Head injury.

s looked to be of relevance. Experts provided three useful papers. These abstracts were then independently read by two reviewers to identify those papers that should be obtained and read in full. At this point the only criteria used was the likelihood that the paper might describe a rule or provide factors in the acute assessment of the patient that might predict postconcussional syndrome. After this assessment 23 papers were selected for review HEAD INJURY UPDATE FULL GUIDELINE: DRAFT FOR CONSULTATION (FEB 2007) 37 A brief description of the rule proposed was extracted. Only one paper actually proposed a rule. Participant description focused on GCS levels, age, and the main inclusion and exclusion criteria. The outcome measures used were extracted. The definitions of long-term disability or post-concussive were heterogeneous. Data on specificity and sensitivity were recorded where possible. As only one paper provided a rule, these figures could only be calculated for this one paper. The prevalence of important outcomes was also recorded. A previous systematic review was also available to the project team and this informed the review. 2.9 Systematic review of medical radiation risks This review aimed to provide simple estimates of the radiation risks associated with CT of the head. The search produced 654 abstracts in MEDLINE and 260 in EMBASE (after duplicates had been removed). A search using the Google search engine revealed useful documents from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the National Radiological Protection Board (NRPB). Personal communications with the National Radiological Protection Board also provided papers and data which contributed to the review. Following abstract review and including the papers supplied by experts, 80 full articles were obtained and were reviewed to determine relevance. This identified 16 documents considered of relevance and these contributed to the text of this guideline.review and including the papers supplied by experts, 80 full articles were obtained and were reviewed to determine relevance. This identified 16 documents considered of relevance and these contributed to the text of this guideline. 2.10 Guideline methodology The guideline was commissioned by NICE and developed in accordance with the guideline development process outlined in 'The guidelines manual' updated in April 2006. Development prior to this stage (e.g. development of the scope, early reviewing) was carried out using the methodology outlined in the previous version of the manual (March 2005). HEAD INJURY UPDATE FULL GUIDELINE: DRAFT FOR CONSULTATION (FEB 2007) 38 2.11 Developing the clinical questions Clinical questions were developed to guide the literature searching process and to facilitate the development of recommendations by the guideline development group. The clinical questions were initially drafted by the review team and were refined and validated by the guideline development group. The questions were based on the scope (Appendix A). 2.12 Clinical literature search The aim of the literature search was to identify relevant evidence within the published literature, in order to answer the clinical questions identified. Searches of clinical databases were performed using generic and specific filters, relevant medical subject heading terms and free-text terms. NonEnglish studies and abstracts were not included. Each database was searched up to 8 January 2007. Papers identified after this date were not routinely considered. Search strategies can be found in appendix 1. The following databases were included in the literature search to identify relevant journal articles: • Medline (Dialog Datastar) 1951-2006 • Embase (Dialog Datastar) 1974-2006 • PsycINFO 1806-2006 • Health Economic and Evaluations Database (HEED) • NHS Economic Evaluation Database (NHSEED) Bibliographies of identified reports and guidelines were also checked to identify relevant literature. The Internet was searched to identify guidelines and reports. The following web sites were used to help identify these: • Members of the Guidelines International Network's web sites (http://www.g-i-n.net) HEAD INJURY UPDATE FULL GUIDELINE: DRAFT FOR CONSULTATION (FEB 2007) 39 • National Institute for Health and Clinical Excellence (NICE) (www.nice.org.uk) • National electronic Library for Health (NeLH) (http://www.nelh.nhs.uk) • Scottish Intercollegiate Guideline Network (SIGN) (www.sign.ac.uk) • US National Guideline Clearing House (www.guidelines.gov) • CMA Infobase (http://mdm.ca/cpgsnew/cpgs/) • NIH Consensus Development Program (http://consensus.nih.gov) • New Zealand Guidelines Group (http://www.nzgg.org.nz) 2.13 Hierarchy of clinical evidence There are many different methods of ranking the evidence and there has been considerable debate about which system is best. We used the system, developed by the Scottish Intercollegiate Guidelines Network (SIGN), shown in Table 1. HEAD INJURY UPDATE FULL GUIDELINE: DRAFT FOR CONSULTATION (FEB 2007) 40 Table 1: Levels of evidence for intervention studies (reproduced with permission of the Scottish Intercollegiate Guidelines Network) Level of evidence Type of evidence 1++ High-quality meta-analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias 1+ Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias 1Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias 2++ High-quality systematic reviews of case–control or cohort studies High-quality case–control or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal 2+ Well-conducted case–control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal 2Case–control or cohort studies with a high risk of confounding bias, or chance and a significant risk that the relationship is not causal 3 Non-analytic studies (For example, case reports, case series)