Note from the National Guideline Clearinghouse (NGC): The National Institute for Health and Clinical Excellence (NICE) commissioned an independent academic centre to perform a systematic literature review on the technology considered in this appraisal and prepare an assessment report. The assessment report for this technology appraisal was prepared by the Peninsula Technology Assessment Group (see the "Companion Documents" field).
Search Strategy
A range of electronic databases were searched for published studies of effectiveness and cost-effectiveness or cost-benefit of dual chamber pacing, encompassing completed or ongoing research: Medline, Cochrane Library (Central, CDSR), Embase, ISI-Web of Knowledge, Web of Science Proceedings, BIOSIS, DARE, HTA, Biomed Central. In addition, the Web sites of the National Research Register, Current Controlled Trials and US Food and Drug Administration (FDA) were searched. The full search strategy is detailed in Appendix 11.2 of the systematic literature review companion document.
Bibliographies were searched for further relevant publications. Members of the Advisory Group were asked to identify additional published or unpublished studies. Submissions to the National Institute for Health and Clinical Excellence (NICE) by technology sponsors as part of the NICE appraisal process were checked for additional published and unpublished literature. The specialized registry of the Cochrane Heart Group was searched by a member of the Cochrane Heart Group.
Inclusion and Exclusion Criteria
Population
Adults and children recruited in secondary and tertiary centres with a primary diagnosis of acquired symptomatic bradycardia, secondary to sick sinus syndrome, atrioventricular (AV) block, or chronic bifascicular block, and individuals with symptomatic bradycardia were included. People at any stage of disease progression were considered, subject to their eligibility for permanent pacing.
Exclusion Criteria
Studies were excluded if they reported on the following populations:
- People with carotid sinus syndrome and malignant vasovagal syncope
- People with a primary diagnosis of congestive heart failure or cardiomyopathy
- People with a primary diagnosis of atrial fibrillation, or atrial fibrillation from other causes without concomitant sick sinus syndrome or atrioventricular block
- People with a primary diagnosis of isolated tachycardia or tachycardia from other causes without concomitant sick sinus syndrome or atrioventricular block
Intervention
Studies of dual chamber pacemakers compared to single chamber pacemakers (ventricular, atrial or both, separately reported) for the treatment of symptomatic bradycardia in eligible population groups.
Exclusion Criteria
Studies will be excluded if reporting on the following pacing types:
- Bi-ventricular
- Bi-atrial
- Triple chamber
- Any type of temporary or diagnostic pacing
Studies on dual chamber, therapeutic, permanent pacemakers with any of the above were excluded when results were not reported separately.
Outcomes
See the "Major Outcomes Considered" field.
Composite outcomes made up of the above were also included.
Type of Studies
Systematic reviews or randomised, controlled parallel or crossover trials were included in the assessment of effectiveness.
Exclusion Criteria
- Non-randomised studies of effectiveness, case series and case reports, n of 1 trials, case-control studies, and cohort studies
- Studies in which insufficient methodological detail were reported to allow critical appraisal
- Studies of less than 48 hours duration
- Studies on patients with clinical indications for pacing other than those considered in this Technology Assessment review (TAR)
- Pre-clinical studies, models, or electrophysiology experimentation on human or other biological material
- Studies in animal models
- Studies not published in English, and for which translation in English is not available
In the review of cost effectiveness studies, reviews of economic studies were included.
Individual studies were considered only if they were full economic evaluations (i.e., those which considered costs and outcomes).
Identification
Studies identified from the literature search were independently assessed by two researchers for inclusion, with disagreement resolved by discussion. Full papers were retrieved and screened independently by two researchers for inclusion, with disagreement resolved by discussion.
Data Extraction Strategy
A data extraction sheet was developed by one researcher and piloted on a small subsample of papers. Data were extracted by one researcher and checked by another. Data were extracted retaining actual numbers where provided, or other summary measures as detailed in the published study.
Quality Assessment Strategy
Methodological quality of randomized controlled trials (RCTs) was assessed using the criteria detailed in Table 6 of the systematic literature review companion document.
The framework established by the QUORUM statement was used for the critical appraisal of systematic reviews.
The quality of cost-effectiveness and cost-utility studies were assessed using the frameworks published by in Sculpher and colleagues and Drummond and colleagues.
Where subgroup analyses were reported, the group considered their methodological quality using the following framework:
- Sample size, with two possibilities, all participants were included in the subanalysis or some were excluded based on pre-selection criteria
- Whether the analysis was preplanned
- Whether the baseline equality of groups was maintained in the subgroup
- Whether blinding was maintained
- Whether the power calculation in the original trial included the subgroup analysis
- Whether the subgroup was analysed on an intention to treat basis
- Whether loss to follow up was reported and how this compared to loss to follow-up in the main study