Ontario health technology assessment series
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Ont Health Technol Assess Ser · Jan 2009
Intrastromal corneal ring implants for corneal thinning disorders: an evidence-based analysis.
The purpose of this project was to determine the role of corneal implants in the management of corneal thinning disease conditions. An evidence-based review was conducted to determine the safety, effectiveness and durability of corneal implants for the management of corneal thinning disorders. The evolving directions of research in this area were also reviewed. SUBJECT OF THE EVIDENCE-BASED ANALYSIS: The primary treatment objectives for corneal implants are to normalize corneal surface topography, improve contact lens tolerability, and restore visual acuity in order to delay or defer the need for corneal transplant. Implant placement is a minimally invasive procedure that is purported to be safe and effective. The procedure is also claimed to be adjustable, reversible, and both eyes can be treated at the same time. Further, implants do not limit the performance of subsequent surgical approaches or interfere with corneal transplant. The evidence for these claims is the focus of this review. The specific research questions for the evidence review were as follows: SafetyCorneal Surface Topographic Effects:Effects on corneal surface remodellingImpact of these changes on subsequent interventions, particularly corneal transplantation (penetrating keratoplasty [PKP])Visual AcuityRefractive OutcomesVISUAL QUALITY (SYMPTOMS): such as contrast vision or decreased visual symptoms (halos, fluctuating vision)Contact lens toleranceFunctional visual rehabilitation and quality of lifePatient satisfaction:Disease Process:Impact on corneal thinning processEffect on delaying or deferring the need for corneal transplantation ⋯ In the MAS evidence review on intrastromal corneal ring implants, 66 reports were identified on the use of implants for management of corneal thinning disorders. Reports varied according to their primary clinical indication, type of corneal implant, and whether or not secondary procedures were used in conjunction with the implants. Implants were reported to manage post LASIK thinning and/or uncorrected refractive error and were also reported as an adjunctive intervention both during and after corneal transplant to manage recurrent thinning and/or uncorrected refractive error. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2009
Point-of-Care International Normalized Ratio (INR) Monitoring Devices for Patients on Long-term Oral Anticoagulation Therapy: An Evidence-Based Analysis.
SUBJECT OF THE EVIDENCE-BASED ANALYSIS: The purpose of this evidence based analysis report is to examine the safety and effectiveness of point-of-care (POC) international normalized ratio (INR) monitoring devices for patients on long-term oral anticoagulation therapy (OAT). ⋯ There was no statistically significant difference in the number of major hemorrhagic events between patients managed with POC INR monitoring devices and patients managed with standard laboratory testing (OR =0.74; 95% CI: 0.52- 1.04). This difference was non-significant for all POC strategies (PSM, PST, health care practitioner). Patients managed with POC INR monitoring devices had significantly fewer thromboembolic events than usual care patients (OR =0.52; 95% CI: 0.37 - 0.74). When divided by POC strategy, PSM resulted in significantly fewer thromboembolic events than usual care (OR =0.46.; 95% CI: 0.29 - 0.72). The observed difference in thromboembolic events for PSM remained significant when the analysis was limited to major thromboembolic events (OR =0.40; 95% CI: 0.17 - 0.93), but was non-significant when the analysis was limited to minor thromboembolic events (OR =0.73; 95% CI: 0.08 - 7.01). PST and GP/Nurse strategies did not result in significant differences in thromboembolic events, however there were only a limited number of studies examining these interventions. No statistically significant difference was observed in the number of deaths between POC intervention and usual care control groups (OR =0.67; 95% CI: 0.41 - 1.10). This difference was non-significant for all POC strategies. Only one study reported on survival with 10-year survival rate of 76.1% in the usual care control group compared to 84.5% in the PSM group (P=0.05). ES Table 1:Summary Results of Meta-Analyses of Major Complications and Deaths in POC INR Monitoring StudiesEventNo. of trials(patients)OR(M-H, Random Effects)95% CIMajor Haemorrhages16 (5057)0.740.52 to 1.04Thromboembolic events16 (5057)0.520.37 to 0.74Deaths11 (2906)0.670.41 to 1.10 PATIENT SATISFACTION AND QUALITY OF LIFE: Quality of life measures were reported in eight studies comparing POC INR monitoring to standard laboratory testing using a variety of measurement tools. It was thus not possible to calculate a quantitative summary measure. The majority of studies reported favourable impacts of POC INR monitoring on QoL and found better treatment satisfaction with POC monitoring. Results from a pre-analysis patient and caregiver focus group conducted in Ontario also indicated improved patient QoL with POC monitoring. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2009
Behavioural interventions for type 2 diabetes: an evidence-based analysis.
In June 2008, the Medical Advisory Secretariat began work on the Diabetes Strategy Evidence Project, an evidence-based review of the literature surrounding strategies for successful management and treatment of diabetes. This project came about when the Health System Strategy Division at the Ministry of Health and Long-Term Care subsequently asked the secretariat to provide an evidentiary platform for the Ministry's newly released Diabetes Strategy.After an initial review of the strategy and consultation with experts, the secretariat identified five key areas in which evidence was needed. Evidence-based analyses have been prepared for each of these five areas: insulin pumps, behavioural interventions, bariatric surgery, home telemonitoring, and community based care. For each area, an economic analysis was completed where appropriate and is described in a separate report.To review these titles within the Diabetes Strategy Evidence series, please visit the Medical Advisory Secretariat Web site, http://www.health.gov.on.ca/english/providers/program/mas/mas_about.html,DIABETES STRATEGY EVIDENCE PLATFORM: Summary of Evidence-Based AnalysesContinuous Subcutaneous Insulin Infusion Pumps for Type 1 and Type 2 Adult Diabetics: An Evidence-Based Analysis Behavioural Interventions for Type 2 Diabetes: An Evidence-Based Analysis BARIATRIC SURGERY FOR PEOPLE WITH DIABETES AND MORBID OBESITY: An Evidence-Based Summary Community-Based Care for the Management of Type 2 Diabetes: An Evidence-Based Analysis Home Telemonitoring for Type 2 Diabetes: An Evidence-Based Analysis Application of the Ontario Diabetes Economic Model (ODEM) to Determine the Cost-effectiveness and Budget Impact of Selected Type 2 Diabetes Interventions in Ontario ⋯ The search identified 638 citations published between 1996 and August 2008, of which 12 met the inclusion criteria and one was a meta-analysis (Gary et al. 2003). The remaining 11 studies were RCTs (9 were used in the meta-analysis) and only one was defined as small (total sample size N=47). SUMMARY OF PARTICIPANT DEMOGRAPHICS ACROSS STUDIES: A total of 2,549 participants were included in the 11 identified studies. The mean age of participants reported was approximately 58 years and the mean duration of diabetes was approximately 6 years. Most studies reported gender with a mean percentage of females of approximately 67%. Of the eleven studies, two focused only on women and four included only Hispanic individuals. All studies evaluated type 2 diabetes patients exclusively. STUDY CHARACTERISTICS: The studies were conducted between 2002 and 2008. Approximately six of 11 studies were carried out within the USA, with the remaining studies conducted in the UK, Sweden, and Israel (sample size ranged from 47 to 824 participants). The quality of the studies ranged from moderate to low with four of the studies being of moderate quality and the remaining seven of low quality (based on the Consort Checklist). Differences in quality were mainly due to methodological issues such as inadequate description of randomization, sample size calculation allocation concealment, blinding and uncertainty of the use of intention-to-treat (ITT) analysis. Patients were recruited from several settings: six studies from primary or general medical practices, three studies from the community (e.g. via advertisements), and two from outpatient diabetes clinics. A usual care control group was reported in nine of 11 of the studies and two studies reported some type of minimal diabetes care in addition to usual care for the control group. INTERVENTION CHARACTERISTICS: All of the interventions examined in the studies were mapped to the 2007 Self-management Mapping Guide. The interventions most often focused on problem solving, goal setting and encouraging participants to engage in activities that protect and promote health (e.g. modifying behaviour, change in diet, and increase physical activity). All of the studies examined comprehensive interventions targeted at least two self-care topics (e.g. diet, physical activity, blood glucose monitoring, foot care, etc.). Despite the homogeneity in the aims of the interventions, there was substantial clinical heterogeneity in other intervention characteristics such as duration, intensity, setting, mode of delivery (group vs. individual), interventionist, and outcomes of interest (discussed below). DURATION, INTENSITY AND MODE OF DELIVERY: Intervention durations ranged from 2 days to 1 year, with many falling into the range of 6 to 10 weeks. The rest of the interventions fell into categories of ≤ 2 weeks (2 studies), 6 months (2 studies), or 1 year (3 studies). Intensity of the interventions varied widely from 6 hours over 2 days, to 52 hours over 1 year; however, the majority consisted of interventions of 6 to 15 hours. Both individual and group sessions were used to deliver interventions. Group counselling was used in five studies as a mode of instruction, three studies used both individual and group sessions, and one study used individual sessions as its sole mode of instruction. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2009
Fecal occult blood test for colorectal cancer screening: an evidence-based analysis.
The colorectal cancer (CRC) screening project was undertaken by the Medical Advisory Secretariat (MAS) in collaboration with the Cancer Care Ontario (CCO).In November 2007, the Ontario Health Technology Advisory Committee (OHTAC) MAS to conduct an evidence-based analysis of the available data with respect to colorectal cancer diagnosis and prevention. The general purpose of the project was to investigate the effectiveness, cost effectiveness, and safety of the various methods and techniques used for colorectal cancer screening in average risk people, 50 years of age and older.The options currently offered for colorectal cancer screening were reviewed and five technologies were selected for review:Computed tomographic (CT) colonographyMagnetic resonance (MR) colonographyWireless capsule endoscopy (PillCam Colon)Fecal occult blood test (FOBT)Flexible sigmoidoscopyIn this review, colonoscopy was considered as the "gold standard" technique by which the effectiveness of all other modalities could be evaluated. An economic analysis was also conducted to determine cost-effectiveness of different screening modalities.Evidence-based analyses have been prepared for each of these technologies, as well as summary document that includes an economic analysis, all of which are presented at the MAS Web site: http://www.health.gov.on.ca/english/providers/program/mas/tech/techmn.html ⋯ SINGLE-TEST STUDIES: There is limited direct/indirect evidence that iFOBT has sensitivity/specificity superior to that of unrehydrated gFOBT for CRC detection: sensitivity for gFOBT:13% and 25%pooled iFOBT sensitivity:81%There is evidence that iFOBT and gFOBT have lower sensitivities for adenoma detection than for CRC detection: sensitivity for rehydrated gFOBT22%pooled iFOBT sensitivity28% REPEATED-TEST STUDIES: No trials have examined CRC mortality outcomes after repeated testing of iFOBT. Two RCTs from the United Kingdom and Denmark showed significant reduction in CRC mortality using unrehydrated gFOBT biennially Relative risk reductions of 13% (UK trial) and 16% (Danish trial); absolute difference of 0.1% (UK trial) and 0.2% (Danish trial).No significant reduction in overall mortalityInterval cancers (CRC that develop in the intervals between routine screening) UNITED KINGDOM TRIAL: 236 CRCs detected by positive test, 236 interval CRCs after negative testDANISH TRIAL: 120 CRCs detected by positive test, 146 interval CRCs after negative testUnrehydrated gFOBT has low sensitivity for CRC detection (45% in the UK trial and 54% in the Danish trial). true positive rate50% (United Kingdom and Danish RCTs)false positive rate5%-10%true negative rate90%-95% (from observational studies as RCTs did not report specificity)false negative rate50%ES Table 1:Guaiac FOBT - GRADE Quality of Evidence for InterventionsOutcomeDesignQualityConsistencyDirectnessOverall QualityCRCMortalityRCTDanishN = 137,485United KingdomN = 152,850No seriouslimitationsYes (RR reduction in 2 trials13% and 16%; absolutedifference 0.1% and 0.2%respectively).Age rangeDanish and UnitedKingdom study 45-75yearsHighCRC indicates colorectal cancer; FOBT, fecal occult blood test; GRADE, Grading of Recommendations Assessment, Development and Evaluation; RCT, randomized controlled trial.*Unlikely to be an important uncertainty.ES Table 2:GRADE Quality of Evidence for Diagnostic Tests: Implications of Testing Focusing on AccuracyNew Test and Reference TestPutative BenefitDiagnostic AccuracyPatient Outcomes and Expected Impact on ManagementSensitivitySpecificityTrue PositiveTrue NegativeFalse PositiveFalse NegativePresumed Influence on Outcomes Important to PatientsiFOBT and ColonoscopySimple, non-invasiveLessLessBenefit from diagnosis and treatment after confirmatory colonoscopySmall risk of bowel perforation during colonoscopyBenefit of reassuranceAnxiety/worry leading up to confirmatory colonoscopySmall risk of bowel perforation during confirmatory colonoscopyDetriment from delayed diagnosisDirectness of Evidence (Test Results) for Outcomes Important to PatientsSome uncertainty (until after confirmatory colonoscopy)No UncertaintyUncertaintyUncertaintyFOBT indicates fecal occult blood test; GRADE, Grading of Recommendations Assessment, Development and Evaluation.Es Table 3:Immunochemical FOBT - GRADE Quality of Evidence for Diagnostic StudiesNo. ofStudiesDesignLimitationsIndirectnessInconsistencyImprecise dataQuality6Diagnostic cohort (single test)(reference standard for positive and negative iFOBT results was colonoscopy)No serious limitationsTP Some uncertaintyTN No uncertaintyFP UncertaintyFN UncertaintyTP rate = 69%TN rate = 94%FP rate = 6%FN rate = 30%(from direct comparison study)Diagnostic cohort iFOBT sensitivities: 50% to 90%High I(2)in pooled sensitivity and specificityWide range in confidence intervals in direct comparison studyLow*FN indicates false negative; FOBT, fecal occult blood test; FP, false positive; Development and Evaluation; TN, true negative; TP, true positive.*Uncertainty until after confirmatory colonoscopy†Stress/worry for patient until confirmatory colonoscopy‡Detrimental effects due to delayed diagnosis.§For these 3 reasons, downgrade quality from High to Moderate.║For these 3 reasons, downgrade quality from Moderate to Low. CONSIDERATIONS FOR THE ONTARIO HEALTH SYSTEM: Executive Summary Table 4 shows the potential system pressures and benefit/risk analysis for the use of FOBT and colonoscopy to screen for CRC in average-risk adults, ages 50 and over in Ontario. Es Table 4:Summary of Potential System Pressures for FOBT ScreeningCriterionColonoscopyFOBTPrimarily prevent or detect cancer?Prevent and detectDetectFrequency of screeningEvery 10 yearsMust repeat at regular intervalsEvery 2 yearsMust repeat at regular intervalsLevel of evidenceObservational studiesRCTsBenefitsUsed as gold standard in studiesINTERVENTION GRADE QUALITY: High (gFOBT)DIAGNOSTIC GRADE QUALITY: Low (iFOBT)No RCTs examining the effectiveness of repeated iFOBT on CRC mortality reduction were identifiedLimited direct/indirect evidence that iFOBT has superior sensitivity/specificity to unrehydrated gFOBT for detection of CRCRisks0.1% risk of serious bleeding and perforation requiring surgery0.3% risk of serious complications (stroke/bleeding requiring hospitalization/ myocardial infarction)High interval cancer rateThe small benefit in CRC mortality reduction (absolute difference 0.1% to 0.2%) also coincides with a 0.3% risk of serious complications.Preparation requirementsNo food 1 day prior to examOffice/hospital visitComplete bowel preparationSedationEliminate citrus fruit and juices and vitamin C from diet for 3 days prior to/during stool collection.Person applies 2 samples per bowel movement (each occurring on 3 different days) onto test areas of FOBT cards.Resources required for screening asymptomatic, average-risk adults ≥ 50 yearsIncreased demand for colonoscopies and colonoscopists or nurses who perform colonoscopies. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2009
Fenestrated endovascular grafts for the repair of juxtarenal aortic aneurysms: an evidence-based analysis.
Endovascular repair of abdominal aortic aneurysm (AAA) allows the exclusion of the dilated aneurismal segment of the aorta from the systematic circulation. The procedure requires, however, that the endograft extends to the healthy parts of the aorta above and below the aneurysm, yet the neck of a juxtarenal aortic aneurysm (JRA) is too short for a standard endovascular repair. Fenestrated endovascular aortic repair (f-EVAR) provides a solution to overcome this problem by enabling the continuation of blood flow to the renal and visceral arteries through holes or 'fenestrations' in the graft. These fenestrations are designed to match the ostial diameter of the renal and visceral arteries.There are three varieties fenestration, small, large, and scallop, and their location needs to be customized to fit the anatomy of the patient. If the device is not properly designed, if the alignment is inaccurate, or if the catheterization of the visceral arteries is not possible, the procedure may fail. In such cases, conversion to open surgery may become the only option as fenestrated endografts are not retrievable.It is recommended that a stent be placed within each small fenestration to the target artery to prevent shuttering of the artery or occlusion. Many authors have noted an increased risk of vessel occlusion in unstented fenestrations and scallops.Once placed in a patient, life-long follow-up at regular intervals is necessary to ensure the graft remains in its intended location, and that the components have adequate overlap. Should the need arise, routine follow-up allows the performance of timely and appropriate intervention through detection of events that could impact the long-term outcomes. ⋯ f-EVAR Studies versus OSR StudiesTechniqueNumber ofPatientsMean Age(Range), YearsAneurysm Diameter(Range),mmMean Duration ofFollow-up, Yearsf-EVAR(5 studies)27474 (72-75)63 (59-68)9.4-25.8OSR(7 studies)856:JRA: 675SRA: 136TAA: 4572 (67-78)62 (50-70)1-48JRA, Juxtarenal aortic aneurysm; SRA, Suprarenal aortic aneurysm; TAA, Thoracic aortic aneurysm MORTALITY OUTCOMES: The pooled estimate for 30-day mortality was 1.8% among the f-EVAR studies and 3.1% among the OSR studies that reported data for the repair of JRA separately. The pooled estimate for late mortality was 12.8% among the f-EVAR studies and 23.7% among the OSR studies that reported data for JRA separately. VISCERAL ARTERY EVENTS REPORTED IN F#ENTITYSTARTX02014;EVAR STUDIES: RENAL EVENTS DURING F-EVAR: A total of three main renal arteries and two accessory renal arteries became occluded during the procedure. These were all due to technical issues, except one accessory renal artery in which the artery was intentionally covered. One patient required open surgery following the procedure. RENAL EVENTS DURING THE FOLLOW-UP: A total of 12 renal arteries (12 patients) were found to be occluded during follow-up. In two patients, the same side accessory renal artery was also occluded. Four (1.5%) patients lost one kidney and five (2.3%) patients underwent dialysis, three (1.4%) of which became permanent. A total of 16 cases of renal artery stenosis (16 patients) occurred during follow-up. Eight of these were treated and eight were observed. Segmental renal infarcts were found in six patients but renal function was not impaired. MESENTERIC EVENTS DURING F-EVAR: Three mesenteric events occurred during the f-EVAR procedures resulting in two deaths. One patient developed bowel ischemia due to embolization of the superior mesenteric artery (SMA); this patient died 13 days after the procedure from multiorgan failure. One patient died eights days after the procedure from mesenteric ischemia and bowel perforation. The third SMA event occurred during surgery with subsequent occlusion in early follow-up. MESENTERIC EVENTS DURING FOLLOW-UP: During follow-up, five (1.8%) SMA occlusions/partial occlusions and one SMA stenosis were noted. Three of the five patients with SMA occlusion/partial occlusion remained asymptomatic and no further intervention was necessary. One patient underwent SMA bypass surgery and in two patients, the problem solved by SMA stenting. A summary of the outcomes reported in the f-EVAR and OSR studies is shown in Table ES-2. ES-2.Summary of Outcomes: Fenestrated Endovascular Graft Versus Open Surgical Repair for Treatment of Juxtarenal Aortic AneurysmOutcomef-EVAROSRPooled Estimate (Rate)30-day mortality1.83.1Late mortality12.823.7Permanent dialysis0-2.50-3.5Loss of kidney1.5No report of kidney loss Incidence of post-op renal insufficiency: 14.4%Mesentric ischemia3.32.9Aortic rupture00Post-op cardiac complications1.510.7Post-op pulmonary complications0.713.4Post-op GI complications0.75.9Aneurysm expansion1.40Secondary intervention (Non-endoleak)8.87.8EndoleakType I: 4Type 2: 16.8Type III: 1.8N/AEndoleak required treatmentType I: 2.9Type 2: 3.3Type III: 1.1Graft migration1.5N/AGraft separation0.7Duration (Mean)Operation time (min)240287Hospital stay (days)613 SUMMARY: Short- and medium-term results (up to 2 years) of f-EVAR for the repair of JRA showed that outcomes in f-EVAR series compare favourably with the figures for the OSR series; however, uncertainty remains regarding the long-term results. The following observations are based on low quality evidence. F-EVAR has lower 30-day mortality than OSR (1.8% vs. 3.1%) and a lower late-mortality over the period of time that patients have been followed (12.8% vs. 23.7%).There is a potential for the loss of target vessels during or after f-EVAR procedures. Loss of a target vessel may lead to loss of its respective end organ. The risk associated with this technique is mainly due to branch vessel ischemia or occlusion (primarily among the renal arteries and SMA). Ischemia or occlusion of these arteries can occur during surgery due to technical failure and/or embolization or it may occur during follow-up due to graft complications such as graft migration, component separation, or arterial thrombosis. The risk of kidney loss in this series of f-EVAR studies was 1.5% and the risk of mesenteric ischemia was 3.3%. In the OSR studies, the risk of developing renal insufficiency was 14.4% and the risk of mesenteric ischemia was 2.9%.F-EVAR has a lower rate of postoperative cardiac and pulmonary complications.Endoleak occurs in 22.5% of patients undergoing f-EVAR (all types) and about 8% of these require treatment. Most of the interventions performed to treat such endoleaks conducted using a minimally invasive approach.Due to the complexity of the technique, patients must be appropriately selected for f-EVAR, the procedure performed by highly experienced operators, and in centers with advanced, high-resolution imaging systems to minimize the risk of complications.Graft fenestrations have to be custom designed for each patient to fit and match the anatomy of their visceral arteries. Planning and sizing thus requires scrutiny of the target vessels with a high degree precision. This is important not only to prevent end organ ischemia and infarction, but to avoid prolonging procedures and subsequent adverse outcomes.Assuming the average cost range of FEVAR procedure is $24,395-$30,070 as per hospital data and assuming the maximum number of annual cases in Ontario is 116, the average estimated cost impact range to the province for FEVAR procedures is $2.83M-$3.49M annually.