Thursday, November 1, 2012

Misdiagnosis


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A review of the literature published in the Green Journal[1] Table1 lists diagnostic errors by clinical condition from various studies. Striking among them, ruptured abdominal aortic aneurysm was missed 61% and dissecting thoracic aneurysm 35% of the time. The radiologist missed breast cancer on the mammogram 21% of the time. The initial diagnosis of bipolar disorder was wrong 69% of the time. Among patients with fatal pulmonary embolism, the diagnosis was unsuspected 55% of the time. Psoriatic arthritis was missed or wrong 39% of the time. Amazingly, the machine EKG missed atrial fibrillation in 35% of the tracings and the reviewing clinician failed to pick it up in 24% of those.
In my own observation, misdiagnosis is rampant among less threatening clinical conditions especially those offered from outside of the relevant specialty among specialists, as well as the more unusual conditions encountered by primary care physicians. It is not uncommon to misdiagnose various forms of sinus disorder, otitis and respiratory disease. Pneumonia too, while recognized as such often lacks a credible etiology -- due in part to less scrupulous sputum collection and identification by microbiology. With a multitude of causes, pneumonia may be diagnosed by circumstance such as community-acquired pneumonia and treated with a high percentage antibiotic for the so-called community acquired condition.

Trial lawyers claim that the first physician misdiagnoses cancer 45% of the time -- probably not an overstatement.
Medicine is both an art and a science. Some physicians lean so to the side of art that they lay claim to the diagnosis itself. When they “make a diagnosis,” that diagnosis is laid in stone. The treatment, whether appropriate or not, is credited with the success whilst the body cures itself with or in spite of the treatment. So much is the body’s responsiveness to caring, faith and encouragement that the placebo effect is real. Thus, the patient’s response reinforces the physician’s self-confidence and further obscures misdiagnosis.

Then too, there is the right treatment for the wrong diagnosis, often developed over time based on experience, the outcome may be quite effective – or just an accident. Was this how a drug for Parkinson’s came to be effective for influenza, how an anti tuberculosis drug became effective for depression, or how a depression medication came to be effective for pain.
Diagnosis too is like an amoeba; it changes with passing specialties, fashion and even science. Current medical terminology changes as if with the weather, placing a slightly or even a profoundly different slant on the basic concept of pathophysiology and today a new understanding of the basics of disease through advances in molecular biology.

I’ve made the point now so often that is a cliché to add the distortion in diagnostic records produced by insurance clerks. Seeking to submit only the diagnosis that claims processors will accept for reimbursement, the insurance database bears little relationship to the actual doctor’s notes. Furthermore, the ICDMA consistently leagues behind current terminology. Whereas ICDA makes room for acute, sub acute and chronic, it makes little provision for differential diagnosis, presumptive, working or established diagnosis. One can write 3 or 4 digit codes and state the diagnosis simply as chest pain without specific cause or abdominal pain the same way, but in the wisdom of the reimbursement system, a 4 digit code does not garner reimbursement or authorization for further testing. Expediency thus codifies the wrong diagnosis in the accumulated database of medicare, medicaid and other third party claims processing agencies.
A further distortion results from the physician’s reluctance to saddle the patient with a diagnosis, which might cause the patient to lose insurance coverage. The same applies to a prior condition. Sometimes the physician may downplay a frightening diagnosis pending further counseling with the patient. In another case, the physician may avoid the true diagnosis to protect the patient’s confidentiality when a family member or others view or co-pay the insurance claim.
Unfortunately health care planers and even public health base medical policy on this vast corrupted pool of diagnostic data.

Diagnostic errors in hospitals account for 17% of adverse events and 10.5% of adverse events resulted from misdiagnosis.[2] Given that 15% of the time the clinician lists the wrong initial diagnosis, clinical decision support (CDS) – elsewhere called computer decision support system (CDSS) -- makes a lot of sense. While CDS finds its way into most commercial vender based electronic health records (EHR) and internally programed institutional EHRs, very few include diagnostic decision support beyond facilitating the problem list. Wright, Sittig and Ash et al, in the Journal of Informatics (AMIA) list taxonomy of 53 CDS front-end applications taken from a survey of seven selected vendors and four institutions. Only three provide any diagnostic support. Most CDS applications focus on medications, orders, incompatibilities and treatment protocols based on “best evidence.” Obviously, the best treatment protocol applied to a wrong diagnosis does more harm than good. If the clinician lists all of the possibilities as in a differential diagnosis, the list will likely contain the right diagnosis. It then becomes a process of selection and elimination. The final answer may still be in dispute at autopsy but there will be fewer misstatements along the way and a far more credible database. CDS can provide a differential diagnosis along with statical probabilities based on the patient data available. If the CDS contains the criteria for diagnosis and the patient meats that criteria, then the clinician will likely be on the right track. The human mind under the best of circumstances struggles with both memory and statistics. In no way can a computer replace the judgment, the intuition, and the wisdom of a well-educated and experienced physician, but well written database applications can remember it all unerringly, and apply statistical interpretation. Furthermore, to an even higher level of accuracy, the relational database can internally improve its statistical interpretation based on later proven diagnosis and or outcome. Ongoing analysis of internal data amounts to a simple artificial intelligence, but not of the human variety. Therefore, CDS acts as a complement to clinical thinking, not a replacement and an ongoing source of continuing medical education. (CME)

Diagnosis is like an onion, it has many layers. Changing patterns of cause and effect, a long and complex history and the patient’s adaptations both emotionally and physically yield hidden layers. The problem list helps as in problem oriented charting. Still not universally used, it at least provides a list of the elements. Sir Wm. Osler, professor of medicine at the U of Pennsylvania, 1884, Johns Hopkins, 1888, Oxford 1905[3] and the acknowledged father of modern internal medicine, suggested that the physician, in dealing with multiple problems not subscribe multiple diagnoses but rather look for an underlying cause. He also suggested that the physician’s primary role was convincing patients to take fewer medicines; hardly in keeping with today’s `Medicine Wagon` cornucopia of expensive drugs.
Most planners and non-clinicians miss the degree to which diagnosis, treatment and medical knowledge change over time, like an amoeba moving this way and that sometimes rapidly and other times slowly. The changes come with new knowledge, with current fashion and with genomic reinterpretation of the pathophysiology itself.  Furthermore, patients vary greatly as individuals. Geographical regions, even small ones, experience significantly different epidemiological and environmental problems.

Aggregating all of the known diagnoses and syndromes in the World into one database with criteria presents a formidable task. It would have not have been attempted just a few years ago due to limitations in storage capacity. That limitation no longer exists. Accumulating such an open source universal database for diagnostic CDS may go a long way in improving diagnostic accuracy. However, health care institutions and vendors may avoid incorporating a resource sensitive volume of material into their database system.
There are many reasons for the problem of diagnostic inaccuracy.  As mentioned one is the changing criteria and understanding of the etiology of disease with advances in genomics proteinomics and micro-molecular biology. Other problems result from the insurance clerk’s attempt to list a diagnosis compatible with the requirements for testing and or reimbursement. Another results from the snap diagnosis associated with high throughput, efficiencies insisted upon by profit-motivated management. There must be some significant reasons for the dismal ranking of US medicine compared with the rest of the world. Not to beat a dead horse, but a ranking of 36th in infant mortality implies something more than mal distribution of providers and over-treatment. I submit that diagnostic CDS will go a long way towards closing the gap.
Table 1Diagnostic Error Rates from the literature[4]

Tuberculosis / Autopsy                                       50%
Pulmonary Embolism                                           55%
Aortic Aneurism                                                   61%       
Sub Arachnoid Hemorrhage                              30%
Breast Cancer / Mammogram                            21%
Bipolar Disorder                                                   69%
Appendicitis                                                          18%
Cancer Path                  2-9% GYN;   5-12% non-GYN     
Endometriosis                                                       18%
Psoriatic Arthritis / Standard Patient                39%
Atrial Fibrillation / EKG Machine                       35%
Infant Botulism                                                     50%
Diabetes Mellitus                                                 18%
Chest XR by / ER                                                   18%

                               

 



[1] The American Journal of Medicine, vol 121 (5A), May 2008
 
1 Over Confidence as a Cause of Diagnostic Error in Medicine, E.S. Berner & Mark L Graber, m.d. American Journal of Medicine, 2008, Vol 121 S2—S23

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