The Public Health Problem of Pain: Epidemiology and Phenomenology Rollin M. Gallagher, MD, MPH University of Pennsylvania School of Medicine Philadelphia Veterans Medical Center

“Pain is a more terrible lord of mankind than even death itself.” Albert S. Schweitzer, 1931 On the Edge of the Primeval Forest. New York: Macmillan, 1931:652 What is pain?

Most common reasons for under-treated PAIN ??? Attitude: Pain isn’t important Lack of Awareness and Knowledge: 1)Pain’s prevalence 2)Pain’s impact -On people and their families -On healthcare costs and on society 3)The pathophysiology of the disease of pain Lack of Good Training 1)The assessment of pain and pain co-morbidities 2)The use of evidence-based treatment algorithms

Pain’s prevalence and impact -75 million Americans with chronic or recurring pain -40% with moderate to severe impact on their lives -pain levels affect outcome of disease -National economy -$150 billion yearly: medical care, wage replacement, disability, etc -Businesses: -$61 billion yearly in lost productivity in working adults

Not all pain is the same: The pathophysiology of painful diseases Nociceptive pain Caused by activity in neural pathways in response to potentially tissue-damaging stimuli Neuropathic pain Initiated or caused by a primary lesion or dysfunction in the nervous system Postoperative pain Mechanical low-back pain Sickle cell crisis Arthritis Peripheral neuropathy Postherpetic neuralgia Neuropathic low-back pain CRPS Diabetic neuropathy Sports/exercise injuries CRPS = complex regional pain syndrome. Central post- stroke pain Trigeminal neuralgia R Gallagher, adapted from Portenoy RK et al. Pain Management: Theory and Practice. 1996

Defining Pain Arthritis Spinal Stenosis Failed Back Neuropathy DM,PHN,HIV,post CVA Cancer Pain Mechanisms Acute Chronic < episodic < persistent End of life

Nociceptive pain Caused by activity in neural pathways in response to potentially tissue-damaging stimuli Neuropathic pain Initiated or caused by a primary lesion or dysfunction in the nervous system EXAMPLES OF MIXED PAIN STATES 1)Postoperative pain Mastectomy Low back and neck surgery Pelvic surgery 2)Spine disease 3)Cancer (cured, in remission, metastatic) 4)Amputation pain 5)Pelvic pain and interstitial cystitis Inflammatory/Immunological /Neurophysiologic Mediation

Pain’s Impact: Issues and challenges Established effects (by research) of chronic pain Quality of life Physical functioning Ability to perform ADLs Work Psychological morbidity Fear, anger, suffering Sleep disturbances Loss of self-esteem Medical morbidity & consequences Accidents Medication effects Immune function Clinical depression

Pain’s Impact: Issues and challenges Established effects (by research) of chronic pain Mismanaged chronic pain is often a personal, biopsychosocial catastrophe! ….and is a huge public health problem. Social consequences Marital/family relations Intimacy/sexual activity Social role and friendships Societal consequences Health care costs Disability Lost workdays Business failures Higher taxes

If chronic pain is a biopsychosocial catastrophe and a huge public cost, how do you deliver clinical care that is driven by performance based, biopsychosocial outcomes? You start by understanding: - the causal models of disease - the mechanisms underlying these models - the biopsychosocial phenomenology of each unique disease population - the biopsychosocial formulation for each individual You then assess the characteristics of the care delivery system. Finally, you formulate and implement a goal-oriented management plan.

Back Pain Low back pain accounts for 75% of all chronic pain conditions (> OA, HA, migraine, FM, cancer pain) 50% of working-age report “back pain” symptoms each year Most common cause of disability in persons < 45 yo At any given time, 1% of US population is chronically disabled because of back problems and another 1% is temporarily disabled Courtesy of B. Todd Sitzman, MD, MPH

Back Pain Most common reason for office visits to orthopedic surgeons, neurosurgeons, pain medicine physicians Estimated total annual societal cost of back pain in the US is greater than $50 billion 22% of chronic back pain patients have changed doctors “at least 3 times” in search of pain relief The primary reasons why chronic pain patients change physicians is due to their doctor’s: »Attitude toward pain »Knowledge about pain »Ability to treat pain Courtesy of B. Todd Sitzman, MD, MPH

By Duration: Acute Recurrent Persistent When does acute pain become chronic? - laboratory changes indicating chronicity changes begin within minutes. - clinically, changes start happening soon after onset, often within 1-2 weeks. Problems in classifying pain By Intensity No pain -Mild -Moderate -Severe -Excruciating -Unbearable Is person X’s “10” the same as person Y’s “10” (or person Y’s “8”, “5”, or “3”)?

Problems in classifying pain By region: low back pain By anatomy - spine - muscles - kidneys Vertebral body Disk Facet joint Nerve Root Osteoporosis Fracture Tumor Spondylolisthesis Scoliosis Degenerated Annulus tear Herniation with or without fragment Arthritis Instability Inflammation Compression Avulsion BY PATHOLOGY

By Mechanism -Neuropathic -Nociceptive -Myofascial Problems in classifying pain Sensitization - peripheral - central Sympathetically mediated Nerve injury/damage (surgery, radiation, chemotherapy) Neuroma Neuralgias, Neuropathies Radiculopathies Deafferentation / Excitotoxicity Rebound headache Migraine headache Tissue injury Auto-immune disease Inflammation Infection Arthritis Cancer

Radiculopathy Definition: “Disturbance in the function of one or more nerve roots” Hallmark characteristic: “Pain in the presence of segmental nerve dysfunction” Described as shooting or electric shock-like Symptoms result from inflammation or compression of the nerve root May include both sensory and motor loss

Radiculopathy - Etiology Mechanical Stimulation: Common – disc bulge, herniation, fragmentation – contact with a facet joint osteophyte – ligamentum flavum thickening Less Common (serious) – infection, hematoma formation, tumor

Radiculopathy - Diagnosis 80% of adults over 55 years of age have degenerative disk changes by MRI and are often asymptomatic Jensen MC et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994, 331:69-73.

Nature or Nurture? MacGregor et al, Arthritis Rheum twins from UK registry Genetic overlap between: Conclusions: The following must be considered in developing a genetic model of LBP: –Psychological variables (e.g., depression) –Past pain experience –Patterns of learning –Cultural factors

Course of LBP Gallagher RM et al Pain 1989, 1995  150 workers disabled by LBP  Medical, radiographic, psychological, motivational and functional testing (5 hour battery)  Independent predictors of poor return to work at 6 months?  Older Age  Less Education  Longer time out of work  External locus of control  unless received workers compensation benefits!  NOT: physical examination findings

Course of LBP Hestbaek L et al. Eur Spine J 2003  Review of studies of course of LBP  After 12 months, the proportion of patients still with LBP averaged 62% across studies (range 42-75%)  LBP more chronic / recurrent than we thought

Course of LBP Burton AK et al Man Ther (UK Study)  Predictors of outcome at 4 years:  Depressive symptoms  Fear-avoidance Weiner D et al, Pain Med 2003  Adults > 70 y/o with LBP (Medicare data)  Predictors of functional disability  Pain severity  Duration of pain

Risk factors for Chronic LBP in VA populations Traumatic spine injury, e.g., –Jumping from moving vehicles –Parachuting –Heavy lifting in hurried conditions Repetitive strain: –Industrial level manual labor in high stress conditions Wartime environment leading to denial of injury, redeployment and repetitive injury High stress and life disruption leading to psychiatric comorbidities

D The derivation of a disabled LBP population D. Pre morbid risk factors: Scoliosis; Combat exposure; Prolonged deployment; Airborne troop; Stiff upper lip; Older; Less education; Psychiatric disorder; Personality Disorder; External locus of control B. Soldiers with onset of injury causing LBP A. DISABLED PAIN POPULATION C. Injured at increased risk for pain disability: 1. Factors increasing risk for disability at injury onset?: TBI; Poor injury mgt; Pain impairments; Anxiety, depression, addiction disorder; Inappropriate back surgery 2. Factors perpetuating pain & disability: Uncontrolled pain; Stoicism; Redeployment; Psychosocial morbidities; Fear- avoidance; Untreated depression / PTSD / SA; Obesity; Poor coping; No rehab; Inflexible workplace. TIME 3. Factors reducing risks for chronicity: Competency/ coping skills; Access to pain medicine/rehab; RTW or vocation; Re-entry crisis Rx; Early depression Rx; Occupational mobility; Education level; Social support; Internal locus of control B C (Adapted from Gallagher et al, Geriatrics 1999; + 6 months

Summary Chronic pain is common Chronic pain has consequences for the individual and society There are many pain diseases Each pain diseases has its own phenomenology Treatment addresses pain generators, mechanisms and biopsychosocial phenomenology