BACK PAIN - CHRONIC ISSUES

David Borenstein, MDClinical Professor of Medicine

Arthritis and Rheumatism AssociatesThe George Washington University

Medical CenterWashington, DC

Chronic Low Back PainIssues 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

AndITS 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;50:120-125Hashemi L et al: J Occup Environ Med 1998;40:1110-1119

Natural History of Low Back Pain443 LBP subjects postal questionnaire 12 months15 general practices Amsterdam, Netherlands269 completed survey - less pain answered less often7 weeks-median time to recoverAt 12 weeks-35%, 52 weeks-10% had LBP75% had 1 or more relapses during studyPain and disability was less during relapsesTime 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;2:82-84Rowe ML: Low back pain in industry: a position paper. J Occup Med

1969;11:161-169White 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 MeasuresOswestry 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 MeasurementSF-36 pain scaleVisual analog scale (VAS)Brief Pain Inventory (BPI)Treatment Outcomes in Pain Survey (TOPS)

Back Pain - Outcome Measures

Global SatisfactionExtremely, very, somewhat satisfiedMixedSomewhat, 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 extensionAerobic exerciseMedicationsCounterirritant topical therapiesStress management

Chronic Low Back Pain - MedicationsNSAIDsMuscle relaxantsAnalgesicsAntidepressantsAnticonvulsantsAlpha-2 adrenergic agonistsMiscellaneous

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