Clinical Diagnosis as a Dynamic Cognitive Process: Application of Bloom's Taxonomy for Educational Objectives in the Cognitive Domain*
Kanu E.O. Nkanginieme, MD, FmCPaed., University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria
Making a diagnosis is the pivotal cognitive activity of every practicing doctor. A correct diagnosis will in most cases lead to appropriate treatment. With the high cost of health care, increased patient awareness, medico-legal and insurance pressures, every doctor must be empathic, accountable and cost-effective in patient care. Diagnosis must therefore always be logical and defensible based on a consideration of the dynamic internal and external environment of a living human. Investigations and treatment must be justifiable on the basis of the patients situational reality rather than to compensate for the doctor's deficiencies. Self audit is a vital pre-requisite for accountability of actions or thoughts. This is consistent with the identification of four key factors of clinical decision making that reflect current trends in medicine: quality, cost, ethics and legal concerns (1).
To the experienced diagnostician, the thought processes involved in formulating a diagnosis is largely subconscious. When asked, most would attribute that capacity to knowledge and experience accumulated over years of practice. In day-to-day life and at the bedside, teachers and learners take the thought process for granted. Some will, at best, look at learning from the point of view of either memorizing or understanding. Although the thought process has been recognized as complex, there was no uniformly accepted way of describing the complexity until Benjamin Bloom et. al (2) succeeded in classifying the thought process into six very dynamic levels. These levels increase in complexity, from knowledge as the baseline level, through comprehension, application, analysis, synthesis, to evaluation as the highest level. This classification is referred to as the "Cognitive Domain of Bloom's Taxonomy of Educational Objectives". There are other domains, "Affective" and "Psycho-motor", that address the emotional feelings associated with though process and the correctness of skill performance, respectively, but for our immediate purpose we shall focus on only the cognitive domain. Table1 outlines each level of cognition along with operative words illustrating the type of thought activity the level describes.
Early studies of cognition in problem-solving were based on a concept of process over content3. Over the years, clinical reasoning / diagnosis has tended to be looked upon as a categorization task. Cognition in clinical diagnosis, consequently, has been approached from fixed points of view, such as "frameworks of clinical situation" or "expert and novice diagnosticians". Others have looked at the sequence of utilization of clinical material, as "forward and backward reasoning(4,5,6,7,8,9). These efforts at 'analysis of the thought process' (meta-cognition) of clinical diagnosis have apparently utilized isolated aspects of the Bloom's taxonomy without the benefit of the dynamism of that classification. The very dynamic nature of the cognitive process in clinical diagnosis in a live patient may be one of the special characteristics of both medical knowledge and the diagnostic task which can explain some departures of clinical reasoning from cognition in non-medical domains(10). It is possible that the original concept of "process over content" holds true for cognition in the clinical setting. As a clinician and neophyte student of cognition, I have come to appreciate the extreme dynamism of the thought process involved in diagnosis and the possible futility of trying to analyze its content in a fixed framework or model. In the teaching context, an astute diagnostician should be able to externalize the thought process involved in making a diagnosis for independent study and analysis by students and peers. It is probably the prevailing difficulty in routinely doing this that has tended to mystify "the art of diagnosis" and perpetuated the notions of 'hunches' and 'impressions' in clinical practice at the expense of students' learning. As dynamic and interrelated as its different levels are, it seems to me that there has been no deliberate effort to systematically apply Bloom's classification of the cognitive domain to meta-cognition of the diagnostic process, irrespective of level of expertise. This is therefore a modest effort to re-introduce this classic classification scheme to medical practitioners, educators and students. The ultimate aim is that clinicians, teachers as well as students should:
1. Understand the cognitive domain of Bloom's taxonomy of educational
A typical clinical summary will be used to introduce and illustrate the application of Bloom's Taxonomy of the Cognitive Domain of Educational objectives in clinical diagnosis. This approach unavoidably has the limitation of assuming that the reader is proficient in obtaining clinical information and putting it in a clear, concise and complete summary format, and that the reader has a functional knowledge of pathogenesis, pathophysiology and epidemiology of common disease conditions. The aspects of the sample case will be related to the appropriate levels of Bloom's taxonomy in Table 2. It is recommended that the reader should not refer to this table without a prior personal attempt to analyze the diagnostic process, using the illustrations of the levels of the taxonomy.
Sample Case Summary:
While visiting her African friends, a retired physician was presented with a seven year old boy who has complaints of cough, anorexia, weakness and tiredness. He had fever and swollen painful joints three weeks previously. Signs she elicited included pyrexia, pallor, pedal edema, axillary nodes, rapid pulse, active precordium, palpable thrill and tender hepatomegaly. There was no stethoscope to auscultate the chest. She immediately referred the boy to a pediatrician in a nearby children's hospital where she had been a teacher for over twenty years.
Our experienced physician made a clear functional diagnosis of heart failure probably due to valvular damage from rheumatic fever (speculative pathological and etiologic diagnoses). She advised that they exclude leukemia, septicemia, rheumatoid arthritis and sickle cell disease , regretted her inability to start the child on frusemide prior to referral, and warned about the possibility of endocarditis. At the hospital the young pediatrician quickly verified the history and physical findings, auscultated the chest, prescribed frusemide and then ordered some laboratory and radiological investigations. He gave the referral letter to his resident saying, "Study this closely. It always amazes me how my old teacher arrives at the correct diagnosis with minimal tests. These investigations would be largely for our further education and for insurance".
Illustration of Levels of Cognition in Clinical Diagnosis
To be able to make such an impeccable clinical diagnosis one must be able to ; 1) obtain and appreciate the meaning of symptoms and signs of the patient, 2) identify the appropriate organ system/s involved in disease, 3) speculatively identify the possible pathological processes that is/are occurring, 4) know how to differentiate one pathological process from the other, 5) know from epidemiology the most likely causes of particular pathological processes, and 6) evaluate all pieces of information available and decide on the likely cause and course of illness.
In other words, one should; 1) have acquired good working knowledge of the relevant structures and their function, 2)be able to comprehend the meaning of that knowledge, 3) know when and how to apply the knowledge, 4) be able to analyze the relationships of different pieces of information, 5) be able to synthesize pieces of information and their relationships into a meaningful whole and 6) cross check the processing of the entire information to evaluate whether their are defensible.
There is ordinarily a sequential progression from knowledge to comprehension, to application, to analysis, to synthesis and finally evaluation. If you do not have the knowledge, there will be nothing to comprehend. If you acquire knowledge but are unable to comprehend the meaning, you cannot apply it reasonably. Thus the stratification of cognition into levels that are interrelated and interdependent in a very dynamic way.
Looking at the six levels and the key words in Table1 , it should be obvious that all levels of cognition are involved in clinical thought and performance, from history taking, physical examination, diagnosis, differential diagnosis, choice of tests, treatment and prognosis. In clinical diagnosis, knowledge, comprehension and, in most cases, application are taken for granted. That is why, for example, at the outset it was stated that to use the sample clinical summary it is assumed that the reader is proficient in obtaining clinical information and relating this to pathogenesis and pathophysiology. Prior to that, knowledge of anatomy, physiology and biochemistry must have been acquired to comprehend the normal structure and function of the human body. Learning to perform the physical examination of a normal individual will enable one to recognize normality and chose normal from abnormal, but may not enable one to distinguish one abnormal condition from another. Knowledge of the physical findings in two abnormal conditions is needed to be able to distinguish between them. Thus one is required to acquire knowledge of the physical findings in diverse clinical conditions.
Usually a condition affecting one body system can produce structural or functional abnormality in different parts of the body. One therefore needs to acquire knowledge of the pathological changes and the clinical manifestations of various diseases in particular systems. This will enable one to translate the symptoms and signs to a particular system and from their character one may begin to associate them to particular types of pathological processes. With knowledge of the features of different pathological processes one may distinguish a particular process from others, and coupled to one's knowledge of epidemiology of diseases one may begin to formulate a diagnosis. So, at every point in the processing of information one moves from one level to the other in increasing order of complexity, at times going back and forward. Without appropriate knowledge, it is difficult to proceed logically to the next level of cognition. A lower level can always be used to facilitate a higher level of cognition. See Table2.
In most learning situations there are "novices" and "experts" as well as the spectrum in-between. The critical differences between the expert and novice, given the same innate ability, is knowledge base, the operational level of cognition and the transition time from one level of cognition to the other. For example, given the same knowledge base, the person with a faster comprehension time is likely to apply the knowledge earlier. Again comprehension time may be positively or negatively influenced by diverse and unrelated knowledge. Whereas a student spends time trying to recognize and comprehend discrete pieces of information, an resident who had previously applied the various pieces of information will already be analyzing or synthesizing them, observation of features and recognition of relationships being essentially instantaneous (with nearly "zero" comprehension and application times) and therefore almost sub-conscious. This particular process is what is often referred to as the "hunch" of the physician as the patient walks into the consulting room. It and the fact that the diagnostic process also automatically embodies considerations for the promotion, maintenance and restoration of the health of a living being are probably some of the characteristics that contribute to the departure of medical diagnostic cognition from cognition in non-medical domains. Thus, at times information processing that appears to operate at the analysis or synthesis levels for a student may seem to operate at the knowledge level for a resident. Using "palpable thrill" in the sample case as an example, the student may still have problems identifying a thrill or associating it with a given system, whereas a resident immediately recognizes it as indicative of an organic valvular heart lesion.
My untested hypothesis therefore is that the expert usually has more time to operate at the level of evaluation because of shortened comprehension, application and analysis times. This is consistent with the observations of different knowledge levels of novices, interns and experts(11,12,13,) and the observed superiority of experts over novices and interns in diagnostic accuracy with the shortest exposure to clinical information(14).
Of the several influences that impinge on the diagnostic cognitive process, perhaps the most crucial is the issue of life and death. Thus the process (even in the same physician), whether novice or expert is different for different conditions depending on the degree of threat to life and recognition of that threat. Of the various non-medical cognitive domains, perhaps that of priests and commercial airline pilots are closest to physicians in this respect. It may be illuminating to explore the cognitive processes in these professions that are at times referred to as "noble". The influence of the affective domain on the cognitive process may also be more potent in these situations.
In the traditional pre-clinical years cognition by students is mostly at the knowledge and comprehension levels. In the first clinical year it moves to the application and analysis levels with expansion of the knowledge base and reduction of comprehension time. By the final year, students should be functioning mostly at the analysis and synthesis levels with occasional evaluation level processing to effectively solve the clinical problems that they are likely to encounter. However they are not aware of this process because metacognition is not part of their training at any level. The greater comfort and sophistication, in the clinical setting, of the final year student compared to the junior students is probably a manifestation of the good feeling associated with improved cognitive processing of clinical information. This can be further enhanced if the awareness of improvement is based on objective self evaluation.
Universal appreciation and application of the dynamics of the levels of cognition by all players in medical practice and education should make meta-cognition of the diagnostic process possible. Even the most "unconscious thoughts" can be brought to consciousness and thus made "teachable". The rapid processing of rapidly observed phenomenon which hitherto had been regarded as "hunches" or "impressions" can be subjected to a systematic slow "play back", using this classification scheme of the cognitive domain. The diagnostic process thus becomes subject to a systematic evaluation.
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Dr. Nkanginieme is a Senior Lecturer/Consultant in Pediatrics and Child Health at the University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. He was a Visiting Fellow in Medical Education (IMSP) at The University of Texas Medical Branch, Galveston, Texas while this paper was developed.
Nkanginieme K.EO. Clinical diagnosis as a dynamic cognitive process: Application of Bloom's taxonomy for educational objectives in the cognitive domain. Med Educ Online [serial online] 1997;2:1. Available from: URL http://www.Med-Ed-Online.