Transcript
  • 1

    Occupational exposures and rotator cuff disease / biceps tendinitis

    Aberdeen Pain Research CollaborationEpidemiology Group, Department of Public Health

    Dr Gareth JonesSenior Lecturer in Epidemiology

    One-Month Prevalence

    Shoulder: 24%

    Low back: 28%

    Headache: 15%

    Abdomen: 8%

    Foot: 13%

    Low back: 28%

    Thigh / Hip: 28%

    Hand: 15%

    Knee: 21%

    Abdomen: 8%

    Shoulder Pain Aetiological Studies

    • Miranda et al 2001– Physical strenuousness – Working with flexed trunk– Working in twisted posture – Working with rotated neck – Working with elevated arms

    • Palmer et al 2001a– Keyboard use

    • Bergenudd et al 1988– Workplace dissatisfaction

    • Palmer et al 2001b– Use of vibrating tools

  • 2

    Limitations of Aetiological Studies

    • Cross-sectional / Case-control studies– Onset of shoulder pain– Temporal course of events

    • Studies limited to one workforce– External validity – Particular combinations of exposures

    • Healthy worker effect– Solution: Longitudinal studies– Limitation: Very resource intensive

    Harkness et al 2003

    • Prospective cohort

    • 12 occupational groups

    • 803 subjects free of shoulder pain

    • Follow-up– 12 months – 24 months – New prevalence: 15% – New prevalence: 15%

    Harkness et al 2003

    10.0

    Pai

    n O

    nset

    10.0

    Pai

    n O

    nset

    0.1

    1.0

    OR

    (95%

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    of S

    houl

    der P

    YesNo

    Lift heavyweights

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der P

    Push / pullweights

    Lift aboveshoulder

    Work withelevated arms

    Carry weighton shoulder

    YesNo

    Lift heavyweights

    Fredriksson et al 1999

    • Prospective study

    • Range of occupations

    • 485 subjects

    • Predictors of shoulder pain onset– High mental load at work– Monotonous work– Low social support

  • 3

    Prognosis of Shoulder Pain

    • Few studies in general population

    • Patients in primary care– More severe symptoms than general populationy p g p p– Croft et al 1996

    • 49% reported a complete recovery at 18 months

    – van der Windt et al 1996• 59% fully recovered at 12 months

    Rotator Cuff / Biceps Tendon

    Shoulder Pain

    • Pain can originate from many sites– Tendinitis– Bursitis– Referred painp

    • Cervical or thoracic spine• Internal organs

    • Lack of evidence as to what clinical conditions (with pain as a symptom) have distinct aetiological aspects

    Rotator Cuff / Biceps Tendon

    • Four muscles and their tendons– Subscapularis– Supraspinatus– Infraspinatusp– Teres minor

    • Tendons form continuous cuff around humeral head

    • Pathology– Inflammation– Damage (tear)

  • 4

    Case Ascertainment

    • Presenting symptoms– Pain (antero-laterally)– Inhibition of movement

    • Gold standard– Imaging

    • Physical findings– Tenderness on palpation– Clinical examination

    • Jobe• Gerber• Neer• Hawkins

    • Clinical practice– Patient history– Clinical examination

    Descriptive Epidemiology

    • General population– Seldom recorded– Estimates

    • ~10% of cases of persistent shoulder pain• ~85% of patients presenting to primary care with shoulder pain have a85% of patients presenting to primary care with shoulder pain have a

    rotator cuff tear

    • Working population– Rotator cuff syndrome: 6.8% (men) and 9.0% (women)– Rotator cuff tendinitis: 2.0%– Rotator cuff tendinitis: 3.8%– Biceps tendinitis: 0.5%

    Descriptive Epidemiology

    • Inconsistent evidence of gender differences

    • Clear increase in prevalence with age– Longer cumulative exposure to risk factorsg p– Age-related degenerative changes in rotator cuff tendons– Disease of long duration

    Occupation

    • Supraspinatus tendinitis– House painters 4.4%– Fish processing workers 5.0%– Slaughterhouse workers 6.9%

    W ld 27%– Welders 27%

    • Infraspinatus tendinitis– Fish processing workers 12%

    • Supraspinatus tendon pathology (MRI)– Machinists / Mechanics / Painters 38%

    Occupationalaetiology?

  • 5

    Occupation

    • Only a marker for aetiological factor

    • Provides no task-specific information

    • Need to study specific work exposures

    Aims and Objectives

    Aims and Objectives

    • To summarise the existing epidemiological evidence with respect to the associations between occupational-related exposures and rotator cuff disease and / or biceps tendinitis

    • Specific objectives– To present exposure-response patterns, where present– To assess any impact of gender– To evaluate the evidence with respect to prognosis

    Outcome Definition

    • Rotator cuff disease and / or biceps tendinitis

    • Standard definitions– No diagnostic guidelines for physical diseases in ICD-10g g p y– No consensus reached re: diagnostic criteria for shoulder

    disorders

    • Outcome:– Exception:

    Pain plus objective physical findingsShoulder pain plus tenderness on palpation alone

  • 6

    Methods

    Methods: Literature Search

    • Electronic bibliographic databases– Medine (from 1966)– Embase (from 1980)

    • Search date– February 7th, 2007

    • Three searches– Outcomes of interest– Epidemiological search terms– Exposures of interest

    Methods: Literature Search

    ‘Shoulder’search

    shoulderrotator cuff

    i t

    ‘Epidemiology’search

    epidemiolo$aetiolo$

    ti l $

    ‘Occupational’search

    occupation$employment$j b$ “OR”supraspinatus

    infraspinatusteres minorsubscapularisbiceps tend$glenohumeralimpingement

    “OR”

    etiolo$risk factor$predictive factor$risk marker$odds ratio$hazard ratio$risk ratio$rate ratio$prevalence ratio$relative risk$

    “OR”

    job$work$task

    “OR”

    Methods: Literature Search

    ‘Shoulder’search

    ‘Epidemiology’search

    ‘Occupational’search

    Combination(‘AND’)

    Titlesfor review

    Removeduplicates

    Limit to EnglishLimit to Human

  • 7

    Methods: Review Strategy

    Reviewer 2Reviewer 1

    Titlesfor review

    Reviewer 3

    ReviewabstractsDiscard

    Agree to reject Agree to acceptDisagree

    Methods: Assessing Study Quality

    • Combination– Objective characteristics– Subjective assessment

    T i• Two reviewers

    • Ten areas of methodology– Study design – Confounding– Sample size – Blinding– Sampling method – Objective exposure– Participation / follow-up – Exposure-response data– Bias – Outcome measurement

    Methods: Contributory Evidence

    • Very stringent outcome criteria– Anticipated few studies

    • Many studies with self-reported shoulder painy p p

    • Contributory evidence– Studies identified from literature search– Subjectively measured outcome– High quality prospective cohort studies

    Methods: Grading of Evidence

    Evidence of causal relationshipGrade

    Strong evidence (causal relationship is very likely)+++

    Moderate evidence (causal relationship is likely)++

    Weak evidence (causal relationship is possible)+

    Insufficient evidence of a causal association0

    Evidence suggesting lack of causal association–

  • 8

    Main Findings

    Results: Literature Search

    ‘Outcome’n = 56,174

    ‘Epidemiology’n = 1,456,900

    ‘Occupational’n = 1,305,486

    Boolean ‘AND’n = 1062

    Titles for reviewn = 651

    Duplicatesn = 301

    English / Humann = 110

    Inclusion / Exclusion Criteria

    • Review of titles– Suggestion that outcome included pain / disability in the

    shoulder / neck / upper limb

    • Review of abstracts– Explicit mention that outcome was assessed by self-report– Explicit mention that only non-occupational exposures were

    assessed

    Inclusion / Exclusion Criteria

    • Review of full papers – Outcome– Study used solely a self-reported outcome– Outcome was pain plus tenderness alone

    • Review of full papers – Exposure– Study examined only non-occupational exposures

    • Review of full papers – Risk Effects– No data on the magnitude of any risk effects– No data from which risk effects were calculable

  • 9

    ABSTRACTS

    Discardn = 324

    Results: Literature Review

    TITLESn = 651

    Includen = 13

    Discardn = 99

    FULL PAPERSn = 112

    Discardn = 215

    n = 327

    Included Studies: Overview

    • 13 original articles – Andersen & Gaardboe 1993 – Svendsen et al 2004a– Chiang et al 1993 – Svendsen et al 2004b– Stenlund et al 1993 – Miranda et al 2005

    F t & A d 1999 W t l 2005– Frost & Andersen 1999 – Werner et al 2005– Kaergaard & Andersen 2000 – Melchior et al 2006– Punnett et al 2000 – Walker-Bone et al 2006– Frost et al 2002

    • 12 studies– Kaergaard & Andersen 2000 – Frost et al 2002

    Included Studies: Overview

    • Different study designs– Cross-sectional n = 10– Case-control n = 1– Cohort n = 2

    • Location– Northern Europe n = 8– Europe other n = 2– USA n = 2– Elsewhere n = 1

    Included Studies: Overview

    • Different populations– Sewing machine operators – Automobile industry– Fish processing – Machinists– Construction – House painters

    Sl ht h Offi k– Slaughterhouse – Office workers– Chemical factory – General population

  • 10

    Included Studies: Outcomes

    • Shoulder pain with physical findings

    • Rotator cuff syndrome / Rotator cuff disorder

    • Shoulder tendinitis / Chronic rotator cuff tendinitis• Shoulder tendinitis / Chronic rotator cuff tendinitis

    • Shoulder impingement syndrome

    • Rotator cuff tendinitis and / or myofascial pain syndrome

    • Supraspinatus tendinitis

    Included Studies: Exposures

    • Exposures– Binary– Cumulative exposure

    • Months / Years

    Proportion– Proportion• Job cycle• Maximum voluntary contraction

    • Exposure measurement– Questionnaire / Interview– Sub-group measurement– Sub-group observation / video

    Contributory Evidence

    • High quality cohort studies, self-report outcome

    • Papers: n = 7

    • Reported outcomes– Shoulder pain alone– Shoulder pain with or without neck / upper limb pain

    Occupational Exposures

    • Physical exposures– Position of upper limb– Manual handling / force– Repetitive tasks

    Oth h i l– Other physical exposures

    • Psychosocial exposures

  • 11

    Position of Upper Limb

    • Papers: n = 6

    • Conclusion– Moderate [++] to Strong [+++] evidence to suggest a causal [ ] g [ ] gg

    relationship between working with arms in an elevated position and rotator cuff disease / biceps tendinitis

    Position of Upper Limb

    10.0

    r Dis

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    Walker-Boneet al 2006

    10.0

    r Dis

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    Walker-Boneet al 2006

    Svendsen et al 2004b10.0

    r Dis

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    Svendsen et al 2004b Miranda et al 2005Walker-Boneet al 2006

    0.1

    1.0

    OR

    (95%

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    of S

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    1hr

    Work with handsabove shoulders

    0.1

    1.0

    OR

    (95%

    CI)

    of S

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    der

    1hr

    Work with handsabove shoulders

    90o (months)

    >24

    0.1

    1.0

    OR

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    CI)

    of S

    houl

    der

    90o (months)

    >24 None 1-3 4-13 14-23 >23

    Duration (yrs) working with handabove shoulder >1hr per day

    1hr

    Work with handsabove shoulders

    Contributory Evidence

    • Provides evidence to support association

    • Miranda et al 2001– Working with arms above shoulderg

    • Harkness et al 2003– Working with hands above shoulder level– Lifting heavy weights above shoulder level

    Position of Upper Limb

    • Evidence to suggest a causal relationship– Moderate [++] to Strong [+++]– Consistent evidence across a number of studies in a number

    of different occupational environmentsSupported by high quality cohorts with subjective outcomes– Supported by high quality cohorts with subjective outcomes

    • Insufficient studies presenting robust exposure-response data– Not possible to inform exposure standards

    • Degrees of elevation• Time with arms elevated

    – Not possible to identify ‘safe’ limits of exposure

  • 12

    Occupational Exposures

    • Physical exposures– Position of upper limb– Manual handling / force– Repetitive tasks

    Oth h i l– Other physical exposures

    • Psychosocial exposures

    Manual Handling / Force

    • Papers: n = 8

    • Conclusion– Moderate evidence [++] to suggest a causal relationship [ ] gg p

    between manual handling / occupational force requirements and rotator cuff disease / biceps tendinitis

    Manual Handling / Force

    10.0

    r Dis

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    Chiang et al 199310.0

    r Dis

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    Miranda et al 2005Chiang et al 199310.0

    r Dis

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    Miranda et al 2005Chiang et al 1993 Frost et al 2002

    0.1

    1.0

    OR

    (95%

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    of S

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    No Yes

    Upper limb force-ful movements

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    None 1-3 4-13 14-23 >23

    Duration (yrs) of frequent lifting:>5kg, >2 time / min, >2hrs / day

    No Yes

    Upper limb force-ful movements

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    None 1-3 4-13 14-23 >23

    Duration (yrs) of frequent lifting:>5kg, >2 times / min, >2hrs / day

    No Yes

    Upper limb force-ful movements

    Ref 10%

    Manual Handling / Force

    • Evidence not consistent

    • Werner et al 2005– No difference in peak force requirement between cases

    (persons with incident shoulder tendinitis) and controls

    • Svendsen et al 2004a– Supraspinatus tendinopathy– Lifetime shoulder force requirements

    • Low OR: 1.0• Medium 1.2 (0.5-3.2)• High 0.7 (0.3-1.7)

  • 13

    Contributory Evidence

    • Provides evidence to support association

    • Harkness et al 2003– Lifting weightsg g– Carrying weights on one shoulder

    • Andersen et al 2003– Force requirements

    Manual Handling / Force

    • Evidence to suggest a causal relationship– Moderate [++]– A number of studies have observed a positive relationship

    between this exposure and outcomeSupportive contributory evidence– Supportive contributory evidence

    • Not all studies have provided consistent evidence

    Occupational Exposures

    • Physical exposures– Position of upper limb– Manual handling / force– Repetitive tasks

    Oth h i l– Other physical exposures

    • Psychosocial exposures

    Repetitive Tasks

    • Papers: n = 5

    • Conclusion– Weak evidence [+] to suggest a causal relationship between [ ] gg p

    repetitive tasks and rotator cuff disease / biceps tendinitis

  • 14

    Repetitive Tasks

    10.0

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    Chiang et al 199310.0

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    Chiang et al 1993 Frost et al 200210.0

    r Dis

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    Frost et al 2002 Frost et al 2002Chiang et al 1993

    0.1

    1.0

    OR

    (95%

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    of S

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    No Yes

    Repetitive movements of arm

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    No Yes

    Repetitive movements of arm

    No Yes

    Repetitive manualhandling

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    No Yes

    Repetitive manualhandling

    None 15No Yes

    Repetitive movements of arm

    Contributory Evidence

    • Inconsistent

    • Andersen et al 2003– Shoulder movements (per minute)(p )– Increase in likelihood of shoulder pain

    • Harkness et al 2003– Repetitive arm / wrist movements– No increase in likelihood of shoulder pain

    Repetitive Tasks

    • Evidence to suggest a causal relationship– Weak [+]– Evidence across a number of studies suggesting a positive

    relationshipInconsistent supporting evidence using subjective outcomes– Inconsistent supporting evidence using subjective outcomes

    – Cannot rule out bias or confounding – particularly by manual handing / force requirements

    • Insufficient studies examining repetition and force requirements independently

    Combination: Force & Repetition

    10.0

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    Frost et al 2002

    0.1

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    of S

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    High freq,Low force

    Low freq,High force

    High freq,High force

    Referencegroup

    Low freq,Low force

  • 15

    Interaction: Force * Repetition

    10.0

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    Chiang et al 199310.0

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    Chiang et al 199310.0

    r Dis

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    Chiang et al 199310.0

    r Dis

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    Chiang et al 1993

    0.1

    1.0

    OR

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    of S

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    Forceful movementsof upper arm

    No Yes No Yes

    Repetitive movementsof upper arm

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    Forceful movementsof upper arm

    No Yes No Yes

    Repetitive movementsof upper arm

    Yes

    Interaction offorce * repetition

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    Forceful movementsof upper arm

    No Yes No Yes

    Repetitive movementsof upper arm

    Yes

    Interaction offorce * repetition

    Expected

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

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    Forceful movementsof upper arm

    No Yes No Yes

    Repetitive movementsof upper arm

    Yes

    Interaction offorce * repetition

    Expected Actual

    Interaction: Force * Repetition

    • Evidence to suggest a causal relationship– Insufficient [0]– Data is sparse– No contributory evidence

    Occupational Exposures

    • Physical exposures– Position of upper limb– Manual handling / force– Repetitive tasks

    Oth h i l– Other physical exposures

    • Psychosocial exposures

    Occupational Vibration

    • Papers: n = 2

    • Miranda et al 2005– Working with vibrating tool,

    >2hrs /day

    • Stenlund et al 1993– Per tertile increase in work-

    life exposure

    • Conclusion– Insufficient evidence [0] to suggest a causal relationship

    between occupational vibration and rotator cuff disease / biceps tendinitis

    • None OR: 1.0• 1-3yrs 0.6 (0.1-4.6)• 4-13yrs 2.5 (1.0-5.9)• 14-23yrs 3.5 (1.5-7.8)• >23yrs 1.4 (0.5-4.4)

    • Right shoulder 1.9 (1.0-3.4)• Left shoulder 2.5 (1.1-5.9)

  • 16

    Occupational Driving

    • Papers: n = 1

    • Miranda et al 2005– Driving >4hrs / day, >3

    months / year

    • Conclusion– Insufficient evidence [0] to suggest a causal relationship

    between occupational driving and rotator cuff disease / biceps tendinitis

    • None OR: 1.0• 1-3yrs 2.6 (0.9-7.2)• 4-13yrs 1.4 (0.6-3.5)• 14-23yrs 2.7 (1.1-6.4)• >23yrs 1.1 (0.4-3.0)

    Occupational Exposures

    • Physical exposures– Position of upper limb– Manual handling / force– Repetitive tasks

    Oth h i l– Other physical exposures

    • Psychosocial exposures

    Work Demands

    10.0

    r Dis

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    Miranda et al 200510.0

    r Dis

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    Miranda et al 2005 Svendsen et al 2004b10.0

    r Dis

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    Miranda et al 2005 Svendsen et al 2004b Walker-Boneet al 2006

    0.1

    1.0

    OR

    (95%

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    of S

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    Low High

    0.1

    1.0

    OR

    (95%

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    of S

    houl

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    Low High Low High

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

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    Low High Low High No Yes

    Control over Work / Job Strain

    10.0

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    Svendsen et al 2004b10.0

    r Dis

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    Svendsen et al 2004b Walker-Boneet al 2006

    10.0

    r Dis

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    Kaergaard andAndersen 2000

    Svendsen et al 2004b Walker-Boneet al 2006

    0.1

    1.0

    OR

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    of S

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    High Low

    Control

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

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    High Low

    Control

    Yes No

    Control

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

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    High Low

    Strain

    High Low

    Control

    Yes No

    Control

  • 17

    Perceived Support

    10.0

    r Dis

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    Kaergaard andAndersen 2000

    10.0

    r Dis

    orde

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    Kaergaard andAndersen 2000

    Walker-Boneet al 2006

    10.0

    r Dis

    orde

    r

    Kaergaard andAndersen 2000

    Walker-Boneet al 2006

    Svendsen et al 2004b

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    High Low

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    High Low Yes No

    0.1

    1.0

    OR

    (95%

    CI)

    of S

    houl

    der

    High Low Yes No High Low

    Contributory Evidence

    • Inconsistent findings– Work demands– Control over work

    • Evidence

    • Perceived (lack of) support– Work not entirely consistent– Overall suggestion of

    positive association– Small effect• Evidence

    – No effect– Effect of modest and

    non-significant magnitude

    • Conclusion– Insufficient [0] evidence to suggest a causal relationship between

    most psychosocial exposures and rotator cuff disease / biceps tendinitis

    – Perceived lack of support: weak evidence [+]

    Other Issues

    Other Issues

    • Sensitivity analysis

    • Gender

    • Prognosis

  • 18

    Sensitivity Analysis

    • Stringent outcome criteria

    • Six of 13 studies may have included – Neck or upper arm pain onlypp p y– Pain on palpation alone– Myofascial pain syndrome– Adhesive capsulitis

    • One study may have identified persons with pathology, but without pain

    Query impacton findings ?

    Sensitivity Analysis

    • Diagnostic inaccuracy – bias towards the null?

    • Where an exposure is a risk factor for a disorder other than those of specific interestother than those of specific interest– Risk estimates may be augmented by the inclusion of

    persons with competing diagnoses

    • Exclusion of studies

    Sensitivity Analysis

    ++ / +++Upper arm elevation

    Sensitivity analysis

    Main findingsExposure

    + / 0Psychosocial factors

    0Other physical / mechanical

    +Repetitive tasks

    ++Manual handling / force

    .

    .

    .

    Other Issues

    • Sensitivity analysis

    • Gender

    • Prognosis

  • 19

    Gender Differences

    Physical exposures

    • Papers: n = 2

    • Effect of similar magnitude in men and women– Working in a manual occupation– Working with hands above shoulder level– Working with hands away from body / behind trunk

    Gender Differences

    Psychosocial exposures

    • Papers: n = 1

    • Effect of similar magnitude in men and women– Work demands– Threat of being bullied or mentally abused

    • Burnout– Men: Doubling in odds of symptoms (non-significant)– Women: Halving of odds of symptoms (non-significant)

    Other Issues

    • Sensitivity analysis

    • Gender

    • Prognosis

    Prognosis

    • Parallel identification and review of literature– Bibliographic databases– Outcome and exposure information– Additional key-words

    Prognosis / disability / recovery / sickness absence / consequences• Prognosis / disability / recovery / sickness absence / consequences

    • Papers: n = 3

    • Conclusion– Insufficient evidence [0] to suggest any causal relationships– Favourable outcome in large proportion of patients– Duration of treatment varies between individuals

  • 20

    Summary

    Summary

    EvidenceExposure

    ++ / +++Working with arms in an elevated position *

    ++Manual handling / occupational force requirement

    +Repetitive tasks (independent of force)

    0Other physical / mechanical exposures

    * Robust to exclusion of studies with potential diagnostic inaccuracy

    *

    Summary

    EvidenceExposure

    +Perceived (lack of) support at work

    0Perceived occupational demands

    0Perceived (lack of) control at work

    0Other psychosocial factors

    0Factors relating to prognosis

    Limitations of Current Research

    • Paucity of high quality prospective cohort studies

    • Few studies presenting robust exposure-response data– Not possible to inform exposure standards– Not possible to identify ‘safe’ limits of exposure

    • Insufficient evidence to be able to distinguish– Exposures that lead to pathological changes– Exposures that aggravate symptoms that originate from pre-

    existing shoulder pathology

  • 21

    Acknowledgements

    • University of Aberdeen– Dr Nirupa Pallawatte– Dr Ashraf El-Metwally– Dr Finlay Dick– Professor Gary Macfarlane

    • SC-DSOEM– Dr Susanne Svendsen– Dr Johan Andersen– Dr Sigurd Mikkelsen

    y– Professor David Reid • External Review

    – Dr Alex Burdoff– Mr Jens Ivar Brox

    Methods: Assessing Study Quality

    High ScoreLow ScoreRatingCriteria

    Cohort study; long follow-up

    Cross-sectional study

    Range: 0 – 3 ObjectiveStudy design

    >1000 participants85% participation

  • 22

    Methods: Assessing Study Quality

    High ScoreLow ScoreRatingCriteria

    Adjustment for 4+ key confounders

    No adjustment for key confounders

    Range: 0 – 3 ObjectiveConfounding

    Blinding; robust methodsNo blinding

    Range: 0 – 2 SubjectiveBlinding

    Objective / 2+ observers / video

    Subjective assessment

    Range: 0 – 3 Subjective

    Exposure measurement

    Exposures on quantitative scale

    Dichotomous exposures

    Range: 0 – 3 Objective

    Exposure-response data

    Full clinical examPoor quality measurementRange: 0 – 3 Subjective

    Outcome measurement

    Reviewer 2Reviewer 1

    TITLESn = 651

    Review of Titles

    Reviewer 3(added n = 80)

    Review abstractsn = 327

    Discardn = 324

    Agree to rejectn = 241

    Agree to acceptn = 247

    Disagreen = 163

    Reviewer 2Reviewer 1

    ABSTRACTSn = 327

    Review of Abstracts

    Reviewer 3(added n = 15)

    Review full papersn = 112

    Discardn = 215

    Agree to rejectn = 178

    Agree to acceptn = 97

    Disagreen = 52

    Reviewer 2Reviewer 1

    FULL PAPERSn = 112

    Review of Full Papers

    Reviewer 3(added n = 1)

    Includen = 13

    Discardn = 99

    Agree to rejectn = 78

    Agree to acceptn = 12

    Disagreen = 22

  • 23

    Results: Study Quality

    • Maximum quality rating in all areas n = 0

    • High quality n = 7– Maximum or maximum-1– At least five criteria

    • Recent studies– Higher quality