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 Liverpool Reviews and Implementation Group (LRIG), University of Liverpool (see the "Companion Documents" field).
Clinical Effectiveness
Search Strategy
The search included a number of strategies. The electronic databases were searched for the period from 1966 to March 2003 (See Table 3A in the assessment report). The search had no language restrictions. Search terms for electronic databases included a combination of index terms (e.g. sleep initiation and maintenance disorders or insomnia) and free text words (e.g. insomnia or sleeplessness) combined with specific drug terms (e.g. zaleplon or Sonata, zolpidem or Stilnoct, zopiclone or Zimovane). Details of the search strategies used and the number of references retrieved for each search are provided in Table A1, Appendix 1 of the assessment report.
Reference lists of retrieved articles and pharmaceutical company submissions were searched to identify further studies. Recent issues (October 2002 to June 2003) of relevant journals that might not yet have been indexed in electronic databases were handsearched; the journals searched included: European Psychiatry, Human Psychopharmacology: Clinical and Experimental, International Clinical Psychopharmacology, Psycho-pharmacology, Sleep, Sleep Medicine, Sleep Medicine Reviews, The British Journal of Psychiatry, The Journal of Clinical Psychiatry. Internet resources (including industry supported websites) were examined for information on clinical trials.
An advisory panel was established to guide the review process. The role of the advisory panel was to comment on the review protocol, to answer specific questions as the review progressed and to comment on an early draft of the review including identifying missed or ongoing studies.
Inclusion and Exclusion Criteria
The identified citations were assessed for inclusion through two stages and disagreements were resolved by discussion at each stage. Two reviewers independently scanned all the titles and abstracts and identified the potentially relevant articles to be retrieved. Full text copies of the selected papers were obtained and each assessed independently by at least two reviewers for inclusion.
Details of inclusion and exclusion criteria are presented in Table 3A of the assessment report.
Extended Review on Dependence and Withdrawal Symptoms
Drug trials are usually too short to be able to assess the development of drug dependence. Therefore the research group conducted an extended search to identify studies of other designs which might help address the question of the relative potential of the comparison drugs to induce drug dependence and withdrawal.
Search Strategy, Inclusion and Exclusion Criteria
Search terms for this expanded search included a combination of index terms (e.g. withdrawal syndrome, drug tolerance, drug withdrawal) and free text words (e.g. withdrawal, dependency, tolerance, rebound) combined with specific drug names including zaleplon or Sonata, zolpidem or Stilnoct, zopiclone or Zimovane. Search strategies did not include filters that would limit results to specific publication types or study designs. Only English-language reports were identified because of time restrictions. Details of the search strategies used and the number of references retrieved for each search are provided in Table A2 in Appendix 1 of the assessment report.
Electronic databases searched and inclusion and exclusion criteria are detailed in Table 3A of the assessment report.
Methods for Reviewing Cost Effectiveness
Search Strategy
A comprehensive review of the literature was undertaken to identify all published articles that could provide evidence with regard to the cost-effectiveness of newer hypnotic drugs for the management of insomnia.
The search included a number of strategies. Search terms for electronic databases included a combination of index terms (e.g. sleep initiation and maintenance disorders or insomnia) and free text words (e.g. insomnia or sleeplessness) combined with specific drug terms (e.g. zaleplon or Sonata, zolpidem or Stilnoct, zopiclone or Zimovane). Clinical terms were combined with economic terms (e.g. cost or economic).
Reference lists of retrieved articles and pharmaceutical company submissions were also searched to identify further studies. Internet resources (including industry supported websites) were examined for information on clinical trials.
Electronic databases searched are presented in Table 3A of the assessment report. Search strategies and results of the searches undertaken are provided in Table A3, Appendix 1 of the assessment report.
Inclusion and Exclusion Criteria
The aim of the economic review was to identify economic evaluations informed by clinical data from randomised controlled trials. After scanning the abstracts, all papers that appeared to be of potential value to the study were obtained. Using explicit, predetermined criteria (see Table 3A of the assessment report), two reviewers independently identified studies for inclusion in the cost-effectiveness review process. Disagreements were resolved through discussion. The inclusion and exclusion criteria used in the review are presented below.