Ontario health technology assessment series
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Ont Health Technol Assess Ser · Jan 2005
Biventricular pacing (cardiac resynchronization therapy): an evidence-based analysis.
In 2002, (before the establishment of the Ontario Health Technology Advisory Committee), the Medical Advisory Secretariat conducted a health technology policy assessment on biventricular (BiV) pacing, also called cardiac resynchronization therapy (CRT). The goal of treatment with BiV pacing is to improve cardiac output for people in heart failure (HF) with conduction defect on ECG (wide QRS interval) by synchronizing ventricular contraction. The Medical Advisory Secretariat concluded that there was evidence of short (6 months) and longer-term (12 months) effectiveness in terms of cardiac function and quality of life (QoL). More recently, a hospital submitted an application to the Ontario Health Technology Advisory Committee to review CRT, and the Medical Advisory Secretariat subsequently updated its health technology assessment. ⋯ Owing to the limitations of drug therapy, cardiac transplantation and device therapies have been used to try to improve QoL and survival of patients with chronic HF. Ventricular pacing is an emerging treatment option for patients with severe HF that does not respond well to medical therapy. Traditionally, indications for pacing include bradyarrhythmia, sick sinus syndrome, atrioventricular block, and other indications, including combined sick sinus syndrome with atrioventricular block and neurocardiogenic syncope. Recently, BiV pacing as a new, adjuvant therapy for patients with chronic HF and mechanical dyssynchrony has been investigated. Ventricular dysfunction is a sign of HF; and, if associated with severe intraventricular conduction delay, it can cause dyssynchronous ventricular contractions resulting in decreased ventricular filling. The therapeutic intent is to activate both ventricles simultaneously, thereby improving the mechanical efficiency of the ventricles. About 30% of patients with chronic HF have intraventricular conduction defects. (6) These conduction abnormalities progress over time and lead to discoordinated contraction of an already hemodynamically compromised ventricle. Intraventricular conduction delay has been associated with clinical instability and an increased risk of death in patients with HF. (7) Hence, BiV pacing, which involves pacing left and right ventricles simultaneously, may provide a more coordinated pattern of ventricular contraction and thereby potentially reduce QRS duration, and intraventricular and interventricular asynchrony. People with advanced chronic HF, a wide QRS complex (i.e., the portion of the electrocardiogram comprising the Q, R, and S waves, together representing ventricular depolarization), low left ventricular ejection fraction and contraction dyssynchrony in a viable myocardium and normal sinus rhythm, are the target patients group for BiV pacing. One-half of all deaths in HF patients are sudden, and the mode of death is arrhythmic in most cases. Internal cardioverter defibrillators (ICDs) combined with BiV pacemakers are therefore being increasingly considered for patients with HF who are at high risk of sudden death. CURRENT IMPLANTATION TECHNIQUE FOR CARDIAC RESYNCHRONIZATION: Conventional dual-chamber pacemakers have only 2 leads: 1 placed in the right atrium and the other in the right ventricle. The technique used for BiV pacemaker implantation also uses right atrial and ventricular pacing leads, in addition to a left ventricle lead advanced through the coronary sinus into a vein that runs along the ventricular free wall. This permits simultaneous pacing of both ventricles to allow resynchronization of the left ventricle septum and free wall. MODE OF OPERATION: Permanent pacing systems consist of an implantable pulse generator that contains a battery and electronic circuitry, together with 1 (single-chamber pacemaker) or 2 (dual-chamber pacemaker) leads. Leads conduct intrinsic atrial or ventricular signals to the sensing circuitry and deliver the pulse generator charge to the myocardium (muscle of the heart). COMPLICATIONS OF BIVENTRICULAR PACEMAKER IMPLANTATION: The complications that may arise when a BiV pacemaker is implanted are similar to those that occur with standard pacemaker implantation, including pneumothorax, perforation of the great vessels or the myocardium, air embolus, infection, bleeding, and arrhythmias. Moreover, left ventricular pacing through the coronary sinus can be associated with rupture of the sinus as another complication. CONCLUSION OF 2003 REVIEW OF BIVENTRICULAR PACEMAKERS BY THE MEDICAL ADVISORY SECRETARIAT: The randomized controlled trials (RCTs) the Medical Advisory Secretariat retrieved analyzed chronic HF patients that were assessed for up to 6 months. Other studies have been prospective, but nonrandomized, not double-blinded, uncontrolled and/or have had a limited or uncalculated sample size. Short-term studies have focused on acute hemodynamic analyses. The authors of the RCTs reported improved cardiac function and QoL up to 6 months after BiV pacemaker implantation; therefore, there is level 1 evidence that patients in ventricular dyssynchrony who remain symptomatic after medication might benefit from this technology. Based on evidence made available to the Medical Advisory Secretariat by a manufacturer, (8) it appears that these 6-month improvements are maintained at 12-month follow-up. To date, however, there is insufficient evidence to support the routine use of combined ICD/BiV devices in patients with chronic HF with prolonged QRS intervals. SUMMARY OF UPDATED FINDINGS SINCE THE 2003 REVIEW: Since the Medical Advisory Secretariat's review in 2003 of biventricular pacemakers, 2 large RCTs have been published: COMPANION (9) and CARE-HF. (10) The characteristics of each trial are shown in Table 1. The COMPANION trial had a number of major methodological limitations compared with the CARE-HF trial. Table 1:Characteristics of the COMPANION and CARE-HF Trials*COMPANION, 2004CARE-HF, 2005Optimal Therapy vs. BiV Pacing vs. BiV Pacing/ICD†Optimal Therapy vs. BiV PacingPopulationNew York Heart Association class III/IV heart failureEF† ≤ 0.35QRS† ≥ 120 msN1,520(optimal therapy, n = 308; BiV pacing, n = 617; BiV pacing/ICD, n = 595)813Follow-up (months)Median, 16Mean, 29Comment- Definition of "hospitalization" in primary outcome changed 3 times during trial w/o documentation in protocol and FDA† not notified (dominant outcome for composite endpoint).- Dropouts/withdrawals/crossovers not clearly described.- Study terminated early.- No direct comparison between BiV pacing vs. BiV pacing/ICD.- High number of patients withdrew from optimal therapy to device arms.- Not blinded.Not blinded*COMPANION; (9) CARE-HF. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2005
Deep brain stimulation for Parkinson's disease and other movement disorders: an evidence-based analysis.
To determine the effectiveness and adverse effects of deep brain stimulation (DBS) in the treatment of symptoms of idiopathic Parkinson's disease, essential tremor, and primary dystonia and to do an economic analysis if evidence for effectiveness is established. ⋯ According to the estimates of prevalence and evidence of effectiveness, there is a shortfall in the numbers of DBS currently done in Ontario for drug-resistant PD, essential tremor, and primary dystonia.Since complication rates are lower if DBS is performed in specialized centres, the number of sites should be limited.The cost per procedure to institutions with the expertise to undertake DBS and the human resource considerations are likely to be limiting factors in the further diffusion of DBS.
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Ont Health Technol Assess Ser · Jan 2005
Sacral nerve stimulation for urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence: an evidence-based analysis.
The aim of this review was to assess the effectiveness, safety, and cost of sacral nerve stimulation (SNS) to treat urinary urge incontinence, urgency-frequency, urinary retention, and fecal incontinence. ⋯ In summary, there is level 2 evidence to support the effectiveness of SNS to treat people with urge incontinence, urgency-frequency, or urinary retention. There is level 4 evidence to support the effectiveness of SNS to treat people with fecal incontinence. To qualify for SNS, people must meet the following criteria: Be refractory to behaviour and/or drug therapyHave had a successful test stimulation before implantation; successful test stimulation is defined by a 50% or greater improvement in voiding function based on the results of a voiding diary. Test stimulation periods range from 3 to 7 days for patients with urinary dysfunctions, and from 2 to 3 weeks for patients with fecal incontinence.Be able to record voiding diary data, so that clinical results of the implantation can be evaluated.Patients with stress incontinence, urinary retention due to obstruction and neurogenic conditions (such as diabetes with peripheral nerve involvement) are ineligible for sacral nerve stimulation. Physicians will need to learn how to use the InterStim System for Urinary Control. Requirements for training include these: Physicians must be experienced in the diagnosis and treatment of lower urinary tract disorders and should be trained in the implantation and use of the InterStim System for Urinary Control. (ABSTRACT TRUNCATED)
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This health technology policy assessment will answer the following questions: When should in-room air cleaners be used?How effective are in-room air cleaners?Are in-room air cleaners that use combined HEPA and UVGI air cleaning technology more effective than those that use HEPA filtration alone?What is the Plasmacluster ion air purifier in the pandemic influenza preparation plan?The experience of severe acute respiratory syndrome (SARS) locally, nationally, and internationally underscored the importance of administrative, environmental, and personal protective infection control measures in health care facilities. In the aftermath of the SARS crisis, there was a need for a clearer understanding of Ontario's capacity to manage suspected or confirmed cases of airborne infectious diseases. In so doing, the Walker Commission thought that more attention should be paid to the potential use of new technologies such as in-room air cleaning units. It recommended that the Medical Advisory Secretariat of the Ontario Ministry of Health and Long-Term Care evaluate the appropriate use and effectiveness of such new technologies. Accordingly, the Ontario Health Technology Advisory Committee asked the Medical Advisory Secretariat to review the literature on the effectiveness and utility of in-room air cleaners that use high-efficiency particle air (HEPA) filters and ultraviolet germicidal irradiation (UVGI) air cleaning technology. Additionally, the Ontario Health Technology Advisory Committee prioritized a request from the ministry's Emergency Management Unit to investigate the possible role of the Plasmacluster ion air purifier manufactured by Sharp Electronics Corporation, in the pandemic influenza preparation plan. ⋯ There were no existing health technology assessments on air cleaning technology located during the literature review. The literature search yielded 59 citations of which none were retained. (ABSTRACT TRUNCATED)
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Ont Health Technol Assess Ser · Jan 2005
Implantable cardioverter defibrillators. Prophylactic use: an evidence-based analysis.
The use of implantable cardiac defibrillators (ICDs) to prevent sudden cardiac death (SCD) in patients resuscitated from cardiac arrest or documented dangerous ventricular arrhythmias (secondary prevention of SCD) is an insured service. In 2003 (before the establishment of the Ontario Health Technology Advisory Committee), the Medical Advisory Secretariat conducted a health technology policy assessment on the prophylactic use (primary prevention of SCD) of ICDs for patients at high risk of SCD. The Medical Advisory Secretariat concluded that ICDs are effective for the primary prevention of SCD. Moreover, it found that a more clearly defined target population at risk for SCD that would be likely to benefit from ICDs is needed, given that the number needed to treat (NNT) from recent studies is 13 to 18, and given that the per-unit cost of ICDs is $32,000, which means that the projected cost to Ontario is $770 million (Cdn). Accordingly, as part of an annual review and publication of more recent articles, the Medical Advisory Secretariat updated its health technology policy assessment of ICDs. ⋯ Using the GRADE Working Group criteria, the quality of these 3 trials was examined (Table 2). Quality refers to the criteria such as the adequacy of allocation concealment, blinding and follow-up. Consistency refers to the similarity of estimates of effect across studies. If there is important unexplained inconsistency in the results, our confidence in the estimate of effect for that outcome decreases. Differences in the direction of effect, the size of the differences in effect, and the significance of the differences guide the decision about whether important inconsistency exists. Directness refers to the extent to which the people interventions and outcome measures are similar to those of interest. For example, there may be uncertainty about the directness of the evidence if the people of interest are older, sicker or have more comorbidity than those in the studies. As stated by the GRADE Working Group, the following definitions were used to grade the quality of the evidence: HIGH: Further research is very unlikely to change our confidence n the estimate of effect.MODERATE: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.LOW: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.VERY LOW: Any estimate of effect is very uncertain.Table 2:Quality of Evidence - MADIT I, MADIT II, and SCD-HeFT*TrialDesignQualityConsistencyDirectness†Quality GradeMADIT IRCTImbalance in β-blocker usage between study arms.The overall number of patients from which the study was drawn was not reported.Selection bias may have occurred since patients were selected for randomization if they did not respond to procainamide, thereby introducing a potential bias into the medication arm.Specific details regarding allocation concealment and blinding procedures were not provided.Single-chamber ICD used in study.Trial started with transthoracic implants, and then switched to nontransthoracic implants.Ischemic cardiomyopathy only.5-year NNT = 2.The overall number of Moderate patients from which the study was drawn was not reported.Selection bias may have occurred since patients were selected for randomization if they did not respond to procainamide, thereby introducing a potential bias into the medication arm.ModerateMADIT IIRCT~ 90% of patients were recruited ≥6 months post-MI; 20% of control group died after mean 20-month follow-up.How and where patients recruited?Specific details regarding allocation concealment/blinding procedures not provided.Subset had MADIT I criteria; post hoc analysis of incomplete data suggested "weak-moderate evidence that ICD effect greater in inducible than noninducible patients in MADIT II." (5;6)First study to assess both single- and dual-chamber ICD devices for primary prevention.Programming of device and medications left to the discretion of the patients' physician.Higher rate of hospitalization for new or worsened heart failure in the group receiving the ICDs compared to conventional therapy (19.9% versus 14.9% respectively).Ischemic cardiomyopathy only.5-year NNT = 6.How and where patients Weak recruited?Subset had MADIT I criteria.WeakSCD-HeFTRCTStatistically significant difference in β-blocker usage between treatment groups at last follow-up.Drug arms double-blinded.Shock-only single-lead device. Antitachycardia pacing not permitted.Ischemic and nonischemic cardiomyopathy.There was a statistically significant difference in terms of the NYHA prespecified subgroups analysis. The NYHA subgroups were prespecified a priori and the results of the interaction tests were significant. Yet, ICD treatment had a significant benefit in patients in NYHA class II but not in those in NYHA class III. (ABSTRACT TRUNCATED)