BACK PAIN - CHRONIC ISSUES

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					BACK PAIN - CHRONIC
      ISSUES
        David Borenstein, MD
   Clinical Professor of Medicine
Arthritis and Rheumatism Associates
The George Washington University
            Medical Center
           Washington, DC
         Chronic Low Back Pain
Issues for Discussion
   1. Define the forms of chronic low back pain and
     its prevalence (Is it frequent and important
     enough to study?)
   2. Will patient selection including etiology and
     severity influence the performance of drugs in
     development? (Is it possible to identify and
     separate the individuals with back pain?)
   3. Which are the appropriate outcome measures?
     (Can improvements in back pain related to
     therapy be determined?)
         Chronic Low Back Pain
Issues for Discussion
   4. Will a general indication be useful for different
     labeling claims? (somatic v. neuropathic v.
     chronic headache)
   5. Chronic low back pain - serve as a measure of
     efficacy for a general chronic pain indication or
      specific indication for chronic low back pain
     alone
WHAT IS CHRONIC
 LOW BACK PAIN
       And
ITS PREVALENCE?
        LOW BACK PAIN -
          DEFINITION
Pain that occurs in an area with boundaries
  between the lowest rib and the crease of the
  buttocks
  Chronic Low Back Pain
• Duration greater than 3 months
• Pain that persists longer than the
   expected time period for healing
     Epidemiology of Low Back Pain
• 20% of the US population develops back
  pain yearly
• Back pain -second most common cause of
  disability in the US (leading cause among
  men) accounting for 16.5% of the total
  disabilities in > 18 yo in 1999
• Workers’ compensation 1986-1996 - > 1
  year 8.8% of claims - 64.9%-84.7% of
  annual costs
___________________________________
CDC. MMWR 2001;50:120-125
Hashemi L et al: J Occup Environ Med 1998;40:1110-1119
   Natural History of Low Back Pain
443 LBP subjects postal questionnaire 12 months
15 general practices Amsterdam, Netherlands
269 completed survey - less pain answered less often
7 weeks-median time to recover
At 12 weeks-35%, 52 weeks-10% had LBP
75% had 1 or more relapses during study
Pain and disability was less during relapses
Time to relapse-median 7 weeks, duration-median 6
  weeks
__________________________________________
van den Hoogen et al: Ann Rheum Dis 1998;57:13-19
      Low Back Pain - Disorders
       Mechanical                       Referred
       Rheumatologic                    Hematologic
       Infectious                       Neurologic
       Neoplastic                       Psychiatric
       Endocrinologic                   Miscellaneous
                         (N > 60)

_____________________________________
Borenstein D, Wiesel S, Boden S: Low Back Pain: Medical Diagnosis and
   Comprehensive Management. 1995
      Low Back Pain - Disorders
Mechanical - 85% of all low back pain
  •   Muscle, ligament, tendon strain
  •   Discogenic disorders including herniated disc
  •   Apophyseal joint arthritis
  •   Spinal stenosis
  •   Spondylolysis, spondylolisthesis
  •   Scoliosis
     Sources of Low Back Pain
• Superficial somatic - skin
• Deep somatic - muscle, joint, tendon, bursa,
  fascia
• Radicular - nerve root
• Visceral referred - sympathetic afferents
• Neurogenic - mixed motor sensory nerves
• Psychogenic - cerebral cortex
            Pain Intensity
• Minimal - mentioned in passing, normal
  function
• Mild - component of symptoms, mild
  dysfunction
• Moderate - major component of symptoms,
  alters function
• Severe - the disease symptom,
  incapacitating function
              Diagnostic Evaluation
    Diagnosis of low back pain is unspecified
              in 80% of patients

_________________________________________
Dillane JB et al: Acute back syndrome: a study from general practice.
  BMJ. 1966;2:82-84
Rowe ML: Low back pain in industry: a position paper. J Occup Med
  1969;11:161-169
White AA, Gordon S. Symposium on Idiopathic Low Back Pain.
  Mosby Co. 1982
            LOW BACK PAIN -
              DIAGNOSIS
• Specific diagnosis is possible
• Differentiation of muscle, joint,
  ligamentous structures
• Mechanical versus systemic disorders is
  possible
• Categorize by clinical symptoms
• Subtyping will improve therapy
_____________________________________
Abraham I, Killackey-Jones B: Arch Intern Med 2002;162:1442-1444
          LOW BACK PAIN -
            DIAGNOSIS
• Specific diagnosis is impossible
• Anatomic abnormalities in asymptomatic
  individuals
• Overutilization of imaging techniques
• Inconsistency of physical findings
• Non-specific therapy is effective
____________________________________
Deyo RA: Arch Intern Med 162:1444-1446, 2002
         LOW BACK PAIN -
           DIAGNOSIS
• Somatic v. neuropathic v. radicular pains
  can be differentiated
• Specific pain generators (individual joint or
  muscle) are difficult to identify but
  localization is not essential for effective
  therapy
  Chronic Back Pain - Outcome
           Measures
• Back specific function
• Pain
• Patient global satisfaction
Back Pain - Outcome Measures

    Back Specific Function

    Roland Morris Disability
     Questionnaire

    Oswestry Disability Index
 Back Pain - Outcome Measures
Roland-Morris Disability Questionnaire -
  function assessment
• 24 items from the Sickness Impact Profile
• Functions affected by back pain that day
• Scores added ( 0-no disability to 24 -
  maximum disability)
• Validated and reproducible instrument
___________________________________
Roland M, Morris R: Spine 1983;8:141-144
  Back Pain - Outcome Measures
Oswestry Disability Index - pain and function
  assessment
• 10 sections on various functions with 6
  levels of assessment
• Physical and social functions that day
• Scores added (0-no disability to 100-
  maximum disability)
• Validated and reproducible instrument
_____________________________________
Fairbank J, Pynsent P: Spine 2000; 25:2940-2953
 Back Pain - Outcome Measures
Pain Measurement
  SF-36 pain scale
  Visual analog scale (VAS)
  Brief Pain Inventory (BPI)
  Treatment Outcomes in Pain Survey (TOPS)
 Back Pain - Outcome Measures
Global Satisfaction
  Extremely, very, somewhat satisfied
  Mixed
  Somewhat, very, extremely dissatisfied
 Back Pain - Outcome Measures
           (Optional)
• General health status
  – SF-36
• Depression
  – Beck Depression scale
 Back Pain - Outcome Measures
• Instruments exist to measure the effect of
  drug interventions on chronic back pain for:
  –   function
  –   pain
  –   global satisfaction
  –   general health status
Chronic Low Back Pain Therapy
        - Multimodality

Back exercises - flexion and/or extension
Aerobic exercise
Medications
Counterirritant topical therapies
Stress management
 Chronic Low Back Pain - Medications
NSAIDs
Muscle relaxants
Analgesics
Antidepressants
Anticonvulsants
Alpha-2 adrenergic agonists
Miscellaneous

NONE ARE INDICATED FOR CHRONIC
 LOW BACK PAIN!
       Chronic Low Back Pain -
        Medications - NSAIDS
• Short half-life
   – acute exacerbations, quick onset
• Long half-life
   – sustained effect
• Cox - 2 inhibitors
   – equal efficacy - decreased toxicity

• van Tulder et al: Spine 2000;25:2501-2513
      Chronic Low Back Pain -
    Medications - Muscle Relaxants
•   Cyclobenzaprine
•   Orphenadrine
•   Metaxolone
•   Chlorzoxazone
•   Methocarbamol
     Chronic Low Back Pain -
     Medications - Analgesics
• Nonnarcotic
  – Acetaminophen
  – Tramadol
• Narcotic
  – Short acting
  – Long acting
  Case Study - Chronic Somatic
    Pain - Mild To Moderate
• 52 year old person - work-related
  myofascial injury
  – Treatment regimen
     •   Change of NSAID - diclofenac 100mg QD
     •   Maintain methocarbamol 750mg BID
     •   Diclofenac 50mg prn acute exacerbations
     •   maintain exercises program
  Case Study - Chronic Somatic
    Pain - Mild to Moderate
• 67 year old person - facet arthritis
  – Treatment regimen
     • Rofecoxib 25mg QD
     • Cyclobenzaprine 10 mg QHS
  Case Study - Chronic Somatic
   Pain - Moderate to Severe
• 72 year old person - s/p laminectomy with
  fractured screw
  – Treatment regimen
     •   Celecoxib 200mg BID
     •   Nortriptyline 50mg QHS
     •   Fentanyl patch 50 mcg
     •   Hydrocodone 5 mg prn
     Case Study - Chronic
 Neuropathic Pain - Moderate to
            Severe
• 42 year old person - traumatic neuropathy -
  sciatic nerve
  – Treatment regimen
     •   Ketoprofen - long acting - 200mg QD
     •   Gabapentin - 100mg TID
     •   Oxycodone - long acting - 40mg TID
     •   Hydrocodone - 7.5mg PRN
       Chronic Low Back Pain -
              Summary
•   Model for chronic pain
•   Outcome tools are available
•   Somatic pain is identifiable
•   Degree of pain - effect on study design
    – mild to moderate - single drug v. placebo
      (active comparator)
    – moderate to severe - stable multidrug regimen -
      flare with withdrawal