ADVANCED ASSESSEMENT INTERPRETING FINDINGS AND FORMULATING DIFFERENTIAL 4E

Chapter 1 Assessment and Clinical Decision Making: An Overview Mary Jo Goolsby • Laurie Grubbs • Clinical decision making is often fraught with uncertainties. According to a recent report (Bernstein, 2017), over 20% of persons presenting for second opinions in one facility had been misdiagnosed. Pat Croskerry (2013) estimates that the diagnostic failure rate is as high as 15%. Te “Augenblick diagnosis” is one made within “the blink of an eye” based on intuition, and it is a clinically dangerous state (p. 2445). While it works the majority of the time for experienced clinicians, it fails more often than we recognize. Croskerry (2013) describes two major types of clinical diagnostic decision making: intuitive and analytical. Intuitive decision making is consistent with the Augenblick diagnosis, in that the clinician relies on experience and intuition and the diagnosis occurs rapidly and with little effort. However, as noted, this type of decision making is less reliable and paired with fairly common errors. In contrast, analytical decision making is based on careful consideration, takes more time and effort, and has greater reliability with rare errors. Because practice settings present a number of distractors and competing demands, it is critical that diagnosticians step back, assess their processes and the data they are gathering, and attend to the possibilities. Diagnostic reasoning involves a complex process that is quickly clouded by first impressions. Te need to ensure necessary “data” requires a measured approach, even when faced with common complaints such as chest pain. Tis requires a consistent and measured approach to symptom analysis, physical assessment, and data analysis. Expert diagnosticians are able to maintain a degree of suspicion throughout the assessment process, consider a range of potential explanations, and then generate and narrow their differential diagnosis on the basis of their previous experience, familiarity with the evidence related to various diagnoses, and understanding of their individual patient. Trough the process, clinicians perform assessment techniques involving both the history and physical 01_Goolsby_C 3 27/10/18 12:46 pm 4 Advanced Assessment | The Art of Assessment and Clinical Decision Making examination in an effective and reliable manner and then select appropriate diagnostic studies to support their assessment. Te importance of diagnostic reasoning and expertise is gaining recognition. Te Society to Improve Diagnosis in Medicine () offers a number of resources for clinicians and educators, designed to address diagnostic error. History Among the assessment techniques essential to valid diagnosis is performing a fact-finding history. To obtain adequate history, providers must be well organized, attentive to the patient’s verbal and nonverbal language, and able to accurately interpret the patient’s responses to questions. Rather than reading into the patient’s statements, they clarify any areas of uncertainty. Te expert history, like the expert physical examination, is informed by the knowledge of a wide range of conditions, their physiological bases, and their associated signs and symptoms. Te ability to draw out descriptions of the patient’s symptoms and experiences is important because only the patient can tell his or her story. To assist the patient in describing a complaint, a skilful interviewer knows how to ask salient and focused questions to draw out necessary information without straying (i.e., avoiding a shotgun approach, with lack of focus). Te provider should know, based on the chief complaint and any preceding information, what other questions are essential to the history. It is important to determine why the symptom brought the patient to the office—that is, the significance of this symptom to the patient, which may uncover the patient’s anxiety and the basis for his or her concern. It may also help to determine severity in a stoic patient who may underestimate or underreport symptoms. Troughout the history, it is important to recognize that patients may forget details, so probing questions may be necessary. Patients sometimes have trouble finding the precise words to describe their complaint. However, good descriptors are necessary to isolate the cause, source, and location of symptoms. Often, patients must be encouraged to use common language and terminology. For instance, encourage the patient to describe the problem just as he or she would describe it to a relative or neighbor. Te history should include specific components (summarized in Table 1.1) to ensure that the problem is comprehensively evaluated. Te questions to include in each component of the history are described in detail in subsequent chapters. Content on communicating with patients who have physical communication deficits is provided in Chapter 22. However, clinicians may encounter patients who communicate using different languages. In these instances, alternative communication methods are critical in obtaining a necessary health history to support a valid assessment and diagnosis. 01_Goolsby_C 4 27/10/18 12:46 pm Chapter 1 | Assessment and Clinical Decision Making: An Overview 5 When the patient speaks a different language from the interviewer, an interpreter who is fluent in the languages of both the patient and the provider must be called upon. Te interpreter should be impartial and have experience in interpreting health-related information and understand the importance of confidentiality and accurately conveying each party’s communication. Te patient’s permission is needed prior to involving an interpreter. When using an interpreter, questions should be as succinct as possible and understanding should be validated by the interpreter. Te clinician should face and speak to the patient, rather than to the interpreter, being sensitive to body language and expressions. Component Purpose Chief complaint To determine the reason patient seeks care. Important to consider using the patient’s terminology. Provides “title” for the encounter. History of present illness To provide a thorough description of the chief complaint and current problem. Suggested format: P-Q-R-S-T. • P: precipitating and palliative factors To identify factors that make symptom worse and/or better; any previous self-treatment or prescribed treatment; and response. • Q: quality and quantity descriptors To identify patient’s rating of symptom (e.g., pain on a 1–10 scale) and descriptors (e.g., numbness, burning, stabbing). • R: region and radiation To identify the exact location of the symptom and any area of radiation. • S: severity and associated symptoms To identify the symptom’s severity (e.g., how bad at its worst) and any associated symptoms (e.g., presence or absence of nausea and vomiting associated with chest pain). • T: timing and temporal descriptions To identify when complaint was frst noticed; how it has changed/progressed since onset (e.g., remained the same or worsened/improved); whether onset was acute or chronic; whether it has been constant, intermittent, or recurrent. Past medical history To identify past diagnoses, surgeries, hospitalizations, injuries, allergies, immunizations, current medications. Habits To describe any use of tobacco, alcohol, drugs, and to identify patterns of sleep, exercise, etc. Sociocultural To identify occupational and recreational activities and experiences, living environment, fnancial status/support as related to health-care needs, travel, lifestyle, etc. Family history To identify potential sources of hereditary diseases; a genogram is helpful. The minimum includes frst-degree relatives (i.e., parents, siblings, children), although second and third orders are helpful. Review of systems To review a list of possible symptoms that the patient may have noted in each of the body systems. Table 1.1 Components of History 01_Goolsby_C 5 27/10/18 12:46 pm 6 Advanced Assessment | The Art of Assessment and Clinical Decision Making Physical Examination Te expert diagnostician must also be able to accurately perform a physical assessment. Extensive, repetitive practice; exposure to a range of normal variants and abnormal findings; and keen observation skills are required to develop physical examination proficiency. Each component of the physical examination must be performed correctly to ensure that findings are as valid and reliable as possible. Chapter 22 describes assessment of patients with physical disabilities. While performing the physical examination, the examiner must be able to • differentiate between normal and abnormal findings. • recall knowledge of a range of conditions, including their associated signs and symptoms. • recognize how certain conditions affect the response to other conditions in ways that are not entirely predictable. • distinguish the relevance of varied abnormal findings. Te aspects of physical examination are summarized in the following chapters using a systems approach. Each chapter also reviews the relevant examination for varied complaints. Along with obtaining an accurate history and performing a physical examination, it is crucial that the clinician consider the patient’s vital signs, general appearance, and condition when making clinical decisions. Diagnostic Studies Te history and physical assessment help to guide the selection of diagnostic studies. Diagnostic studies should be considered if a patient’s diagnosis remains in doubt following the history and physical. Tey often help establish the severity of the diagnosed condition or rule out conditions included in the early differential diagnosis. Just as the history should be relevant and focused, the selection of diagnostic studies should be judicious and directed toward specific conditions under consideration. Te clinician should select the study (or studies) with the highest degree of sensitivity and specificity for the target condition while also considering cost-effectiveness, safety, and degree of invasiveness. Selection of diagnostics requires a range of knowledge specific to various studies and the ability to interpret the study’s results. Resources are available to assist clinicians in the selection of diagnostic studies. For example, the American College of Radiology’s Appropriateness Criteria provides guidelines on selecting imaging studies (see the selection of laboratory studies. Subsequent chapters identify specific studies that should be considered for varied complaints, depending on the conditions included in the differential diagnosis. Diagnostic Statistics In the selection and interpretation of assessment techniques and diagnostic studies, providers must understand and apply some basic statistical concepts, 01_Goolsby_C 6 27/10/18 12:46 pm Chapter 1 | Assessment and Clinical Decision Making: An Overview 7 including the tests’ sensitivity and specificity, the pretest probability, and the likelihood ratio. Tese characteristics are based on population studies involving the various tests, and they provide a general appreciation of how helpful a diagnostic study will be in arriving at a definitive diagnosis. Each concept is briefly described in Table 1.2. Detailed discussions of these and other diagnostic statistics can be found in numerous reference texts. Bayes’s theorem is frequently cited as the standard for basing a clinical decision on available evidence. Te Bayesian process involves using knowledge of the pretest probability and the likelihood ratio to determine the probability that a particular condition exists. Given knowledge of the pretest probability and a particular test’s associated likelihood ratio, providers can estimate posttest probability of a condition based on a population of patients with the same characteristics. Post-test probability is the product of the pretest probability and the likelihood ratio. Nomograms are available to assist in applying the theorem to Statistic Description Sensitivity The percentage of individuals with the target condition who would have an abnormal, or positive, result. Because a high sensitivity indicates that a greater percentage of persons with the given condition will have an abnormal result, a test with a high sensitivity can be used to rule out the condition for those who do not have an abnormal result. For example, if redness of the conjunctiva is 100% sensitive for bacterial conjunctivitis, then conjunctivitis could be ruled out in a patient who did not have redness on examination. However, the presence of redness could indicate several conditions, including bacterial conjunctivitis, viral conjunctivitis, corneal abrasion, or allergies. Specifcity The percentage of healthy individuals who would have a normal result. The greater the specifcity, the greater the percentage of individuals who will have negative, or normal, results if they do not have the target condition. If a test has a high level of specifcity so that a signifcant percentage of healthy individuals are expected to have a negative result, then a positive result would be used to “rule in” the condition. For example, if a rapid strep screen test is 98% specifc for streptococcal pharyngitis and the person has a positive result, then he or she has “strep throat.” However, if that patient has a negative result, there is a 2% chance that the patient’s result is falsely negative, so the condition cannot be entirely ruled out. Pretest probability Based on evidence from a population with specifc fndings, this probability specifes the prevalence of the condition in that population, or the probability that the patient has the condition on the basis of those fndings. Likelihood ratio This is the probability that a positive test result will be associated with a person who has the target condition and a negative result will be associated with a healthy person. A likelihood ratio above 1.0 indicates that a positive result is associated with the disease; a likelihood ratio less than 1.0 indicates that a negative result is associated with an absence of the disease. Likelihood ratios that approximate 1.0 provide weak evidence for a test’s ability to identify individuals with or without a condition. Likelihood ratios above 1.0 or below 0.1 provide stronger evidence relative to the test’s predictive value. The ratio is used to determine the degree to which a test result will increase or decrease (from the pretest probability) the likelihood that an individual