Ontario health technology assessment series
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Ont Health Technol Assess Ser · Jan 2010
Kidney and liver organ transplantation in persons with human immunodeficiency virus: An Evidence-Based Analysis.
The objective of this analysis is to determine the effectiveness of solid organ transplantation in persons with end stage organ failure (ESOF) and human immunodeficiency virus (HIV+) ⋯ No direct evidence comparing an HIV+ cohort undergoing transplantation with the same not undergoing transplantation (wait list) was found in the literature search. The results of this review are reported for the following comparison cohorts undergoing transplantation: I) KIDNEY TRANSPLANTATION: HIV+ cohort compared with HIV- cohortII) LIVER TRANSPLANTATION: HIV+ cohort compared with HIV- negative cohortIII) LIVER TRANSPLANTATION: HIV+ HCV+ (co-infected) cohort compared with HCV+ (mono-infected) cohort KIDNEY TRANSPLANTATION: HIV+ VS. HIV#ENTITYSTARTX02212; Based on a pooled HIV+ cohort sample size of 285 patients across four studies, the risk of death after kidney transplantation in an HIV+ cohort does not differ to that of an HIV- cohort [hazard ratio (HR): 0.90; 95% CI: 0.36, 2.23]. The quality of evidence supporting this outcome is very low. Death censored graft survival was reported in one study with an HIV+ cohort sample size of 100, and was statistically significantly different (p=.03) to that in the HIV- cohort (n=36,492). However, the quality of evidence supporting this outcome was determined to be very low. There was also uncertainty in the rate of return to dialysis after kidney transplantation in both the HIV+ and HIV- groups and the effect, if any, this may have on patient survival. Because of the very low quality evidence rating, the effect of kidney transplantation on HIV-disease progression is uncertain. The rate of acute graft rejection was determined using the data from one study. There was a nonsignificant difference between the HIV+ and HIV- cohorts (OR 0.13; 95% CI: 0.01, 2.64), although again, because of very low quality evidence there is uncertainty in this estimate of effect. LIVER TRANSPLANTATION: HIV+ VS. HIV#ENTITYSTARTX02212; Based on a combined HIV+ cohort sample size of 198 patient across five studies, the risk of death after liver transplantation in an HIV+ cohort (with at least 50% of the cohort co-infected with HCV+) is statistically significantly 64% greater compared with an HIV- cohort (HR: 1.64; 95% CI: 1.32, 2.02). The quality of evidence supporting this outcome is very low. Death censored graft survival was reported for an HIV+ cohort in one study (n=11) however the DCGS rate of the contemporaneous control HIV- cohort was not reported. Because of sparse data the quality of evidence supporting this outcome is very low indicating death censored graft survival is uncertain. Both the CD4+ T-cell count and HIV viral load appear controlled post transplant with an incidence of opportunistic infection of 20.5%. However, the quality of this evidence for these outcomes is very low indicating uncertainty in these effects. Similarly, because of very low quality evidence there is uncertainty in the rate of acute graft rejection among both the HIV+ and HIV- groups LIVER TRANSPLANTATION: HIV+/HCV+ VS. HCV+ Based on a combined HIV+/HCV+ cohort sample size of 156 from seven studies, the risk of death after liver transplantation is significantly greater (2.8 fold) in a co-infected cohort compared with an HCV+ mono-infected cohort (HR: 2.81; 95% CI: 1.47, 5.37). The quality of evidence supporting this outcome is very low. Death censored graft survival evidence was not available. Regarding disease progression, based on a combined sample size of 71 persons in the co-infected cohort, the CD4+ T-cell count and HIV viral load appear controlled post transplant; however, again the quality of evidence supporting this outcome is very low. The rate of opportunistic infection in the co-infected cohort was 7.2%. The quality of evidence supporting this estimate is very low, indicating uncertainty in these estimates of effect. Based on a combined HIV+/HCV+ cohort (n=57) the rate of acute graft rejection does not differ to that of an HCV+ mono-infected cohort (OR: 0.88; 95% CI: 0.44, 1.76). Also based on a combined HIV+/HCV+ cohort (n=83), the rate of HCV+ recurrence does not differ to that of an HCV+ mono-infected cohort (OR: 0.66; 95% CI: 0.27, 1.59). In both cases, the quality of the supporting evidence was very low. Overall, because of very low quality evidence there is uncertainty in the effect of kidney or liver transplantation in HIV+ persons with end stage organ failure compared with those not infected with HIV. Examining the economics of this issue, the cost of kidney and liver transplants in an HIV+ patient population are, on average, 56K and 147K per case, based on both Canadian and American experiences.
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Ont Health Technol Assess Ser · Jan 2010
Neuroimaging for the evaluation of chronic headaches: an evidence-based analysis.
The objectives of this evidence based review are: i) To determine the effectiveness of computed tomography (CT) and magnetic resonance imaging (MRI) scans in the evaluation of persons with a chronic headache and a normal neurological examination.ii) To determine the comparative effectiveness of CT and MRI scans for detecting significant intracranial abnormalities in persons with chronic headache and a normal neurological exam.iii) To determine the budget impact of CT and MRI scans for persons with a chronic headache and a normal neurological exam. ⋯ One systematic review, 1 small RCT, and 1 observational study met the inclusion and exclusion criteria. The systematic review completed by Detsky, et al. reported the likelihood ratios of specific clinical variables to predict significant intracranial abnormalities. The RCT completed by Howard et al., evaluated whether neuroimaging persons with chronic headache increased or reduced patient anxiety. The prospective observational study by Sempere et al., provided evidence for the pre-test probability of intracranial abnormalities in persons with chronic headache as well as minimal data on the comparative effectiveness of CT and MRI to detect intracranial abnormalities. OUTCOME 1: PRE-TEST PROBABILITY. The pre-test probability is usually related to the prevalence of the disease and can be adjusted depending on the characteristics of the population. The study by Sempere et al. determined the pre-test probability (prevalence) of significant intracranial abnormalities in persons with chronic headaches defined as headache experienced for at least a 4 week duration with a normal neurological exam. There is a pre-test probability of 0.9% (95% CI 0.5, 1.4) in persons with chronic headache and normal neurological exam. The highest pre-test probability of 5 found in persons with cluster headaches. The second highest, that of 3.7, was reported in persons with indeterminate type headache. There was a 0.75% rate of incidental findings. LIKELIHOOD RATIOS FOR DETECTING A SIGNIFICANT ABNORMALITY: Clinical findings from the history and physical may be used as screening test to predict abnormalities on neuroimaging. The extent to which the clinical variable may be a good predictive variable can be captured by reporting its likelihood ratio. The likelihood ratio provides an estimate of how much a test result will change the odds of having a disease or condition. The positive likelihood ratio (LR+) tells you how much the odds of having the disease increases when a test is positive. The negative likelihood ratio (LR-) tells you how much the odds of having the disease decreases when the test is negative. Detsky et al., determined the likelihood ratio for specific clinical variable from 11 studies. There were 4 clinical variables with both statistically significant positive and negative likelihood ratios. These included: abnormal neurological exam (LR+ 5.3, LR- 0.72), undefined headache (LR+ 3.8, LR- 0.66), headache aggravated by exertion or valsalva (LR+ 2.3, LR- 0.70), and headache with vomiting (LR+ 1.8, and LR- 0.47). There were two clinical variables with a statistically significant positive likelihood ratio and non significant negative likelihood ratio. These included: cluster-type headache (LR+ 11, LR- 0.95), and headache with aura (LR+ 12.9, LR- 0.52). Finally, there were 8 clinical variables with both statistically non significant positive and negative likelihood ratios. These included: headache with focal symptoms, new onset headache, quick onset headache, worsening headache, male gender, headache with nausea, increased headache severity, and migraine type headache. OUTCOME 2: RELIEF FROM ANXIETY Howard et al. completed an RCT of 150 persons to determine if neuroimaging for headaches was anxiolytic or anxiogenic. Persons were randomized to receiving either an MRI scan or no scan for investigation of their headache. The study population was stratified into those persons with a Hospital Anxiety and Depression scale (HADS) > 11 (the high anxiety and depression group) and those < 11 (the low anxiety and depression) so that there were 4 groups: Group 1: High anxiety and depression, no scan group Group 2: High anxiety and depression, scan group Group 3: Low anxiety and depression, no scan group Group 4: Low anxiety and depression, scan group ANXIETY: There was no evidence for any overall reduction in anxiety at 1 year as measured by a visual analogue scale of 'level of worry' when analysed by whether the person received a scan or not. Similarly, there was no interaction between anxiety and depression status and whether a scan was offered or not on patient anxiety. Anxiety did not decrease at 1 year to any statistically significant degree in the high anxiety and depression group (HADS positive) compared with the low anxiety and depression group (HADS negative). There are serious methodological limitations in this study design which may have contributed to these negative results. First, when considering the comparison of 'scan' vs. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2010
Positron emission tomography for the assessment of myocardial viability: an evidence-based analysis.
In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability, an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients undergoing viability assessment. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies that can be used for the assessment of myocardial viability: positron emission tomography, cardiac magnetic resonance imaging, dobutamine echocardiography, and dobutamine echocardiography with contrast, and single photon emission computed tomography.A 2005 review conducted by MAS determined that positron emission tomography was more sensitivity than dobutamine echocardiography and single photon emission tomography and dominated the other imaging modalities from a cost-effective standpoint. However, there was inadequate evidence to compare positron emission tomography and cardiac magnetic resonance imaging. Thus, this report focuses on this comparison only. For both technologies, an economic analysis was also completed.The Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.htmlPOSITRON EMISSION TOMOGRAPHY FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: An Evidence-Based AnalysisMAGNETIC RESONANCE IMAGING FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: An Evidence-Based Analysis ⋯ Positron emission tomography (PET) is a nuclear medicine technique used to image tissues based on the distinct ways in which normal and abnormal tissues metabolize positron-emitting radionuclides. Radionuclides are radioactive analogs of common physiological substrates such as sugars, amino acids, and free fatty acids that are used by the body. The only licensed radionuclide used in PET imaging for viability assessment is F-18 fluorodeoxyglucose (FDG). During a PET scan, the radionuclides are injected into the body and as they decay, they emit positively charged particles (positrons) that travel several millimetres into tissue and collide with orbiting electrons. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2010
Endovascular laser therapy for varicose veins: an evidence-based analysis.
The objective of the MAS evidence review was to conduct a systematic review of the available evidence on the safety, effectiveness, durability and cost-effectiveness of endovascular laser therapy (ELT) for the treatment of primary symptomatic varicose veins (VV). ⋯ The MAS evidence search identified 14 systematic reviews, 29 cohort studies on safety and effectiveness, four cost studies and 12 randomized controlled trials involving ELT, six of these comparing endovascular laser with surgical ligation and saphenous vein stripping. Since 2007, 22 cohort studies involving 10,883 patients undergoing ELT of the great saphenous vein (GSV) have been published. Imaging defined treatment effectiveness of mean vein closure rates were reported to be greater than 90% (range 93%- 99%) at short term follow-up. Longer than one year follow-up was reported in five studies with life table analysis performed in four but the follow up was still limited at three and four years. The overall pooled major adverse event rate, including DVT, PE, skin burns or nerve damage events extracted from these studies, was 0.63% (69/10,883). The overall level of evidence of randomized trials comparing ELT with surgical ligation and vein stripping (n= 6) was graded as moderate to high. Recovery after treatment was significantly quicker after ELT (return to work median number of days, 4 vs. 17; p= .005). Major adverse events occurring after surgery were higher [(1.8% (n=4) vs. 0.4% (n = 1) 1 but not significantly. Treatment effectiveness as measured by imaging vein absence or closure, symptom relief or quality of life similar in the two treatment groups and both treatments resulted in statistically significantly improvements in these outcomes. Recurrence was low after both treatments at follow up but neovascularization (growth of new vessels, a key predictor of long term recurrence was significantly more common (18% vs. 1%; p = .001) after surgery. Although patient satisfaction was reported to be high (>80%) with both treatments, patient preferences evaluated through recruitment process, physician reports and consumer groups were strongly in favour of ELT. For patients minimal complications, quick recovery and dependability of outpatient scheduling were key considerations. As clinical effectiveness of the two treatments was similar, a cost-analysis was performed to compare differences in resources and costs between the two procedures. A budget impact analysis for introducing ELT as an insured service was also performed. The average case cost (based on Ontario hospital costs and medical resources) for surgical vein stripping was estimated to be $1,799. Because of the uncertainties with resources associated with ELT, in addition to the device related costs, hospital costs were varied and assumed to be the same as or less than (40%) those for surgery resulting in an average ELT case cost of $2,025 or $1,602. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2010
Stress echocardiography for the diagnosis of coronary artery disease: an evidence-based analysis.
In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website).The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas">www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.htmlSINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY WITH CONTRAST FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based Analysis64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based AnalysisCARDIAC MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisPease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website:POSITRON EMISSION TOMOGRAPHY FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: An Evidence-Based AnalysisMAGNETIC RESONANCE IMAGING FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: an Evidence-Based AnalysisThe Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled:The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 OBJECTIVE: The objective of the analysis is to determine the diagnostic accuracy of stress echocardiography (ECHO) in the diagnosis of patients with suspected coronary artery disease (CAD) compared to coronary angiography (CA). STRESS ECHOCARDIOGRAPHY: Stress ECHO is a non-invasive technology that images the heart using ultrasound. It is one of the most commonly employed imaging techniques for investigating a variety of cardiac abnormalities in both community and hospital settings. A complete ECHO exam includes M-mode, 2-dimensional (2-D) images and Doppler imaging. In order to diagnosis CAD and assess whether myocardial ischemia is present, images obtained at rest are compared to those obtained during or immediately after stress. The most commonly used agents used to induce stress are exercise and pharmacological agents such as dobutamine and dipyridamole. The hallmark of stress-induced myocardial ischemia is worsening of wall motion abnormalities or the development of new wall motion abnormalities. A major challenge for stress ECHO is that the interpretation of wall motion contractility and function is subjective. This leads to inter-observer variability and reduced reproducibility. Further, it is estimated that approximately 30% of patients have sub-optimal stress ECHO exams. To overcome this limitation, contrast agents for LV opacification have been developed. Although stress ECHO is a relatively easy to use technology that poses only a low risk of adverse events compared to other imaging technologies, it may potentially be overused and/or misused in CAD diagnosis. Several recent advances have been made focusing on quantitative methods for assessment, improved image quality and enhanced portability, however, evidence on the effectiveness and clinical utility of these enhancements is limited. EVIDENCE-BASED ANALYSIS: ⋯ Given the vast amount of published literature on stress ECHO, it was decided to focus on the studies contained in the comprehensive 2007 review by Heijenbrok-Kal et al. (1) as a basis for the MAS evidence-based analysis. In applying our inclusion and exclusion criteria, 105 observational studies containing information on 13,035 patients were included. Six studies examined stress ECHO with adenosine, 26 with dipyridamole and 77 with dobutamine, the latter being the most commonly used pharmacological stress ECHO agent in Ontario. A further 18 studies employed exercise as the stressor.() The prevalence of CAD ranged from 19% to 94% with a mean estimated prevalence of 70%. Based on the results of these studies the following conclusions were made: Based on the available evidence, stress ECHO is a useful imaging modality for the diagnosis of CAD in patients with suspected disease. The overall pooled sensitivity is 0.80 (95% CI: 0.77 - 0.82) and the pooled specificity is 0.84 (95% CI: 0.82 - 0.87) using CA as the reference standard. The AUC derived from the sROC curve is 0.895 and the DOR is 20.64.For pharmacological stress, the pooled sensitivity is 0.79 (95% CI: 0.71 - 0.87) and the pooled specificity is 0.85 (95% CI: 0.83 - 0.88). When exercise is employed as the stress agent, the pooled sensitivity is 0.81 (95% CI: 0.76- 0.86) and the pooled specificity is 0.79 (95% CI: 0.71 - 0.87). Although pharmacological stress and exercise stress would be indicated for different patient populations based on ability to exercise there were no significant differences in sensitivity and specificity.Based on clinical experts, diagnostic accuracy on stress ECHO depends on the patient population, the expertise of the interpreter and the quality of the image.