1. Physical examination for diagnosing disc herniation in patients with back pain: systematic review of diagnostic accuracy studies Daniëlle van der Windt and many others…. Primary Care Musculoskeletal Research Centre, Keele University EMGO Instituut and Department of General Practice, VU University medical centre, Amsterdam

2. Content  Objectives of the review  Writing the protocol: decisions  Difficulties & lessons learnt o searching & selecting papers o quality assessment o data extraction o data synthesis  Preliminary results  Discussion

3. Cochrane reviews of diagnostic accuracy  April 2003: Cochrane Steering Group decides to include reviews of diagnostic accuracy studies  Cochrane Diagnostic Reviewers Handbook: 2006 - 2008  Pilot reviews (n = 11)  Specific software has been developed  Publication of first protocols (2007) and reviews 2008?

4. Pilot review (Cochrane Back Review Group) Physical examination for the diagnosis of lumbar radiculopathy due to disc herniation in patients with low-back pain  Herniated intervertebral disc: cause of LBP < 2% of patients  Accurate clinical diagnosis of lumbar radiculopathy is desirable to avoid unnecessary (surgical) intervention  Physical examination  decision making process o referral for diagnostic imaging? o suitable candidate for surgery?

5. Objectives  To assess the diagnostic performance of tests performed during physical examination in the identification of disc herniation in patients with low-back pain o single tests o combinations of tests  To assess the influence of sources of heterogeneity on diagnostic performance

6. Writing the protocol - decisions  Definition of target condition o disc herniation (bulging, prolapse, extrusion, …) o lumbar radiculopathy o other specific causes  Selection of the reference standard o imaging o surgical findings o recovery following surgery  Physical examination for … o identifying presence of disc herniation (yes/no) o identifying level of disc herniation

7. Searching & selecting papers  Definition of search strategy based on research question  Definition of selection criteria  Diagnostic studies are not easy to identify  Use of a methodology filter is not recommended (Doust et al. 2005; Leeflang et al. 2006)  This review: use of a sensitive filter in Medline & Embase

8. Search results  Results in April 2007 (+ update April 2008): o Medline: 1529 hits+ 132 o Embase: 793 hits+ 82 o Cinahl: 321 hits+ 88  Additional hits without use of methodology filter: o Medline: 336  4 papers (< 1969) potentially relevant o Embase: 126  1 paper potentially relevant

9. Quality assessment  QUADAS tool (Whiting 2004): o 11 core items o 3 additonal items, relevant to this review - treatment between index and reference test - definition of cut-off points (positivity criteria) - interobserver variation  Two assessors, 3 rd in case of disagreement

10. Assessing quality: difficulties  Disagreements: 29% of all scored items  Some items seemed irrelevant to our review: o Spectrum of patients representative of those who will receive the test in practice?  rephrased: “Sample is representative of target population”  Some items are strongly related: o Reference test assessed independent of index test? o Results of reference test interpreted without knowledge of index test results?

11. Quality assessment: results

12. Data extraction  Characteristics of participants: setting, age, gender, history of low back pain  Test characteristics (including cut-offs / positivity criteria)  Study design  Results: diagnostic 2x2 table

13. Extracting data: difficulties  Poor reporting of essential aspects of study design: o patient sampling o reference standard o sequence of testing o who performed which test?  Diagnostic 2x2 table not always presented, or impossible to reconstruct  Poor reporting of results: even incorrect computations of diagnostic accuracy

14. Results  18 studies  2 case-control studies  16 cohort studies, 5 with a retrospective design  Reference test: o surgical findings: 10 studies o diagnostic imaging (MRI, CT): 6 studies o case-control studies: surgery for cases, MRI/CT voor controls  More than 10 different types of tests

15. surgical findings (reference test) pos neg a b a + b SLR + (true positive) (false positive) c d c + d SLR - (fase negative) (true negative) a + c b + d N Sensitivity: a / a + c  probability of positive test result when diseased Specificity: d / b+d  probability of negative test results when healthy Data extraction

16. Results: example Scoliosis

17. Results: example MRI CC Impaired tendon reflexes

18. Straight leg raising test CC Reference test: surgery Pooled estimates (bivariate): - sensitivity: 0.92 (0.87 - 0.95) - specificity: 0.28 (0.18 - 0.40)

19. Straight leg raising test Reference test: MRI/CT CC Reference test: surgery

20. Crossed straight leg raising test CC Crossed straight leg raising test Pooled estimates (bivariate): - sensitivity: 0.23 (0.21 - 0.25) - specificity: 0.89 (0.86 - 0.91)

21. Exploring sources of heterogeneity  SLR: diagnostic performance may be poorer  cohort studies compared to case control studies  exclusion of patients with previous back surgery  Limited information on important study characteristics  Number of studies for most tests very small

22. Discussion  Most studies address individual tests only  combination of multiple tests (patient history & PE) more relevant, and possibly more accurate  diagnostic models / prediction rules  No optimal reference standard to determine if pain is caused by disc herniation  Very few studies in primary care populations  Diagnostic performance of most tests used during physical examination tests is poor

23. Questions  SLR: sensitive, but not very specific  suitable for ex cluding disc herniation? (few false negatives)  SnNout  Crossed SLR: specific, but not very sensitive  suitable for in cluding disc herniation? (few false positives)  SpPin  Q1: Can we always rely on the SpPin & SnNout rules?

24. Questions CC Reference test: surgery Q2: What is more informative? - pooled sensitivity & specificity - Summary ROC curves

25.  Ingrid Riphagen (search strategy)  Manu Simons & Bert Aertgeerts (selection)  Carlo Ammendolia & Arianne Verhagen (quality assessment)  Mark Laslett (data extraction)  Rick Deyo, Vicky Pennick, Lex Bouter, Riekie de Vet  Peer reviewers (protocol & review) Acknowledgments