Diagnostic decisions are not easy but very crucial. The diagnosis is a vital part in patient care as it not only affects the patient but the society at large. Diagnostic errors appear to be the most common, most costly and most dangerous of medical mistakes. The outpatient diagnostic errors are as high as 5.08% and half of this could be potentially harmful.
The diagnosis is finally done by the caregiver and diagnostic label will guide the expensive investigations and management of the patient. The rapid escalation in the cost of medical care and a large number of patients still being treated in resource deprived settings makes it essential for the caregiver to utilize history and clinical examination as the most important tool in the diagnostic process. The statistical parameters of objectivity employed in lab parameters and therapeutics if applied to history taking and clinical examination will yield more value cost effectively which is called the practice of evidence based clinical examination.
This practice needs effort from the caregiver. The article tries to explore this decision making process to make it more effective in the diagnosis. The technical definition of heuristics is a simple procedure that helps find adequate though often imperfect, but rapid answers to difficult questions. The technical definition of rational is consistent with or based on reason or logic. An unbiased appreciation of uncertainty is the cornerstone of rationality. The article is an attempt to look at the diagnostic decision making.
The decision making in medical disorders was analyzed to see the working of human mind from Evidence Based Medicine resources such as cochrane library, British medical journal updates and Journal of American medical association.
The decision making is an important aspect in the field of medicine. The diagnostic process involves the synthesis of data available from the patient and the evidence regarding the disease in medical literature. This synthesis determines the diagnosis and management of the patient.
The human mind works as 2 selves namely system 1 and system 2.
Heuristics is system 1.
The characteristics of system 1 are:
1. Generates impressions and feelings,
2. Can be programmed by system 2 to mobilize attention when a particular pattern
3. Operates immediately,
4. Executes skilled responses and generates
skilled intuitions when trained adequately,
5. Distinguishes surprise from normal,
6. Focuses on existing evidence-what you
see is all there is(WYSIATI),
7. Represents sets by norms and prototype, 8. Computes more than intended (shot gun approach),
9. Frames decision problems narrowly, in isolation from one another and
10. Over weights low probabilities.
The review of diagnosis decision making revealed that system 1 is activated for emergencies where time is the crucial factor. This is the basic premise for protocols which are operational in casualties and emergency wards of well managed hospitals. This has created the need for intensive care unit protocol books.
The same heuristic based approach has driven the Basic Life Support/Advanced Cardiac Life Support algorithms which are time bound. The ACLS/BLS guidelines are based on expert opinion, retrospective studies and animal research because no Randomized Controlled Trials can be done for resuscitative research and reflects heuristic thinking. The heuristic thinking has also reduced the mortality in medical emergencies like acute myocardial infarction, stroke and anaphylaxis where guidelines are formed by a combination of evidence and heuristic thinking by professional bodies.
The efficacy of system 1 is also reflected in the recent emergence of emergency medicine as a distinct course in the curricula of medical teaching.
The application of heuristics is also reflected in dedicated emergency and intensive care unit teams which manage only emergencies in organized health care settings.
The system 1 is prone for following type of heuristic errors namely 1) Representation, 2) Availability, 3) Association, 4) Illusion of validity and 5) Framing effect.
The system 2 has to operate overcoming the biases of system 1. The system 2 controls and guides system 1 when activated and reduces the errors. The system 2 operates more elaborately collecting all the facts pertaining to the situation. The system 2 also generates questions and operates leisurely. There is scope for rethinking, revising and contemplation.
The bias or weakness of system 1 is as follows:
1. Association heuristics; Statistics gives objectivity to opinions because it considers what is known as chance occurrence. Events happen randomly. There is no causative factor for events and there need not be a coherent pattern for the occurrence. Statistics trumps causes. System 2 needs to tame the intuitions. The information supporting the hypothesis should be given more validity rather than the coherence of the concept.
2. Availability heuristics; the process of judgment based on the ease which instances come to the mind. This process is a big contributor for bias and was defined by Norbert Schwarz. Baseline predictions based on medical statistics to be relied upon rather than uniqueness of cases.
3. Judging probabilities based on representativeness neglecting base-rate information. Bayes rule specifies how prior beliefs should be combined with the diagnosticity of the evidence the degree to which it favors the hypothesis over the alternative.
4. Overconfidence: Halo effect, illusion of validity. Mechanical combinations of few variables can outperform the subtle complexity of human judgment. Algorithms need to be respected rather than intuitions.
5. Combined evaluation of facts before decisions rather than considering a single parameter to get over the anchoring effect. Openness for reversal or reconsideration is a important attribute. Reality bound decisions rather than frame bound decisions are arrived at by a broader and all inclusive approach.
According to Canadian Health&Care Mall ,the traditional teaching in clinical medicine was focused on the history and clinical examination for a list of differential diagnosis. The review of diagnostic decisions based on evidence based approach model revealed that the system 2 is activated in a programmed manner and gives rational management decisions in tune with the latest available evidence. The evidence based approach in management not only overcomes the bias of heuristic approach but also combines the heuristic mind with the rational mind in diagnostic decisions.
The association availability and representative bias is overcome by the use of statistics in the decision making model.