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Management of Vertebral Compression Fractures - PowerPoint

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					How Poor Quality Densitometry
    Affects Patient Care


     E. Michael Lewiecki, MD, FACP, FACE
     New Mexico Clinical Research & Osteoporosis Center
                      Albuquerque, NM
     Survey of ISCD Members
         on DXA Quality
• Online survey sent to 3488 clinicians
  and 2362 techs in mid 2006
• Series of questions on quality of DXA
  studies and reports from other facilities
• 743 (21%) clinicians and 754 (32%)
  techs responded


                       Lewiecki EM et al. J Clin Densitom. 2006;9:388-392.
Perceived Frequency of Incorrect
         DXA Reports




Responses of 690 ISCD clinician members
                                          Lewiecki EM et al. J Clin Densitom. 2006;9:388-392.
Perceived Impact of Poor Quality
 DXA Reports on Patient Care




Responses of 726 ISCD clinician members
                                          Lewiecki EM et al. J Clin Densitom. 2006;9:388-392.
                Implications
• Survey
  – Variability in quality of DXA acquisition, analysis,
    and interpretation
  – Adverse consequences on patient care

• Possible solutions
  – Education and training are likely to improve clinical
    outcomes
  – Documentation of proficiency in bone
    densitometry may be a useful quality indicator:
    certification, accreditation

                             Lewiecki EM et al. J Clin Densitom. 2006;9:388-392.
   How can poor quality BMD
    testing harm patients?

          Harm                         Cause
Expense               Unnecessary treatment, change in
                      treatment, testing, fracture
Side effects          Unnecessary or wrong treatment
Anxiety               Wrong diagnosis of osteoporosis
False reassurance     Wrong diagnosis of normal
Denial of insurance   Wrong diagnosis of osteoporosis
Disability/Death      Effective treatment not given
   Categories of Potential Errors
• Pre-testing
  – Deciding when to test
  – Selecting the right technology
• Testing
  – Quality control
  – Acquisition
  – Analysis
• Post-testing
  – Interpretation
  – Reporting

      Focus: adverse clinical consequences
  Mistakes Ordering a BMD Test
• Testing patient when it is unlikely to change
  clinical management
   – Misappropriation of limited healthcare resources
   – Ex.- DXA on healthy premenopausal woman

• Not testing patient when it is likely to change
  clinical management
   – Missed opportunity to identify patient who may
     benefit from therapy
   – Ex.- Not doing DXA on 60 year-old man on
     chronic glucocorticoids
   Categories of Indications for
         BMD Testing
• Population screening
  – Testing everyone in a high risk group
  – Ex.- women age 65 and older
• Case-finding (risk-based)
  – Testing high risk individuals
  – Ex.- patient on long-term glucocorticoids
• Treatment-related
  – Testing as a baseline or follow-up of treatment
  – Ex.- monitoring therapy
Official Position
                    Indications for BMD Testing
     • Population screening
            – Women aged 65 and older
            – Men aged 70 and older

     • Case-finding (risk-based)
            – Postmenopausal women under age 65 with risk factors
            – Women during the menopause transition with clinical risk factors
              for fracture, such as low body weight, prior fracture or high risk
              medication use
            – Men under age 70 with risk factors for fracture
            – Adults with a fragility fracture
            – Adults with a disease or condition associated with low bone mass
              or bone loss
            – Adults taking medications associated with low bone mass or
              bone loss


                                                 Baim S et al. J Clin Densitom. 2008; 11:75-91.
Official Position
                    Indications for BMD Testing



     • Treatment-related
            – Anyone being considered for pharmacologic therapy
            – Anyone being treated, to monitor treatment effect
            – Anyone not receiving therapy in whom evidence of bone loss
              would lead to treatment
          Women discontinuing estrogen should be considered for
          bone density testing according to the indications listed above.




                                                 Baim S et al. J Clin Densitom. 2008; 11:75-91.
      Wrong Tool for the Job:
       QUS for Diagnosis
• 66 year-old healthy Caucasian woman
  has heel QUS at shopping mall
• Risk factor: mother had hip fracture at
  age 85 after a fall
• QUS T-score = -1.0
• She is told bone density is normal and
  that no further testing is necessary
      Wrong Tool for the Job:
       QUS for Diagnosis
• Problems
  – QUS cannot be used for diagnosis
  – QUS T-scores are usually better than DXA
• Possible consequences
  – False reassurance
  – Underestimation of fracture risk
  – Treatment not considered
FN DXA T-score = -2.3 with 27% 10-year probability of major
osteoporotic fracture: meets NOF guideline for drug therapy
      Wrong Tool for the Job:
        QCT for Diagnosis
• 73 year-old Hispanic woman has QCT
  of spine
• No clinical risk factors for fracture
• QCT T-score = -2.5
• She is told she has osteoporosis and
  prescribed alendronate
     Wrong Tool for the Job:
       QCT for Diagnosis
• Problems
  – QCT cannot be used for diagnosis
  – QCT T-scores are usually worse than DXA
• Possible consequences
  – Diagnosis may be incorrect
  – Overestimation of fracture risk
  – Unnecessary treatment may be given
FN DXA T-score = -1.8 with low probability of osteoporotic
fractures: does not meet NOF guideline for drug therapy
Official Position
                    Non-central DXA Devices

              T-scores from measurements other than
              DXA at the femur neck, total femur,
              lumbar spine, or one-third (33%) radius
              cannot be used according to the WHO
              diagnostic classification because those
              T-score are not equivalent to T-scores
              derived by DXA

                                   Baim S et al. J Clin Densitom. 2008; 11:75-91.
 BMD Testing Technologies
                DXA    pDXA QUS QCT pQCT
Diagnosis       *     **    -     -      -
Fracture Risk                          
FRAX            ***    -      -    -      -
Monitoring Rx          -     -            -
Radiation       ++      +     o    +++     ++
Cost            ++      +     +    +++     ++


        *LS, FN, TH, 33%R; **33%R; ***FN
        Quality Control:
Assessment of Instrument Calibration
• Methods
  – Do periodic phantom scans
  – Plot and review calibration data
  – Take corrective action when necessary
• Non-compliance may cause BMD
  measurement to be higher or lower than actual
• Consequences are possible errors in:
  – Diagnostic classification
  – Assessment of fracture risk
  – Treatment decisions
              Quality Control Chart:
               Normal Calibration
Phantom BMD




                                           Upper Limit
                                       .

                                           Average

                                           Lower Limit




                     Time
                    Quality Control Chart:
                      Calibration Drift
Phantom BMD




                                                                    Upper Limit
                                                                .

                                                                    Average

                                                                    Lower Limit




                                   Time

              Example: Aging of equipment, local environmental changes
                      Quality Control Chart:
                        Calibration Shift
Phantom BMD




                                                                    Upper Limit
                                                                .

                                                                    Average

                                                                    Lower Limit




                                    Time

              Example: Replacement of major component, moving instrument
           Quality Control:
        Precision Assessment*
• Method: 2 or more scans on series of
  patients to determine reproducibility of
  BMD measurements
• Without precision assessment, it cannot be
  known whether an apparent BMD change
  is real or a measurement error
• If insignificant BMD changes are reported
  as real, then …
  – Harmful or expensive treatment decisions
  – Unnecessary or expensive referral or testing

                      *Assessment of “technologist calibration”
Official Position
                    Precision Assessment

         • Each DXA facility should determine its
           precision error and calculate the LSC
         • The precision error supplied by the
           manufacturer should not be used
         • Every technologist should perform an in
           vivo precision assessment using
           patients representative of the clinic’s
           patient population

                                 Baim S et al. J Clin Densitom. 2008; 11:75-91.
           Quality Control:
Standard Operating Procedures (SOPs)
 • Reference manual for operating a bone
   densitometry facility
 • Often includes:
    – Procedures for radiation safety
    – Documentation of regulatory compliance
    – Instrument calibration assessment and monitoring
    – Staff training standards and documentation
    – Routine for patient scheduling and education
    – Precision assessment standards
    – Facility procedures for measuring additional skeletal
      sites and doing VFA
    – Much more
        Acquisition Mistakes
•   Incorrect demographic information
•   Improper patient positioning
•   Removable artifacts not removed
•   Wrong scan mode
•   Invalid skeletal site
•   Fat panniculus issues
Poor Hip Position- Abducted




          Faxed Image
Study of BMD with Femur Angulation
   using Bilateral Foot Positioner
• 200 patients had bilateral
  hip BMD on GE Lunar
  Prodigy using bilateral foot
  positioner
• 85% of patients had femur
  angles  6°
• No correlation between
  femur angles and left to
  right BMD differences
• Small degrees of
  angulation may not
  significantly affect hip BMD
                                   7° Abduction             4° Adduction



                                 Wong JC et al. J Clin Densitom. 2005;8:472-475.
Differences in Leg Rotation
 Study on Effect of Leg Rotation
          on Hip BMD
• 50 women volunteers in Sri Lanka tested on
  Norland Eclipe XR with customary leg rotation,
  10° excess internal rotation, and 10° excess
  external rotation
• Excess internal rotation decreased BMD: mean
  0.009 at FN (P <0.001), > LSC at FN in 12% of
  patients
• Excess external rotation increased BMD: mean
  0.005 (P = 0.119), > LSC at FN in 8%
• Malrotation may be a confounding factor in
  interpreting serial BMD tests

                       Lekamwasam S et al. J Clin Densitom. 2003;6:331-336.
Poor Spine Position- Tilted
Tablets (calcium, multivitamin) in Pocket
           Chromium Tablets

Baseline




Next Day
    Study of Effect of Calcium
  Tablets on Lumbar Spine BMD
• Phantoms and volunteers
  tested with calcium tabs over
  lying bone, soft tissue, or
  both, using 3 different models
  of Hologic instruments
• Single tablet had little effect
  on L1L4 BMD
• Substantial effect on BMD of
  single vertebral body (as
  much as 12.6% increase)
• Undissolved calcium tablet
  may alter diagnostic
  classification and precision if
  fewer than 4 vertebral bodies
  analyzed


                                    Kendler DL et al. J Clin Densitom. 2006;9;97-104.
   Study on Effect of Common
 Artifacts on Lumbar Spine BMD
• Cadaver study with high
  BMD and low BMD spines
  using variety of artifacts
  with Hologic Discovery W
• Bra wires and calcium
  tablets affected BMD for
                                          Bra Wires
  low BMD spine                                             Calcium Tab

• GB clips and gallstone
  had no effect on either
  spine
• No artifacts affected BMD
  for high BMD spine

                                          GB Clips           Gallstone


                               Morgan SL et al. J Clin Densitom. 2008;11:243-249.
Scan Mode Makes a Difference
Same Obese Patient (BMI 36.6), Different SMs (Hologic)




  Fast Array Mode (30 sec.)        Array Mode (60 sec.)
  L1-L4 BMD = 0.829 g/cm2     L1-L4 BMD +0.034 g/cm2 (>LSC)
             Fat Panniculus




 12-4-03                   12-9-03

    TH T-score = 2.5          TH T-score = 1.2
    FN T-score = -2.4        FN T-score = -0.3

Panniculus Not Retracted   Panniculus Retracted
          Analysis Mistakes
•   Analyzing structurally abnormal bones
•   Poor identification of bone edges
•   Mislabeling of vertebral bodies
•   Poor placement of ROI
Severe Scoliosis
Structural Abnormality
              Level   T-score
               L1      -1.3

               L2      +2.8

               L3      +3.1

               L4      -0.6

              L1-L4    +1.1
 Poor Neck Box Placement




FN T-score = -3.2   FN T-score = -3.0
              Case Study
• 65 year-old man has osteoporosis (L1-L4 T-
  score = -3.3) associated with hypogonadism
• Treatment with alendronate resulted in a
  significant BMD increase at L1-L4, but a
  subsequent DXA showed a significant BMD
  loss
• He is referred for evaluation of non-response
  to therapy
• What do you do?
         What do you do?
A. Change therapy to an injectable
   bisphosphonate
B. Stop alendronate and start teriparatide
C. Order lab studies to evaluate for
   factors contributing to bone loss
D. Other
          Lumbar Spine Scans




    Baseline          Follow-up #1     Follow-up #2
L1-L4 = 0.729 g/cm2   +0.038 (+5.3%)   -0.037 (-5.1%)
              Diagnosis
• Mislabeled vertebral bodies
• Re-analysis of last study with correctly
  labeled vertebral bodies showed stable
  BMD since the previous study,
  representing a good response to
  therapy
• Recommendation: no change in therapy
          Interpretation Errors
• Misapplication of guidelines, standards, tools
  –   WHO diagnostic criteria
  –   FRAX
  –   NOF intervention thresholds
  –   ISCD Official Positions
• Invalid comparison of serial DXA studies
 Good Report or Bad Report?
• Actual report
   – L-spine measurements range from T score of -1.6 at
     L2 to -1.4 at L4
   – Left hip measurements range from T score of -2.7 for
     Ward’s triangle to -1.2 at trochanter
   – Impression: osteoporosis of left hip, osteopenia of
     spine
• Bad report
   – Wrong diagnosis: Don’t use Ward’s area
   – Don’t cherry pick vertebral bodies
   – Don’t make more than one diagnosis
   – Should be T-score not T score
 Good Report or Bad Report?
• Actual report
  – 62 year-old Asian woman with FN T-score =
    -2.6 woman has been on alendronate for 8
    years
  – Based on FRAX, the 10-year probability of
    major osteoporotic fracture is 9.1% and 1.8%
    for hip fracture
• Bad report
  – FRAX does not apply to treated patients
 Good Report or Bad Report?
• Actual report
  – 82 year-old Black male smoker has FN T-
    score = -2.3
  – FRAX shows a 10 hip fracture risk of 3.0%
  – Treatment is indicated according to the NOF
    Guide
• Bad report
  – FRAX Patch not used to convert T-score
  – Repeat calculation with FRAX Patch shows
    that treatment not indicated with NOF guide
   73 Year-old Woman
  Referred for Bone Loss
   11/19/01                                 10/17/02




FN BMD = 0.626                       FN BMD = 0.581

        Reported bone loss = 0.045 (7.2%)


Problems: Invalid comparison of left
hip with right hip; different instruments
 Potential Missed Diagnosis:
Metastatic Prostate Carcinoma
      Premenopausal Woman
          with Low BMD
• Healthy premenopausal 29 year-old
  female dentist with no history of fractures
• Free heel QUS at health fair shows T-
  score = -1.2
• Physician orders DXA that shows L1-L4 T-
  score = -2.5
• Osteoporosis is diagnosed and she is
  started on alendronate
• Three years later she applies for disability
  insurance
    Economic Consequences:
     Premenopausal Woman
• Disability insurance coverage is denied
  due to diagnosis of osteoporosis
• Evaluation by a consulting physician
  concludes that she does not meet criteria
  for a diagnosis of osteoporosis and that
  fracture risk is low
• Alendronate is stopped and a letter of
  explanation is sent to insurance company
• With reconsideration, insurance is again
  denied
     ISCD Official Positions
• Benefits
  – Standardization of testing methodologies
  – Very helpful in clinical practice
  – Focus attention on areas in need of study
• Limitations
  – Evidence often limited
  – Applicability may vary by location
                        FRAX
• Benefits
   – Quantitative assessment of fracture risk
   – Greater clinical utility than RR
• Limitations
   –   BMD input is FN only
   –   “Dose-effect” of risk factors not considered
   –   Important risk factors not included
   –   Limited to certain ethnicities in USA
   –   May over- or under-estimate actual fracture risk
   –   Does not apply to treated patients
   –   Website inconsistent and inconvenient
                NOF Guide
• Benefits
  – Improved patient selection for treatment
  – Expanded applicable population
  – Better use of limited healthcare resources
• Limitations
  – Based on numerous assumptions
  – Apparent internal conflicts
  – May identify some patients for treatment when
    little or no evidence of benefit (T-score > -1.5)
                  Summary
• Poor quality bone densitometry is common
• Consequences include inappropriate patient
  management decisions, poor clinical outcomes,
  and unnecessary healthcare expenses
• Thorough understanding of technological
  standards, fracture risk assessment, and treatment
  guidelines is necessary for good quality control,
  acquisition, analysis, interpretation, and reporting
• Education and training are pathways to improving
  quality
• Certification and accreditation may provide
  assurance of quality

				
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