposition of the Great Arteries?

Prenatal diagnosis of d ‐transposition of the great arteries remains less frequent compared to other major congenital heart defects. In this study, we examined how often the 3‐vessel and trachea view was abnormal in a large series of prenatally diagnosed cases of d ‐transposition of the great arteries. We found that an abnormal 3‐vessel and trachea view in the shape of an “I” (“I‐sign”), which represents an anteriorly displaced aorta, was present in all fetuses with d ‐transposition of the great arteries when a 3‐vessel and trachea view was successfully obtained. Therefore we believe that the 3‐vessel and trachea view can be used to reliably detect d ‐transposition of the great arteries during prenatal sonography.     

Self‐harm: what's the problem? A literature review of the factors affecting attitudes towards self‐harm

People who have experienced self-harm report dissatisfaction with the care provided by statutory services. This review provides a critical exploration of the evidence examining the attitudes of healthcare professionals across both mental health and medical settings towards people who self-harm. It also explored in detail service users perceptions of care. A literature search conducted via electronic databases and cross-matching reference lists produced 19 papers that met the inclusion criteria. A thematic analysis of the literature indicated six key areas which contributed to the development of attitudes defined as positive or negative towards people who self-harm. Negative attitudes and experiences of care were associated with lack of education and training, the impact of differences in perceptions of health professionals' role and the influence of clinical culture as well as how self-harm was perceived as a health need. More positive attitudes were associated with a greater understanding of experiences of self-harm and improved training. However, the nature of care reported by service users indicates that there are still significant improvements needed to the attitudes in health settings to ensure they receive a high-quality service.     

Can B‐domain deletion alter the immunogenicity of recombinant factor VIII? A meta‐analysis of prospective clinical studies

See also Iorio A, Marcucci M, Makris M. Concentrate‐related inhibitor risk: is a difference always real? This issue, pp 2176–9. Summary. Background: As a result of the infrequency of inhibitors in previously treated patients (PTPs) with hemophilia A and the small size of available clinical studies, the immunogenicity of factor (F)VIII products has been difficult to assess. Objectives: A meta‐analysis of prospective clinical studies was conducted to test the hypothesis that de novo inhibitor incidence differs between PTPs receiving full‐length recombinant FVIII (FL‐rFVIII) and B‐domain deleted recombinant FVIII (BDD‐rFVIII). Methods: Prospective studies with data on inhibitors in PTPs receiving FL‐rFVIII or BDD‐rFVIII were sought using systematic methods including bibliographic database searches. Data were secured from published study reports and inquiries to investigators. Between‐group differences in inhibitor incidence rates were evaluated using mixed effects Cox regression. Results: Twenty‐nine studies with 3012 total PTPs were included. Patients were at risk of de novo inhibitor development for a median of 79 exposure days. A total of 35 de novo inhibitors were observed. The cumulative hazard for all de novo inhibitors was 1.25% with a 95% confidence interval (CI) of 0.63–1.88%. The corresponding rate for high‐titer de novo inhibitors [> 5 Bethesda units (BU)] was 0.29% (CI, 0.01–0.57%). Exposure to BDD‐rFVIII was associated with an increased risk of all de novo inhibitors (hazard ratio, 7.26; CI, 2.12–24.9; P = 0.0016) and of high‐titer de novo inhibitors (hazard ratio, 10.8; CI, 2.17–53.7; P = 0.0037), compared with FL‐rFVIII. Conclusions: This meta‐analysis of prospective clinical studies suggests that recombinant FVIII products may differ in immunogenicity.     

Drug‐induced prolongation of the QT interval: why the regulatory concern?

The views expressed in this paper are those of the author and do not necessarily represent the views or the opinions of Medicines Control Agency, other regulatory authorities or any of their advisory committees.     

Do selective COX‐2 inhibitors increase the risk of cerebrovascular events? A meta‐analysis of randomized controlled trials

ABSTRACT OBJECTIVES: To evaluate the risk of cerebrovascular events (CVEs) associated with selective cyclooxygenase-2 inhibitors (coxibs). METHOD: Systematic review and meta-analysis of randomized controlled trials (RCTs). A fixed-effect model was used to estimate the odds ratios (ORs) for risk of CVE associated with coxibs compared against placebo, non-selective non-steroidal anti-inflammatory drugs (NSAIDs) and other coxibs. RESULTS: Forty trials (88 116 patients) were included in the meta-analysis. The overall pooled OR for CVE for any coxib against placebo was 1.03 (95% CI: 0.71, 1.50). Comparing individual coxibs against placebo, we found that celecoxib, rofecoxib, etoricoxib and lumiracoxib were associated with higher CVE risks and valdecoxib was associated with a lower CVE risk, although there were no significant differences detected. There was also no significant difference in risk of CVE when comparing coxibs against any non-selective NSAIDs; the corresponding pooled OR was 0.86 (95% CI: 0.64, 1.16). CONCLUSION: On the basis of a detailed analysis of available RCTs, there does not appear to be any significant difference in risk of CVEs associated with coxibs when compared against placebo or non-selective NSAIDs. It is likely that the increased risk of thrombotic vascular events associated with coxibs is largely attributable to an increased risk of myocardial infarction, rather than CVEs.     

Mental health nurses' and allied health professionals' perceptions of the role of the Occupational Health Service in the management of work‐related stress: how do they self‐care?

Higher rates of stress-related sickness are found in health care professionals when compared with other sectors. The annual direct cost of absence to the National Health Service is ￡1.7 billion. Increased clinical demand, long hours, low staffing and a lack of support from colleagues and management are contributing to absenteeism, somatic complaints and mental health problems. Mental health work is inherently stressful and levels of work stress experienced by mental health nurses are especially high. The study investigated mental health nurses' and allied health professionals' (AHPs) awareness and knowledge of the service provided by the Occupational Health Service (OHS) and identified work-related stress and self-care strategies within these two groups. Nurses and AHP staff employed in mental health services in a Scottish healthboard area were invited to complete an anonymous questionnaire. Results demonstrated that staff found their contact with the OHS to be a positive experience. They considered direct patient care to be less stressful than the organizational constraints they work under, and they reported a lack of support from both their peer groups and management. There should be recognition of the increased stress that hospital-based nurses and AHPs experience. These areas should be scrutinized and reviewed further to support staff within these environments in accordance with organizational objectives.     

A question of competence? Re‐evaluating the roles of the nursing auxiliary and health care assistant in the NHS

This article draws from the first national sample survey evidence and detailed case studies of both the long-standing grade of Nursing Auxiliary/Assistant and of the new grade of 'Health Care Assistant/Support Worker' in the NHS. It argues for a fundamental re-evaluation of the real competencies of non-registered caregivers, and of their potential to progress into registered nurse training. The study demonstrates their real maturity, experience, competencies, roles and responsibilities, along with the extent to which they perceive themselves as 'substituting' for registered nursing staff. It is shown that many have been blocked from entering registered nurse training due to domestic and financial constraints. The rise of NVQ accreditation has now provided both the potential for a formal recognition of their experimental learning and also the means by which they might progress into registered nurse training or even along parallel--and more practice-orientated--lines. It is argued that registered nurses should welcome a more fluid and progressive role for these team members, since, failing such a welcome, managers will otherwise continue to 'undercut' registered staff with their 'cheaper' non-registered caregiving colleagues.     

Do case‐generic measures of queue performance for bypass surgery accurately reflect the waiting‐list experiences of those most urgent?

BACKGROUND: Queue performance is typically assessed using generic measures, which capture the queue in aggregate. The objective of this study was to examine whether case-generic measures of queue performance appropriately reflected the waiting-list experiences of those patients with greatest disease severity. METHODS: We examined the queue for isolated coronary artery bypass grafting (CABG) in Ontario between April 1993 and March 2000 using data obtained from the Cardiac Care Network. Our primary measure of queue performance was the proportion of patients who received their bypass surgery within their recommended maximum waiting times (%RMWTs) in any given month. We compared case-generic measures of queue performance to case-specific measures of queue performance stratified by urgency level. RESULTS: The queue was largely comprised of elective cases ranging from 73% (1993) to 57%(1999). Urgent patients comprised the minority of the queue ranging from 14% (1993) to 20% (1999). Case-generic month-to-month variations in the percentage of cases completed within RMWTs (an aggregated waiting list measure encompassing the characteristics of all patients in the queue) closely resembled the experiences of elective patients (R2 = 0.81), but conversely, bore little relationship to the waiting-list experiences of those most urgent (R2 = 0.15). INTERPRETATION: Case-generic measures of queue performance for bypass surgery in Ontario were not reflective of the waiting-list experiences of those most urgent. Our results reinforce the concept that urgency-specific waiting list monitoring systems are required to best evaluate and appropriately respond to fluctuations in queue performance.     

The success of precaution? Managing the risk of transfusion transmission of variant Creutzfeldt‐Jakob disease

The precautionary principle has emerged as an important new paradigm influencing decision making in the blood system. The principle has influenced decision making in several nations leading to the institution of policies to protect their blood supplies form variant Creutzfeldt-Jakob disease (vCJD). Increasingly evidence has emerged to support the institution of these policies, which were introduced in advance of clear evidence of risk. These vCJD decisions serve as an example of the successful application of precaution and provide lesions as to how the principle should be applied in future transfusion safety decisions.     

Does the clinical presentation and extent of venous thrombosis predict likelihood and type of recurrence? A patient‐level meta‐analysis

Summary. Aim: To determine if the mode of presentation of venous thromboembolism (VTE), as deep vein thrombosis (DVT) or pulmonary embolism (PE), predicts the likelihood and type of recurrence. Methods: We carried out a patient‐level meta‐analysis of seven prospective studies in patients with a first VTE who were followed after anticoagulation was stopped. We used Kaplan‐Meier analysis to determine the cumulative incidence of recurrent VTE according to mode of presentation, and multivariable Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for mode of and extent of DVT as potential risk factors for recurrence. Results: The 5‐year cumulative rate of recurrent VTE in 2554 patients was 22.6%. In 869 (36.1%) patients with PE, the 5‐year rate of any recurrence (DVT or PE) was 22.0%, and recurrence as PE was 10.6%. In 1365 patients with proximal DVT, the 5‐year recurrence rate was 26.4%, and recurrence with PE was 3.6%. The risk of recurrence as PE was 3.1‐fold greater in patients presenting with symptomatic PE than in patients with proximal DVT (HR, 3.1; 95% CI, 1.9–5.1). Patients with proximal DVT had a 4.8‐fold higher cumulative recurrence rate than those with distal DVT (HR, 4.8; 95% CI, 2.1–11.0). Conclusion: Whilst DVT and PE are manifestations of the same disease, the phenotypic expression is predetermined. Patients presenting with PE are three times more likely to suffer recurrence as PE than patients presenting with DVT. Patients presenting with calf DVT are at low risk of recurrence and at low risk of recurrence as PE.     

Pacemaker‐mediated tachycardia in a dual‐lead CRT‐D: What is the mechanism?

A 73‐year‐old gentleman with dilated cardiomyopathy, left bundle branch block and a left ventricular (LV) ejection fraction of 20% was implanted with two LV leads in a tri‐ventricular cardiac resynchronisation therapy defibrillator (CRT‐D) trial. As a part of the trial he was programmed with fusion‐based CRT therapy with dual LV lead only pacing. The patient presented to local heart failure service 12 years after implant, after a positive response to CRT therapy, with increase in fatigue, shortness of breath and bilateral pitting oedema. The patient sent a remote monitoring transmission that suggested loss of capture on one of the LV leads. This coupled with atrial ectopics was producing a high burden of pacemaker‐mediated tachycardia (PMT) that was not seen when both LV leads had been capturing. What is the mechanism for this? Dual LV‐lead tri‐ventricular leads have been shown to have variable improvements in CRT response but with an increased complexity of implant procedure. This is the first case report of PMT‐induced heart failure exacerbation in a tri‐ventricular device following loss of LV capture of one lead.