What is Evidence-based imaging process?

Transcription

1 What is Evidence-based imaging process?

2 What is evidence-based imaging? The concept evidence-based medical imaging (e.g Smith 2007) is still complex and contradictory. Imaging informed and based on the combination of clinical expertise and the best available research-based evidence, patient preferences and resources available. (Hafslund et al. 2008) Also terms evidence-based radiography (e.g. Keenan et al. 2001, Ebrahim 2005) evidencebased practice (e.g. Pitt 2004, Pickersgill 2007), evidence-based clinical practice (e.g. Bonnetti et al. 2006) and evidence-based medical practice (e.g. Omorphos & Kontos 2003, Banerjee & Van Dam 2006)

3 According to Ahonen (2007) the concept of radiography in health sciences has been determined as expertise of radiographers in the use of radiation, which is dual, dynamic, social and situation-related in nature, and typically based on versatile synthesis and it has both similarities and differences between health sciences, physics and technology.

4 Evidence-based imaging results Better diagnostic testing Better competency cost-effectiveness Safety Client satisfaction Qualtity in radiation use dose optimisation

5 The process 1) Recognizing the need for information or improvement 2) Formulating the clinical question 3) Identifying the litterature 4) Evaluating the litterature 5) Summarising the data 6) Applying the evidence.

6 Formulating the clinical question Qustion components: The patient group or population The intervention or clinical situation Outcomes E.g. In pediatric patient for six to 15 years is CT or MRI better to exclude hemorrage in severe headache?

7 High level systematic reviews Traditional descriptive reviews Startpoint of the review Startpoint a clearly defined question or a a hypothesis to be tested. Startpoint general question about the topic without hypothesis. Litterature search The aim is to find all publications about the topic also unpublished ones. Aim is to minimize publication and other biases. Search not systematic. Selecting the studies for the review Accurate description of the selection process and criteria to minimize subjective selection bias. No clear decription about litterature search, process and intake/exclusion criteria of the studies. Assessment of studies Systematic evaluation of the design, methodology and biased of the studies. Often inadequate evaluation of methodology And quality of the studies. Combinig results Conclusions are based on the best studies. Conclusions are based on all the studies found, not just on the best evidence. Reference: Teikari M (2001) Tarua ja totta systemaattisista kirjallisuuskatsauksista. Impakti 3/2001. FinOHTA, Stakes

8 Making inclusion/exclusion criteria Before any search done Patients or population groups Interventions, clinical situations Outcomes Study designs : which are included, which excluded Makes search more invisible and it is much easier to make a summary.

9 Identifying the litterature Identifying relevant databasis Identifying relevant keywords Making inclusion/exclusion criteria Selection process: 1. References 2. Abstracts 3. Full texts Final evaluation on the basis of full texts

10 Some most common health care databases Open access: PubMed d/ With licence: Cochrane libraries Science Direct, Cinhal, Medline, Ovid

11 In true systematic reviews two independent reviewers are used to exclude bias. Calculating Kappa index between reviewers. In addition to electronic databasis search also: reference lists of relevant articles, volumes of relevant journals published just as hard copies, conress abstract books, doctoral thesis

12 Assessing bias A bias is a systematic error, or deviation from the truth, in results or inferences. Biases can operate in either direction: different biases can lead to underestimation or overestimation of the true intervention effect. It is important to assess risk of bias in all studies in a review irrespective of the anticipated variability in either the results or the validity of the included studies. For instance, the results may be consistent among studies but all the studies may be flawed. In this case, the review s conclusions should not be as strong as if a series of rigorous studies yielded consistent results. (Higgins et al. 2008)

13 Level of evidence Best: Systamtic reviews, Randomised Controlled Clinical Trials 2nd best: Cohort study 3rd best:case-control studies 4rd best: Cross-sectional 5th best: Case-series, Case reports Lowest level evidence: Expert opinion without explicit critical appraisal, or based on physiology, bench research or first principles.

14 Making the summary Qualitative summary or metaanalysis. Qualitative summary: tabulation for great help. Tabulate: population or patient group, intervention, outcome, design, methods and level of evidence.

15 Meta-analysis Combines results of studies statistically Is based on the results of individual studies (not individual subjects inside the studies) The studies must be similar in relation to res. questions, patient groups/populations, interventions, outcomes and designs otherwise not comparable One way to evaluate sensitivity and specificity of studies

16 Applying the evidence The type of evidence/outcome that is applicable depends on the type of information need. The form of summary must be suitable to ansver the question. On the basis of clinical decision making, QA and patient care

17 References Ahonen, S.-M. (2007) Radiography - a conceptual approach. Radiography. In Press, Corrected Proof, Available online 31 August 2007 doi: /j.radi Banerjee, S. & Van Dam, J. (2006) CT colonography for colon cancer screening. Gastrointestinal Endoscopy. 63(1), Bonetti, D. Pitts, N.B. Eccles, M. Grimshaw, J. Johnston, M. Steen, N. Glidewell, L. Thomas, R. Maclennan, G. Clarkson, J.E. & Walker A. (2006) Applying psychological theory to evidence-based clinical practice: identifying factors predictive of taking intra-oral radiographs. Social Science & Medicine 63(7), Ebrahim, N. (2005) Radiographers knowledge about concepts and approaches to evidence-based practise. The South African Radiographer 43(2), Hafslund, B. Clare, J. Graverholt, B. Wammen Nortwelt, M. (2008) Evidence-based radiography. Radiography 14; Higgins, JPT. Green, S. (editors). Cochrane Handbook for Systematic Reviews of Interventions Version [updated September 2008]. The Cochrane Collaboration, Available from

18 References Keenan, L.Y. Muir, C. & Cuthbertson, L.M. (2001) Maximizing the benefit--minimizing the risk: the developing role of radiographers in performing intravenous injections. British Journal of Radiology 74(884), Medina LS, & Blackmore CC (2006) Evidence-based imaging. Optimising patient care in imaging. Springer Omorphos, S. & Kontos, A. (2003) Cervical spine imaging in children under 9 after trauma. Emergency Medicine Journal 20(2), Pickersgill, R. (2007) Evidence-based practice: an introduction through skills mix. Synergy, Pitt, E. (2004) Role of flexion/extension radiography in neck injuries in adults. Emergency Medicine Journal 21(5), Smith, T. (2007) Evidence based medical imaging (EBMI) Radiography [In Press, Corrected Proof, 2007]