How Doctors Think. Canadian Medical Protective Association. Challenges to diagnosing. Risk Management Services

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1 Canadian Medical Protective Association Risk Management Services How Doctors Think Challenges to diagnosing Susan Swiggum MD, FRCPC, FAAD, Senior Physician Risk Manager Vancouver September 2012 CMPA

2 Case 1: A 23 year old woman from a nearby addictions treatment facility was seen in the Emergency department. She has a past history of paranoid schizophrenia. Her chief complaint was anxiety, chest pain and shortness of breath which had been going on for about one week. An electrocardiogram ordered by the triage nurse and was normal. The nurse urged the emergency physician to discharge the patient back to the addiction center. She informed him that the patient was well known to the department staff and was a frequent flyer. The nurse suggested the patient likely had an URI. Certainly they had seen a number of patients with viral respiratory illnesses in the last few weeks. When the emergency physician went to see the patient he was informed that she had gone for a cigarette. He was very angry and verbally expressed his irritation to the nurse. These patients with self-inflicted problems tie up our busy emergency departments. When the patient returned he admonished her for wasting his time. Cursory examination revealed a few rhales, especially on expiration. Vital signs and oxygen saturation were normal. A chest x-ray ordered to eliminate the possibility of pneumonia was normal. The physician diagnosed asthma and gave her advice to quit smoking. She was discharged with instructions to return if her condition deteriorated or she experienced any pain or respiratory difficulty. The patient returned to the addictions center where she continued to have chest pain, cough and shortness of breath. She was reassured by the staff that her normal cardiogram and her assessment by the emergency physician ruled out any serious problem. Two days later she suffered a cardiac arrest and could not be resuscitated. At autopsy revealed multiple small emboli in both lungs with a bilateral massive pulmonary saddle embolus. What cognitive dispositions to respond can you identify? What system failures contributed to the missed diagnosis?

3 Case 2: A 19 year old, slender built male student was seen by his family physician for acute onset, sharp chest pain and shortness of breath. He had a past history of a pneumothorax. Suspecting a recurrence the family physician sent him to the emergency department. He did not contact the emergency physician nor did he send a note with the patient. The patient explained to the triage nurse that he had had a pneumothorax in the past and has been sent to the emergency for a chest x-ray to rule out a recurrence. As the department was extremely busy the charge nurse ordered the x-ray and asked the emergency physician to quickly assess the patient for a recurrence of a pneumothorax. The physician continues to be busy with many other patients so the charge nurse urges her to review the x-ray so the patient can be treated or released. Finally the physician has an opportunity to review the x-ray and finds no pneumothorax. She briefly sees the patient. Air entry is equal bilaterally, there are no adventitious sounds and the chest pain is reproduced by palpation of the chest wall. The physician reassured the patient that there was no pneumothorax. She discharged the patient on ibuprofen having made a diagnosis of musculoskeletal pain. Later that day the radiologist read the chest x-ray and reported that the lung fields were clear and there was no evidence of a pneumothorax. She also reported that the heart was distinctly enlarged with the appearance of pericarditis. This information was not relayed to the emergency physician. The student continued to have chest pain during the night. The next morning he collapsed while having breakfast. Autopsy revealed a thoracic aortic dissection. What cognitive dispositions to respond can you identify? What system failures contributed to the missed diagnosis?

4 Cognitive dispositions to respond Case 1 Case 2 Over-attachment to a particular diagnosis Failure to consider alternative diagnosis Inheriting someone else s thinking Prevalence, perception or estimation Premature closure: Accepting a diagnosis before it has been verified. Anchoring: Locking into a diagnosis and not adjusting in light of later information. Confirmation bias: Looking for confirmation evidence to support a diagnosis. Search satisfaction: Call off the search when something is found. Sutton s Slip: Go for the money (obvious diagnosis). Unpacking principles: Failure to elicit all the information on history so possibilities are discounted. Diagnostic momentum: Through others a possibility gathers momentum, excluding other possibilities. Bandwagon effect: The tendency to believe things because others do. Ascertainment effect: Thinking shaped by prior experiences or bias. Availability bias: Things are more likely if they readily come to mind. Playing the odds: With ambiguous presentations opt for benign diagnosis than a serious one. Gambler s fallacy: Assuming a sequence of diagnoses will not continue.

5 CMPA Good Practices Guide PAGE 1 OF 4 COMMON COGNITIVE BIASES Use of various strategies may help prevent many of the cognitive biases. Here are some examples of common biases and strategies for dealing with them. 4 ANCHORING Focusing on one particular symptom, sign, or piece of information, or a particular diagnosis early in the diagnostic process and failing to make any adjustments for other possibilities either by discounting or ignoring them. S 1. A 48-year-old woman with known osteoporosis presents with severe back pain after a day of vigorous gardening. A plain X-ray shows a vertebral compression fracture. Her physician attributes the fracture to her osteoporosis. The physician s failure to consider other diagnoses results in a delay in the diagnosis of metastatic carcinoma. The physician anchored on the osteoporosis diagnosis rather than developing a differential diagnosis to explain the fracture. 2. A 22-year-old man presents during flu season with nausea, vomiting, and abdominal pain. The patient does not have diarrhea. The abdomen is soft and mildly tender diffusely without rebound, and with normal bowel sounds. The patient is diagnosed with gastroenteritis as the physician focuses on the vomiting and deemphasizes the abdominal pain and absence of diarrhea. The patient is discharged. Appendicitis is diagnosed two days later. 4Gather sufficient information. 4Develop a differential diagnosis. 4Consider the worst case scenario. Reconsider the diagnosis if: 4there are new symptoms or signs 4the patient without treatment is not following the natural course of the assumed illness and is not improving 4the patient is not improving as expected The Canadian Medical Protective Association 4

6 34 CMPA Good Practices Guide PAGE 2 OF 4 PREMATURE CLOSURE Uncritical acceptance of an initial diagnosis and failing to search for information to challenge the provisional diagnosis or to consider other diagnoses. A patient presents with a sudden, severe headache and vomiting following a banquet. The patient believes this is due to food poisoning. As the neurologic examination is normal, the physician accepts the patient s provisional diagnosis. The patient deteriorates and a leaking cerebral aneurysm is eventually diagnosed. 4Gather sufficient information. 4Develop a differential diagnosis. 4Identify any red flag symptoms and investigate appropriately. Consider the worst case scenario what you don t want to miss. 4Consider consultation with a colleague or specialist. SEARCH SATISFACTION When one abnormality has been found, calling off the search and failing to look for others. A trauma patient is rushed to the OR with a ruptured spleen. Fortunately he survives the surgery; however, he continues to complain of severe lower abdominal pain. Three days post-op a fractured pelvis is diagnosed. This finding had already been discovered on the initial radiological examination following arrival in the emergency department but had been overlooked due to the ruptured spleen. Having identified one abnormality, ask yourself if there is anything more going on? ZEBRA RETREAT If it s uncommon, this isn t it backing away from a rare diagnosis. A 28-year-old woman on the birth control pill presents with calf pain following a slip at work. Her family physician diagnoses a calf muscle strain. The patient dies two days later from a massive pulmonary embolus. Muscular strain following an injury is a more common diagnosis, however, in this case the diagnosis should have been Deep Vein Thrombosis (DVT). Physicians are often taught if you hear hoof beats, think horses not zebras, and generally this is good advice. But, by considering the worst case scenario diagnosis and then ruling it in or out, you will be less likely to misdiagnosis the patient. 34

7 34 CMPA Good Practices Guide PAGE 3 OF 4 BANDWAGON EFFECT (diagnostic momentum) Diagnostic labels may stick to a patient. If everyone else thinks it, it must be right! The nurses in the emergency department ask you to see and quickly discharge Miss Jones. They explain that she is a regular in the department and is seeking narcotics. Tonight Miss Jones presents again with abdominal pain. Fortunately, you perform a thorough history and physical exam and diagnose a ruptured ectopic pregnancy. 4Assess patients appropriately. 4Consciously decide to arrive at your diagnosis or differential diagnosis independent of the labels applied by others. 4A diagnostic time out to reconsider the differential diagnosis may be helpful. ATTRIBUTION ERROR A form of stereotyping: explaining a patient s condition on the basis of their disposition or character rather than seeking a valid medical explanation. An intoxicated homeless man presents with a large ulcer on the plantar surface of his right foot. As he is unclean, unkempt and without shoes, you assume the ulcer is traumatic in origin and there would be little chance of improvement given his lifestyle. Further investigation reveals he is not intoxicated, but rather diabetic. With appropriate therapy and support the patient is able to manage his diabetes as well as heal the foot ulcer. Every patient and every healthcare provider are unique individuals. Unfortunately, we may be biased toward a patient with a particular illness, particularly a psychiatric illness or drug or alcohol addiction. Avoid the rush to stereotype a patient based on his or her culture, gender, illness or disability, religious or sexual orientation, and so on. Acknowledge that you may not have the best rapport with a specific patient and take particular care with the impact of this on your decision making and judgment. 34

8 CMPA Good Practices Guide PAGE 4 OF 4 3 AUTHORITY BIAS Declining to disagree with an expert. The hospital you are working in as a medical student is short of beds. The senior resident sends you to the medical ward to quickly discharge a 67-year-old patient admitted the day before with COPD. You are told the patient has improved and can go home to follow up with the family doctor. When you go to see the patient, the family members take you aside and voice their strong concern about discharging the patient. You decide to re-examine the patient, and find the patient in mild respiratory distress. You repeat the vital signs and the patient now has a temperature of 39 C. Concerned, you telephone the resident, and learn that this is something the family doctor should deal with. What should you do now? All members of a team should have a voice and any team member should speak up respectfully if there is a concern about the safety of a patient. AVAILABILITY HEURISTIC Recent or vivid patient diagnoses are more easily brought to mind (i.e. are more available) and overemphasized in assessing the probability of a current diagnosis. A heuristic is a mental shortcut. S In influenza season, it is tempting to consider all patients with fever and myalgias as having influenza. Similarly, you may see every slightly irregular light brown nevus as a potential melanoma after you were surprised by an unexpected diagnosis of melanoma in a recent biopsy. This can lead to inappropriate biopsies of clinically benign lesions. 4Be aware of the influence of recent diagnoses on your diagnostic acumen. On the one hand, watch for red flags or symptoms or signs inconsistent with a common, less serious diagnosis. On the other hand, don t over-investigate or over-treat based on an unexpected recent diagnosis in another patient. 3 P.O. Box 8225, Station T, Ottawa ON K1G 3H7 T , cmpa-acpm.ca C.P. 8225, Succursale T, Ottawa ON K1G 3H7 Tél : , cmpa-acpm.ca

9 4 CMPA Good Practices Guide PAGE 1 OF 2 DIAGNOSTIC TIPS FROM THE CMPA S EXPERIENCE The following tips collected from CMPA's medico-legal case files will help you avoid common problems related to the diagnostic process. HISTORY TAKING AND DATA COLLECTION In a legal action, peer experts will be critical if insufficient information had been obtained from the patient. 4Have you taken an adequate history of the patient s health condition and provided the patient with the opportunity to express his or her current health concerns? 4If the patient is unable to provide a history (e.g. language barrier, capacity issue, etc.), have you consulted those who may be able to assist in obtaining the history? 4Have you adequately assessed any relevant risk factors, including family history, which might help in diagnosis? 4Are there any red flag symptoms? 4Have you determined what the patient has already done to manage his or her symptoms? 4If assessing a patient over the telephone, have you obtained sufficient history to be able to provide a professional opinion? 4Have you read the notes taken by other healthcare professionals (e.g. nurses, paramedics)? 4Are pertinent medical records, test results, and consultation reports available and have they been reviewed? PHYSICAL EXAMINATION In a legal action, peer experts will be critical if they consider the physical examination to have been cursory given the patient s symptoms. 4Have you performed an appropriate physical examination? 4Is it necessary to take the vital signs, and have you accounted for any abnormalities? 4Have you assessed the patient appropriately for the clinical complaint (e.g. to examine the abdomen of a patient with new onset abdominal pain, the patient is undressed and gowned, lying prone)? To avoid misunderstanding, explain the reasons for the physical examination, particularly of the genitalia. Consider having a chaperone present for intimate examinations. DIFFERENTIAL DIAGNOSIS Developing a list of possible conditions that might produce a patient s symptoms and signs is an important part of clinical reasoning. 4If a serious diagnosis comes to mind based on a patient s symptoms, have you considered the likelihood of it and whether it needs to be ruled out by testing or referral? 4Because many serious disorders are challenging to diagnose, have you considered ruling out the worst case scenario? 4As a medical student, have you discussed possible diagnoses with your supervisor? (Many supervisors prefer discussing a differential diagnosis prior to having it entered in the medical record by the student.) The Canadian Medical Protective Association 4

10 CMPA Good Practices Guide PAGE 2 OF 2 3 FORMULATING A DIAGNOSIS Relying solely on the classic features of a disease may be misleading. That s because the clinical presentation of a disease often varies: the symptoms and signs of many conditions are non-specific initially and may require hours, days, or even months to develop. 4Do you have sufficient understanding of the clinical presentation to offer an opinion on the diagnosis? 4What other diagnosis could it be? How might the treatment to date have altered the clinical pattern? (When assuming the transfer of care of a patient, reformulating the differential diagnosis may be prudent, especially if the clinical picture is evolving, the diagnosis is not yet firmly established, or the clinical care to date has not resolved the concern.) 4If the patient returns with persistent symptoms or fails to respond to the therapy as expected, have you considered starting over with a new evaluation and look at alternative diagnoses? 4Have you considered using diagnostic decision support tools (sometimes part of electronic health record systems)? 4Are you distressed by the patient s condition or behaviour? (Allowing yourself to become anxious by a particular case may cloud your judgment and inhibit an accurate diagnosis.) ORDERING INVESTIGATIONS When deciding whether to use an available albeit limited healthcare resource, use sound medical judgment and act in your patient s best interests. 4Are laboratory tests, biopsy, diagnostic imaging, or other investigations indicated? 4Are you familiar with the current clinical practice guidelines for the investigation of a suspected condition? 4Have you requested the appropriate investigation? Is the test available in a timely manner? If not, have you considered alternatives and discussed this with the patient? 4Does your completed diagnostic imaging requisition contain pertinent clinical information to help the radiologist? 4Does your completed requisition contain the pertinent clinical and specimen information as well as the correct patient identifiers? 4Is it possible the patient is pregnant? If it is a possibility, has it been ruled out with an appropriately timed pregnancy test? Is the investigation contraindicated in pregnancy? Has the patient been informed of the risks and benefits of the proposed investigation or treatment for herself and the fetus? 3 P.O. Box 8225, Station T, Ottawa ON K1G 3H7 T , cmpa-acpm.ca C.P. 8225, Succursale T, Ottawa ON K1G 3H7 Tél : , cmpa-acpm.ca