# Presentation: 373784

## 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