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Pre-Employment Exams A Spinal Focus

Pre-Employment Exams A Spinal Focus. Spinal Intrinsic Risk Factors Dr David McGrath 2008 www.drdavidmcgrath.com.au. Questions. What are They ? How Bad are they ? Can we find them ? Should we find them ?. Possible Risk Factors. Current Pain Old Injuries

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Pre-Employment Exams A Spinal Focus

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  1. Pre-Employment ExamsA Spinal Focus Spinal Intrinsic Risk Factors Dr David McGrath 2008 www.drdavidmcgrath.com.au

  2. Questions • What are They ? • How Bad are they ? • Can we find them ? • Should we find them ?

  3. Possible Risk Factors • Current Pain • Old Injuries • Congenital or Acquired Deformities • Anthropometric Extremes • Age • Gender • Level of Fitness • Strength and Robustness • Imaged Pathology

  4. Assessing the Risk(hypothetical non specific risk factor OR=17 )

  5. Deductions • With a prevalence of 10%, and an absolute risk contribution of ½,we need approximately 100 examinations to reduce, the adverse employment outcomes by 50% (by not employing or effective risk management )

  6. Detection(sensitivity 80%, specificity 77% )

  7. The Risk Adjusted Company(Perfect Intervention=All those identified with risk factor prevented from bad outcome NNT=2)First number indicates employees with risk factorSecond number indicates, employees without risk factor

  8. Risk Intervention Effectiveness (Compared to natural company history with 50% bad outcome)NNT=1/(6/8-4/8)=4

  9. Company after Realistic Intervention (NNT=4)

  10. Non-Hiring Option(28 at-risk diagnosed and not hired, leading to 72 remaining )(8 with risk factor excluded, 20 non risk employees excluded )(72 remaining employees, 2 have risk factor,70 don’t )50% of the 2=1 and 5(1/2) % of 70=4 have bad outcome

  11. After Hiring another 28 in 139 exams total (excluding 39 candidates, only 11 of which have the risk factor, while 28 don’t )

  12. Comparing Outcomes

  13. Remember • Odds Ratio=17 (ie relatively high) • Detection se=80% sp=77% (ie good) • NNT=4 Risk Intervention (ie good) • Interventions for 28% (20% no risk) • Exams=139% with rejection strategy • Rejected applicants without risk=28 (20% of candidates) • Rejected applicants with risk=11 (8% candidates, but 10% prevalence)

  14. Summary • With Detection/Risk Intervention strategy, we examine 100% employees,20% less bad outcome, and intervene on 28% employees (20% of which don’t have risk) • With Detection/Don’t hire policy, we have, 25 % less bad outcome, and examine, 139 % prospective employees, reject 20% with no risk

  15. Things To Consider • Cost of Exams • Stigma to rejected applicants • Cost of interventions • Cost and Significance of Bad Outcomes

  16. Armed Forces • Cost of Training High • Cost of Intervention High • Cost of Bad Outcome High • Cost of Exams relatively Cheap • Stigma of Rejection ??

  17. Trial Of Fire • Relax initial entry criteria • Boot Camp survival test (many compo claims arise from this period) • Chance of re-entry if fitness or strength is limiting factor • Not generally available to high end, service skill occupations e.g. pilots, aircrew

  18. Spines • What’s Worth Looking For ? • What’s the best detection method ? • What’s the cost/benefit ? For either the non hire or risk intervene option • What are technical, legal, ethical, social limitations

  19. Recurrent Back Pain • LBP >30 days during past year, increased risk OR=4.8 long lasting BP OR=3.3 Leg pain OR=5.9 Medical Discharge (Hestbaek 2005) n=1711 Danish Military Recruits Conscription • Generally this factor is thought to have good Se, but poor Sp. Also poor Reliability.

  20. Muscle Strength • Strength testing alone has no predictive value for work place injuries (Harbin G 2005) n=2,482 Food factory study • Likely discrimination against women, certain ethnic groups, and handicapped, using the Detect/Don’t hire policy

  21. Job Matching • With employees who had matching physical capacity, to inherent requirements of job, incidence of injuries was 3% • With employees, without matching capacity, incidence of injuries was 33% NNT=3 in this instance (Harbin G 2005) Factory Workers • 38% physical theoretical mismatch in an industry with a high incidence of LBP (Pedersen DM 2005) Utah Mechanics

  22. Scoliosis etc • Kyphosis/lordosis (side plane) • Skewed pelvis • Scoliosis (frontal plane) • Rotoscoliosis (front, axial) • Sparse reliable, valid data, on occupation outcome measures • OR=3.0 LBP adolescents (Kovac’s 2005)

  23. Congenital Malformations • Dysraphism (usually detected at birth) • Dysegmentalism (sacralisation, lumbarisation,accessory articulations ) • No valid data

  24. Disc Disease • Isolated Disc Resorption (significant loss of disc height) • Bulges • Prolapses • V.E.P Osteophytic Outgrowth • Sparse, unreliable data

  25. Scheuermann’s Disease • The definition, has relaxed from the original thoracic kyphosis deformity (to a number of vertebral end plate deformities) • No reliable /valid data on risk for various occupations

  26. Isthmic Spondylolitheses • No reliable /valid data on occupational risk • Overall risk perceived to be low

  27. Intervertebral Canal Pathology • Congenital or Acquired Spinal Stenosis • Spinal Cord Pathology • Other Spinal canal Pathology • No Reliable or Valid data for occupations

  28. Muscular Imbalance • Signs of muscular Irritability • Associated geometry deformity • Associated poor dynamic range of specific joints • Low reliability (inter or intra observer ) • No valid data • Assume similar to scoliosis ? (OR=3 LBP)

  29. Body Mass Index • Mild positive association, increasing for longer pain duration • Positive association, unlikely to be causal, as correlation disappears with monozygotic twins (Leboeuf Yde 1999 ) n=29,424 twins “Probable, weight increase with chronicity”

  30. Co-Morbidity • Positive association of LBP and headache and asthma (Hestbaek L 2006 ) n=9,567 Age cohort 12-22 The presence of two other disorders increased the probability of LBP considerably Frail subgroup drops from 60% to 25 % at age 22. “a common origin should be considered”

  31. Smoking • Association between smoking and LBP (Leboeuf-Yde 1999 ) The association is not likely to be causal, as there is no dose response relationship, and disappears with twin study

  32. LBP Adolescents • Strong correlation between adolescent LBP and adult LBP OR=4 • 8 year follow up study • N=10,000 • Dose Response Relationship (Hestbaek L 1999 Danish Study) “Future Research, should focus on young Population “

  33. LBP Schoolchildren • LBP not related to heredity • Scoliosis related to heredity • Strong association between pain in bed or upon arising and LBP. OR=13 • LBP and Scoliosis OR=3 • LBP and Leg length difference OR=1.3 • LBP and sport practice more than 2/week OR=1.2 (Kovacs FM 2005 Spanish cross sectional study n=16,394)

  34. LBP and Schoolchildren(continued) • No Association for LBP and alcohol intake, cigarette smoking, BMI, book transport method, hours of leisure sitting. • Point prevalence (7 day period) was 17% boys and 33% girls.

  35. Spondylosis • Not valuable as a diagnoses • The population attributable risk is around 15%, as an association with LBP, and thus can be viewed as an intrinsic risk factor.

  36. Gender • Women more at risk of developing chronic LBP OR=2.65 Military Physical training OR=2.49 Military Occupation OR=2.91 Off Duty Activities OR=0.05 Sporting Activity OR=3.17 Overall (Strowbridge NR 2005) n=928 new cases English Military Prospective Study

  37. Intelligence and Education • In one study, LBP in military recruits, intelligence protects OR=5, while having parents with high education was slightly negative OR=1.9 (Hestbaek L 2005)

  38. Multiple Minor Risk Factors • A little bit of this, a little bit of that • Do risk factors, add or compound ? A slightly bad neck and a crook back • No valid studies

  39. What to Do ? • History (detailed or cursory ) • History + Exam (detailed or cursory ) • History + Exam + XR (whole spine or Lx) • History +Exam+ XR + Further Imaging • History + Exam + Functional Matching (quantitative or qualitative job/physical characteristics ) • None of the Above

  40. Strategies for Less than Ideal Math's • Identify Risk Factors as an awareness promoting exercise and Institute an early reporting system • Consider, job matching trial (recall Harbin NNT=3) and/or • Aggressive early intervention (secondary prevention) • Avoiding, costly intervention on false positives, non effective intervention on true positives, or the stigma of non-hire (true or false positive) • Employment exams as an Insurance policy, against fraudulent or excessive claims ?

  41. Things To Re-Consider • Cost of Exams • Stigma to rejected applicants • Cost of interventions (primary or secondary) • Cost and Significance of Bad Outcomes • Potential Role of Exams as Part of Employee Care Program

  42. Questions & Lively Discussion • Are other areas of the body better off ? • How reliable/valid are cardiovascular risk factors ? • How to better integrate intrinsic and extrinsic risk factors ? • Most diseases are multi-risk generated ?

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