Medical Provider’s Perspective on Determining Causation

Jaishri Ramesh, M. D.Board Certified Internal Medicine

Industrial Injury Breakdown

• About 75% of industrial injuries are straight forward- they want to get better

• About 20% are in between, will get better with more attention

• Remaining 5% fall in the suspicious category

Burden of Proof

• Injured worker has the burden to prove that an injury or condition arose out of employment.

• If the ER is asserting that the injury was deliberately self inflicted, then the ER has the burden to prove this point by a preponderance of evidence.

Reasonable Medical Probability

• Probability simply means more likely than not

• Physician is called upon to simply state if the injury was “more likely than not” or “at least a 51% likelihood” that the work incident or exposure caused the injury or disability.

Medical Provider’s Role in Worker’s Compensation

• Workers Compensation is a medically driven system

• Medical information is used to guide key decision points, including entry into the system, legal issues of compensability, etc.

Medical Provider’s Role

• Defining injury• Detailed history• Determining causation• Mechanism of injury• Physical examination• Treatment plan• Assessment of work status

Determining Causality in Workers’ Compensation

• Alleged relationship between the diagnosis and the work-related exposure.

• Estimate of the risk of developing the diagnosis from the actual work exposure

• If the relationship has a greater than 50% probability then it is medically probable.

Causation Assessment

1) Record an occupational medical history including detailed description of incident and complete job description.

2) Take a complete medical history, including non-occupational activities.

3) Establish a different diagnosis for patient.

4) Assess the medical probability of the relationship between the assumed diagnosis and the work-related exposure.

Risk Assessment Method

To assess causality you must apply traditional risk assessment techniques developed by Bradford-Hill.

1) Strength of the association2) Consistency of the evidence3) Specificity of the result4) Temporal Relationship5) Biological gradient6) Coherence

Workers’ Compensation Statutes

• Work related exposure must be the “proximate cause” of the disease or injury.

• Proximate cause is defined in Black’s Law Dictionary as the last act “contributory to an injury, without which such injury would not have resulted. The dominant, moving, or producing cause.”

Pre-Existing Medical Condition

• A pre-existing medical condition which may pre-dispose the worker to an injury does not necessarily mean the case is not work-related, the injury is most likely also work-related.

• Case example – Patient with a partial meniscus tea is hit in the leg with heavy equipment and falls, suffering a full thickness meniscus tear.

• Physicians should discuss the impact of pre-existing disease or injury on the current work related condition.

Using Risk AssessmentUsing Risk Assessment

Case example – A worker is exposed to levels of formaldehyde below the OSHA permitted limits

1) The worker claims to have irritant-induced reactive airway disease2) The worker claims the formaldehyde aggravated his pre-existing

asthma.

How would you prove or disprove these assertions?

Always answer this question: “Without the work-relatedexposure or accident, is it medically probable that the patient would have the current diagnosis and requiretreatment?”

Activities of Daily LivingActivities of Daily Living

Generally, if a worker is performing an activity he would normally be expected to perform in day-to-day tasks at home the injury will not be work-related.

Case – An executive suffers a heart attack while reviewing his routine, office

email.

Isolated Mental Impairment

Pursuant to C.R. S. 8-41-301(2)(a), mental impairment:

“…means a recognized, permanent disability arising from an accidental injury arising out of and in the course of employment when the accidental injury involves no physical injury and consists of a psychologically traumatic event that is generally outside of a workers’ usual experience and would evoke significant symptoms of distress in a worker in similar circumstances. A mental impairment shall not be considered to arise out of and in the course of employment if is results from a disciplinary action, work evaluation, job transfer, layoff, demotion, promotion, termination, retirement, or similar action taken in good faith by the employer.”

Remember the final determination of work-relatedness rests with the judicial system. This allows the consideration of course and scope of duties, enforced safety standards, and location of injury.

Steps in Causality Determination

1. Establish diagnosis (or differential diagnosis if further testing required)2. Define Injury or Exposure

Exposure include: Length of exposure Level of exposure Comparison of workers’ exposure to that of the normal population

3. Discuss Intervening Factors4. Explain any scientific evidence supporting a cause and effect relationship between the diagnosis and the exposure or injury5. Assign a medical probability level to the case in question

Medically probable > 50% likely Medically possible < 50% likely

Analyzing Causation

Three Basic Questions:

Does? Can? Did?

CA Workers’ Compensation

• AOE (Arising out of Employment):Conveys the idea of a causal relationship between the employment and the workers’ disability. A worker has the burden of proving the cause and origin of the injury flows from his/her work activities.

• COE (Course of the Employment):Phrase “COE” refers to the time and place where the injury occurred. A worker must prove the time, place, and circumstances of the injury, relate the injury to his or her work or duties and activities incidental to his/her work.

Red Flags

1. Delayed Reporting2. Sketchy Details3. No Witnesses4. Discrepancy in Story5. Monday Morning Claims6. Disgruntled Employee

More Red Flags

1. Old injuries2. Pregnancy3. Whole body pain4. Financial Hardship at Home5. Misses Medical Appointments6. Does not follow Treatment Plan

Physician Must Define Injury

• Did the injury Arise Out of Employment? • Did the injury occur in the Course Of Employment?• Is it More Likely Than Not (at least 51% likelihood). • Is the injury Reasonable (even if not absolutely certain)

Case #1

• Hx: 50 year old male VP at a biotech company. He came in with CC of a chipped tooth-first upper left incisor.

• Mechanism of injury- he was chewing a pencil while he was sitting and talking to security personnel at work.

• Past Medical history was significant for similar problems in the past. His dentist told him he has brittle teeth.

• He thought it was related to work because he was at work when the injury happened.

Causation – Work Related?

• Is this injury related to work?

• Does it fulfill the “arising out of employment” criteria?

Determination of Causation

• What pathological conditions or disability are present?

• What relevant work exposures were present?• What other causes might produce the disease?

(Non-industrial? Pre-existing factors? )• Simple or Complex• Direct cause• Contributing cause• Flare up of old injury• Exacerbation • Aggravation

Is the Injury Old or New ?

• Flare up - worsening of symptoms of an Old Injury. There is no new event.

• Exacerbation - temporary worsening of symptoms of Pre-existing condition (eg. arthritis)- Considered New Injury

• Aggravation - permanent worsening of pre-existing condition - Considered New Injury

Case #2

• 25 yr female with history of a plastic tubing falling on her right forearm at 9 am this morning.

• She has right forearm pain and her whole arm and forearm is swollen and painful.

• PM Hx is significant for RSI of her right shoulder/neck and upper extremity one year ago.

• She was seen at the same clinic for many months. Declared permanent and stationary with permanent restrictions and future medical treatment by a QME.

Case #2 Examination & Treatment

• Exam showed diffuse swelling/tenderness present all over the right hand, forearm, and arm. No localized bruise or swelling over contused area of Rt. forearm.

• Assessment: Mild contusion Rt. Forearm.• Diffuse swelling is pre-existing, from prior

injury, unresolved.• X ray, ice/ OTC MEDS, Regular work.• Observation/Reassurance

Important Details of Injury

• What is the actual Date of injury?• What is the Time of injury?• Was Exposure at work?• Is there Physical or Psychological

Trauma that is measurable by objective findings?

• Are there an Unbroken Chain of Events?

Case #3 Don’t ask, Don’t tell

• 40 year old male working in the car assembly plant for 8 years in paint shop. He worked in the paint booth and his work involved use of a spray gun connected to heavy tubes, and repetitive bending and twisting all day. EE reported low back pain to his supervisor at 8.30 am and was sent to the onsite clinic right away.

• The nurse triaged him and thought that his injury was pretty bad and she consulted with me to authorize rest of the shift off.

Case #3Exam & History

Q- When did the back pain start?A- This morning.Q.- What time?A.- Very early.Q.- Did you have any pain before coming to work

today?A. Yes, I had a bad back pain when I got up this

morning.Q.- Why do you think that this is related to work?A.- I did not say it was related to work.

Connect the Dots

• Never assume causation• Ask relevant questions • Make sure that exposure at work

and the concerned injury have a cause and effect relationship.

Case # 4

• AB is a 24 yr old male construction worker. About 2 weeks prior to coming in he had a 2 x 6 ft. piece of lumber fall on right foot. He was wearing work boots. He had minimal discomfort. He denies excessive pain and was able to work normally. On the day of clinic visit, he woke up with severe pain in the right foot with inability to bear weight – thus he thought it was from injury and was brought in by supervisor. On exam, he had a warm red swollen big toe area with exquisite tenderness over the 1st metatarsophalangeal (MTP) joint. Any ROMs of MTP were extremely painful. He was having inability to bear weight on his forefoot. X-ray of the right foot and big toe were normal.

• Diagnosis: “Gout”. • Causation: Non-industrial. It was unrelated to industrial exposure of

lumber striking his foot. Patient was referred to PCP

Case # 5

• CD is a 34 yr old Middle Eastern male who had worked for a SW company for 3 yrs as a SW engineer. He worked at a desk doing computer work 6-8 hrs/day. He presented with a history of LB pain that persisted. He thought it was due to prolonged sitting at work. He went to his PCP who examined him and told him he had “LBP” due to prolonged sitting. He was advised to exercise and change position at work. The pain was a little better when not sitting for long periods and with exercising/activity. Since it persisted he went to an Orthopedic Surgeon who ordered x-rays and advised him to f/u after x-rays. Meanwhile he reported to employer who referred him to me. On exam he had mild tenderness over lower L spine and SI joint area ROMs were 90% in all directions. All tests for lumbar Radiculopathy were negative. Something did not fit, didn’t make sense.

Case # 5 Continued

• I called his Orthopedic Surgeon’s office and obtained medical records. X-ray report showed “Bilateral Sacro Iliitis” and the differential diagnosis was Ankylosing Spondylitis (AS). AS is a familial long term spinal disease that causes inflammation of the spine causing “bamboo spine” and S1 joints.

• Thus it was determined to be “non-industrial” and he was referred to his PCP.

Case # 6

• EF is a meat cutter who worked at a grocery store who came in for left eye symptoms. He was cutting meat with saw and felt some “bone dust” go into his eye 2 days prior. He wiped his face off and washed his left eye and felt ok. He continued working that day and the next day. The following day he woke up with redness and swelling of left upper eyelid with stinging pain. He though it was related to the bone dust getting into his eye and was referred by his employer to our clinic. On exam, his left upper eyelid was swollen, red and inflamed. The eye was ok with no foreign body, abrasion, etc. The cornea and conjunctiva were ok.

• Diagnosis: “Blepharitis” a non-industrial condition.

Case # 7

• GH is an overweight 54 year old male who presented with the history of “my belly button popped out and is painful.” He stated that he was a “supervisor” who was walking in the hallway at work and noted sharp pain in the “belly button area.” He denied lifting heavy objects or any exertional activity. He did not do any heavy work – “just supervised his boys”. On exam, he is 5’10” tall weighing 238 lbs. Abdominal exam revealed a very large protuberant abdomen. There was a 1” umbilical hernia which was soft.

• The umbilical hernia was deemed non-industrial.

Case # 8

• Ms. IJ is a 36 yr. old software engineer who did computer work for 6-8 hrs/day who presented with “burning right shoulder pain” for 2 weeks. She denied wrist FA or elbow pain or paresthesis. She thought that the computer work done on a daily basis at work caused her shoulder pain. She was taking OTC Advil with no relief of symptoms. She denied any other past medical history. She denied previous work comp claims. She denied any other non-industrial causes. She denied hobbies, sports, and other off work activities. On exam, her right wrist hand FA elbow exam was all “normal.” Right shoulder exam showed marked tenderness over anterior humerus. ROMs of the shoulder – abduction and internal rotation was very limited. Impingement tests were positive. X-ray of the right shoulder was obtained which showed chunks of calcific deposits adjacent to the humerus.

• Diagnosis: Calcific Tendinitis. Causation: Non-industrial, referred to PCP

Case # 9

• Ms. KL is a 48 yr old school teacher who was on yard duty during lunch time and noticed mild irritation in left eye. She didn’t report anything getting into her eye, trauma or anything else. She said it “might have been dusty in the yard with children playing.” She reported to her Principal who said her eye was very red thus referred to our clinic. On exam left eye had no FB, no swelling of upper or lower eyelid. There was sub conjuctival hemorrhage in her eye with no infection. On further questioning she mentioned a history of HTN and has been stable on meds.

• Diagnosis: Spontaneous sub conjunctival hemorrhage. • Causation: Non-industrial, referred to PCP

Case # 10

• Mr. MN is a 34 yr old laborer who was exposed to concrete dust at work for 2 days as they were grinding concrete. He was wearing a mask. He developed the onset of nasal congestion, sinus congestion, severe frontal headaches and mild cough. His nasal discharge was initially clear then changed to yellow and greenish thick discharge. On 2 occasions he noted some “blood” when he blew his nose. He was unable to sleep due to symptoms. His employer referred him as a possible exposure to cement dust. On exam, he appeared ill. Temp – 99.8°F, BP – 126/82, HR – 88/min., RR – 8-10 min., Pulse Ox – 99%.

• Exam: Marked tenderness over frontal and maxillary sinuses. Nasal mucus membranes were congested with mucoid discharge. Bending head downward caused a lot of pressure and headache. Ears – Normal TMs., Lungs – CTA, CVS – Normal.

• Diagnosis: Acute Sinusitis• Causation: Non-industrial, referred to PCP

Any Questions?Thank you

Jaishri Ramesh, M. D.Board Certified Internal Medicine