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Journal of Evaluation in Clinical Practice ISSN 1365-2753
Medical and nursing diagnoses: a critical comparison Daniele Chiffi, PhD MSc MA1 and Renzo Zanotti RN PhD FEANS2 1 2
Postdoctoral Fellow, Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Padova, Italy Associate Professor, Department of Molecular Medicine, University of Padova, Padova, Italy
Keywords abduction, diagnosis, hypothesis, diagnostic reasoning, taxonomy Correspondence Prof. Renzo Zanotti Department of Molecular Medicine University of Padova Lab. of Nursing Studies via Loredan, 18–35121 Padova Italy E-mail: [email protected] Accepted for publication: 31 March 2014
Abstract Rationale Diagnostic systems exist in many disciplines. Strengths and weaknesses of such diagnostic systems vary considerably within and among disciplinary domains of the health sciences. The logical framework behind each diagnostic process involves identifying a condition, seeking causes, establishing a prognosis and a treatment. Notably, a clinical diagnosis is a judgment focused on the present, aiming to cluster events associated with a disease. Diagnostic judgment focuses on the past when it attempts to isolate possible causes, and towards the future when it indicates prognoses and treatments. Aims and objectives The paper suggests ways to differentiate nursing diagnosis from medical diagnoses, discussing ontology and abductive reasoning for doctors and nurses. Conclusions The proposed logical framework has been applied to a nursing taxonomybased diagnostic system in order to evaluate its strengths and weaknesses consistently with the epistemology of a diagnostic judgment.
doi:10.1111/jep.12146
Introduction Diagnosis is a key aspect of health care practice. The quality of diagnostic procedures has been acknowledged as an indication of the quality of health care as a whole [1] because appropriate diagnostics can avoid pointless treatments or mistreatments, and reduce unnecessary health care costs. A critical analysis of diagnostic procedures may thus be of theoretical interest and/or useful for empirical purposes. Diagnoses exist in many disciplines, and the strengths and weaknesses of diagnostic procedures can vary considerably in different domains of the health sciences. The term ‘diagnosis’ can be used to indicate either the outcome of a diagnostic process, or the set of the adopted process leading to the outcome; in this paper, the term ‘diagnosis’ mainly refers to a process. Our investigation aims to identify the epistemological and ontological differences existing between medical diagnoses and nursing diagnoses. The structure and goals of diagnosis are elucidated in the context of clinical knowledge. The logical framework behind every diagnostic process involves identifying a condition, seeking (possible) causes of a disease (or, more generally, some negative and troublesome event), establishing a plausible prognosis leading to an appropriate treatment. A clinical diagnosis naturally has different goals from other types of diagnosis, even though all diagnoses share the same logical structure (a critical investigation of nursing diagnoses is provided in the section ‘Nursing diagnosis’). The doctor’s and nurse’s different approaches to diagnostic considerations can be explained by referring to their two
Journal of Evaluation in Clinical Practice 21 (2015) 1–6 © 2014 John Wiley & Sons, Ltd.
different approaches to hypothetical reasoning (as provided in the section ‘Diagnostic hypotheses and abductive reasoning’) and ontologies. More specifically, the purpose of a medical diagnosis is to identify a biological alteration (be it organic or functional) and provide a possible helpful treatment, while a nursing diagnosis aims to enhance an individual’s self-care. The paper is organized in four sections and a conclusion, as follows: The second section deals with the foundations of medical diagnosis; The third section investigates the proprium of nursing diagnosis after a comparison with medical diagnosis; a critical discussion of this comparison between the two types of diagnosis in the light of abductive theory is provided in the fourth section; final epistemological considerations and ontological differences between medical and nursing diagnoses are highlighted in the Conclusion.
Medical diagnosis A diagnostic process involves a sequence of operations with a different timing, and different information stages and judgments. The structure of the diagnostic process can be described as follows. A diagnosis focuses on the present when its purpose is to acknowledge a cluster of events associated with a disease, while it focuses on the past when it attempts to isolate possible causes of a disease, but it is basically oriented towards the future when it indicates a possible prognosis and an appropriate treatment for a given patient. The aim of the diagnostic process is to formulate a clinical judgment in order to: (i) identify or rule out a disease; 1
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(ii) explain the findings and their likely causes to the patient; (iii) predict the disease’s course; and (iv) modify its predicted course [2]. We critically investigate all four goals of medical diagnostics. 1 A diagnosis reflects the existing medical knowledge on a given pathological condition [3], and has an evaluative dimension because the end product of the diagnostic process is a judgment, not just a description, and judgments need to be justifiable. Ideally, the identification and thorough understanding of a disease relies on a knowledge of the type of organic or functional alteration, its anatomopathological nature and causes, and some individual features of the patient concerned [4]. The causes of a disease may not be known, and the available knowledge might relate only to some associations that are considered as risk factors. Be that as it may, it is only when the causes of a disease have been ascertained scientifically that the doctor can acknowledge them [5]. Knowledge differs from acknowledgement. The doctor therefore has to choose from a finite number of hypotheses to reach a clinical judgment (in the section ‘Diagnostic hypotheses and abductive reasoning’, we call such an approach to hypothetical reasoning ‘inference to the best explanation’ or ‘abduction in the context of justification’). It seems that the doctor needs to know the causes of a disease, not to explain the pathological condition. An explanation functionally correlates two phenomena by means of some covering laws and initial conditions [6], whereas in medicine, causes are ascertained primarily on the strength of a codified knowledge of the physiopathological mechanism(s) contributing to the onset of a disease, although associated social, genetic or environmental factors cannot be ruled out. When certain symptoms frequently occur together and a common but unknown cause is assumed to induce them, then doctors call this condition a syndrome. Except in those pathognomonic situations, which are very unlikely to occur, in which patients present with a sign that is indicative of a given disease, doctors have to enumerate (at least partially) a finite number of possible hypotheses codified on the strength of medical knowledge and thus identify the most plausible hypothesis, H, to test. Then H is the object of an empirical assessment that may lead to its confirmation or rejection, or – more often than not – to the production of evidential (and probabilistic) support for it. An attempt at diagnostic verification strives to produce positive and conclusive evidence of a hypothesis, also seeking evidence to support the hypothesis in other organ systems. Likewise, a diagnosis may be reached by ruling out factors that imply the presence of a disease in order to reject a given hypothesis [7]. Either way, medical knowledge is gained under a veil of uncertainty, so the confirmation of a hypothesis takes place within a probabilistic framework. Doctors have to avoid creating new diagnostic hypotheses; they need to acknowledge (at least partially), enumerate and control them. Some hypotheses can be excluded from the diagnostic process, for instance, by means of laboratory tests and somatic analyses. The collection and investigation of notable signs (usually called anamnesis) must also be done in the light of a set of initial working hypotheses, otherwise operational errors are liable to affect the diagnostic process. Some examples of operational errors associated with the diagnostic process include those situations in which a diagnosis is unintentionally delayed (sufficient information was available earlier), wrong (a misdiagnosis is established before the right one), or missed (no diagnosis is made) [8]. In 2
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addition to the heuristics and biases associated with probabilistic reasoning in medicine [9], some diagnostic errors may relate to diagnostic uncertainty concerning: a disease’s definition; measurement errors; a lack of evidence of the clinical validity of a test or of the clinical utility of a treatment; failure to consider all the diagnostic possibilities; a different elicitation of experts’ beliefs; and so on [10]. All these aspects can be misleading and affect a doctor’s ability to arrive at a sound clinical judgment. 2 In ordinary medical communications, patients and health professionals may have diverging narrative attitudes to health problems, particularly in the time leading up to a diagnosis [11]. The patients’ attitude is oriented towards a biographical conceptualization of their illness, while the doctors’ attitude is more often characterized by a scientific knowledge-based approach. Clinical practice also has an ideographical dimension related to an individual’s human and social features, and this cannot be disregarded. Clinical activity is not a science, but an art, though it relies heavily on scientific outcomes and methods within a logical and probabilistic framework. It is quite common, in fact, for probabilities to be used when reporting a diagnosis to a patient because most diagnoses are uncertain and exposed to the risk of error. The (final) clinical probability of a diagnosis is ultimately placed in a Bayesian framework at the crossover point between the (initial) epidemiological incidence of a disease in a population of interest and the probability of the disease given the signs observed in a given patient. Note that incidences are frequencies, while the other probabilities express a degree of rational conviction, so it might not be easy to cope with different types of probabilities (as mentioned in [12]). Then, when it comes to communicating a diagnosis to a patient, there may be some cognitive biases due to the use of different types of probabilistic information, which can easily be misunderstood. 3 A diagnosis provides goal-oriented (teleological) knowledge. Forecasting the course of a disease in a given patient is a key ingredient of clinical practice. A medical diagnosis has to provide a teleological (functional) explanation for a health-related condition. According to Nagel [13], a function can be explained as follows: ‘the function A in a system S with organization C is to enable S in environment E to engage in process P; e.g. the heart has the function of pumping blood through the circulation system’. The alteration or loss of a health function are fundamentally important to a diagnostic judgment because a diagnosis has to (at least partially) predict the course of the patient’s disease (in association with the chosen therapy) on the basis of the available evidence of the patient’s health functions at the time. So, the notions of function, organization, environment and process are the key ingredients of teleological activities, and they are all time dependent. Problems in a biological system can be due to a malfunction of A, or to errors in the structure of the biological system S with organization C, negative conditions in the environment E, or procedural errors in P. Of course, the occurrence of these conditions may be nested, and not necessarily in any given order. In a biomedical functional explanation, our main concern is to maintain the organism in equilibrium, for example, the heart’s pumping action helps to keep the blood circulating and any change occurring in its circulation can deeply affect the health of the organism. 4 The predicted course of a disease can be changed appropriately if its causes are known, and providing we know how to modify the disrupted function. If this is not the case, doctors have
© 2014 John Wiley & Sons, Ltd.
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to modify a related health function that can favourably influence the situation [3]. In other words, many functions concur in keeping a biological system in good working order, so when doctors are unable to modify one function that is disturbed, then they have to prescribe treatments designed to enhance other normal functions. From this perspective, any decision to prescribe a therapy has to be rational and focus on the patient’s well-being. This can be achieved by interpreting the patient’s needs on the one hand, and by grounding the diagnosis on medical knowledge within a sound logical framework on the other. Errors made within the inferential framework of a diagnosis can stem not only from the adequacy of the doctor’s medical knowledge, but also from an unsound application of the laws of logic [3–14]. All four above-described goals of medical diagnosis have key epistemological issues that can be elucidated by means of a rational reconstruction of the clinical diagnostic reasoning process. In the light of our pre-theoretical insight, a medical diagnosis is the prototype of any diagnostic process in the minimal sense of the diagnosis identifying a condition, searching for its causes, forecasting its course and suggesting a treatment capable of modifying the prognosis. In the next section, we compare this medical diagnosis with a nursing diagnosis, going on to show that there is an urgent need for a sound epistemological methodology in nursing theory and practice too in order to make sense of the proprium of nursing.
Nursing diagnosis The nature of nursing diagnosis is an open issue. Different diagnostic systems are currently in the literature. The most commonly used worldwide is the NANDA (North American Nursing Diagnosis Association) system, followed by its European counterpart prepared by the ICNP (International Council of Nursing Practice) and a variety of other systems based on specific nursing theories [15–17]. In this paper, we restrict our discussion to the NANDA system alone. This diagnostic system is basically a taxonomy developed since 1973 for the purpose of identifying and justifying nursing activities, and adopting a standardized language for nursing diagnoses, interventions, and outcome definitions, as provided by the NNN (NANDA-NICNOC) association (web site: http://www.nanda.org/nanda-i-nicnoc.html). The NANDA defines a nursing diagnosis as ‘a clinical judgment about individual, family, or community experiences/ responses to actual or potential health problems/life processes. A nursing diagnosis provides the basis for selection of nursing interventions to achieve outcomes for which the nurse has accountability’ [18]. According to the NANDA, a diagnosis is closely associated with the responsibility for deciding and planning subsequent treatments. Consistently with the accepted paradigm of nursing [19], and unlike a medical diagnosis, a nursing diagnosis can be community-based. For instance, the diagnosis of an ‘ineffective relationship’ is defined as ‘a pattern of mutual partnership that is insufficient to provide for each other’s needs’. Such a diagnosis is family- or community-based, and not necessarily dependent on biological issues, since its defining characteristics are ‘inability to communicate in a satisfying manner between partners’, ‘no demonstration of mutual support in daily activities between partners’ and so on. This has huge consequences on the nature of diagnosis in nursing. For a start, a
© 2014 John Wiley & Sons, Ltd.
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nursing diagnosis does not aim to isolate a specific alteration by trying to acknowledge the causes of a functional or organic alteration (as in medical diagnoses), and it must not merely rename and mimic a medical diagnosis. Nursing theory tries to integrate clinical judgment with evidence belonging to the social, psychological, philosophical and anthropological disciplines. On the one hand, nursing provides a methodological interface between clinical, social and humanistic knowledge; on the other, nursing diagnoses try to address life processes taking place over time. Both medical and nursing diagnoses thus work in a tensed framework because they attempt to handle health-related processes properly in their temporal and teleological dimensions. Nursing diagnosis lacks certain ingredients, however, without which it cannot be considered a diagnosis per se: 1 a nursing diagnosis is often framed as a description of an individual’s behaviour or attitude rather than as a judgment that empirically correlates causes and effects; and 2 when a nursing diagnosis is unrelated to any biological alteration – as in the case of some forms of ‘urinary incontinence’, for instance – and there is no direct cause/effect relationship, then it seems more like a mere empirical generalization of certain observable circumstances than a judgment based on any causal laws. From 1 and 2, it follows that a nursing diagnosis without some form of causality has no predictive power and is consequently not a prognostic assessment. The fact that it is not based on causal laws implies that the hypothetical reasoning used in nursing is not just a matter of choosing and confirming hypotheses, as in medicine. The hypothetical reasoning used in nursing frequently deals with ‘hypothesis-candidates’ that may be only weakly supported by available evidence just because of this lower reliance on casual laws (in the section ‘Diagnostic hypotheses and abductive reasoning’, this type of hypothetical reasoning is called abduction in the context of discovery). A further weakness of the NANDA diagnostic system concerns the so-called ‘risk diagnoses’, for example, ‘Risk for ineffective relationship’, or ‘Risk for spiritual distress’. According to the NANDA system, a risk diagnosis is ‘a clinical judgment about human experiences/responses to health conditions/life principles that have a high probability of developing in a vulnerable individual, family, group or community’ ( [18] p. 96). If we do not wish to redefine the notions of diagnosis and risk, it is not really clear what a ‘risk diagnosis’ might be. Although there are many definitions of ‘risk’, the Royal Society of London defines it as ‘the probability of an event together with the probability of an (uncertain) outcome, which might occur during a determined time period, in combination with the magnitude of the effect and its consequences’ [20]. A ‘risk diagnosis’, again, does not follow the logic of an actual diagnosis because there is no acknowledgement of the individual’s present conditions. There is merely a judgment on possible future events that may or may not actually occur, relying on past causes of the condition to provide a future prognosis. If the purpose of a ‘risk diagnosis’ is to acknowledge a possible future condition, then – being already framed in the future – it cannot go on to predict a subsequent condition, in the sense of providing a prognosis. It seems that a ‘risk diagnosis’ is a prognosis used as a diagnosis without actually assessing the individual’s current situation. There are also some analytical problems in the so-called risk diagnoses, associated with the very notion of 3
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risk. Even if there is a high probability of a given event occurring (as indicated in the above-mentioned definition of ‘risk diagnosis’), this does not mean to say that the corresponding risk is necessarily high as well because the magnitude (e.g. the level of statistical association) or the consequences of such an event might be negligible. In general, the problematic aspects of nursing diagnoses relate to the difficulty of determining the prognosis and, as mentioned earlier, prognosis is a necessary part of every diagnosis. To overcome this problem and arrive at a sound, epistemologically based notion of nursing prognosis, we suggest that nursing prognosis can ideally entail choosing methods of care in order to help individuals or communities to achieve their maximal health potential in accordance with the health status of the individual, family and community concerned. By ‘health potential’ we mean an individual’s capacity to provide independently for their own quality of life, given their actual state of health [21]. We consider the notion of nurturing an individual’s health potential as referring to any action to enhance their ability to control their own life processes. Nurses need interdisciplinary knowledge, logical reasoning and clinical competence to deal with the care of the ‘whole person’. Unlike its medical counterpart, a nursing diagnosis does not seem to be generated by testing a pre-set array of possible hypotheses because there is not the same reliance on causal laws. There are different ontological dimensions associated with medicine and nursing that become evident in their respective diagnostic judgments, namely, a bio-functional normality in medicine, and independence in self-care in nursing. In the next section, we explore the epistemological differences between medical and nursing diagnoses on the basis of their different approach to hypothetical reasoning.
Diagnostic hypotheses and abductive reasoning Hypothetical reasoning finds many applications in medicine and nursing, especially in diagnostic and therapeutic settings [22]. Decision making is an important part of the diagnostic process, when choosing the most adequate hypotheses for identifying a patient’s disease (from among a finite number of known hypotheses consistent with pathological knowledge), and prescribing the most appropriate treatment after predicting the future course of the patient’s condition. This type of hypothetical reasoning has been called abductive reasoning [23]. According to Peirce, abduction differs from either induction or deduction, and can be formulated as follows: ‘The surprising fact, C, is observed. But if A were true, C would be a matter of course. Hence, there is reason to suspect that A is true’. The above structure of abductive arguments cannot be applied to classical deduction, which is a logical system where truth is transmitted with certainty from the premises to the conclusion. Peirce saw abduction as a logical procedure that holds in what we now call the ‘context of discovery’, that is, in the genesis of a scientific theory. Nowadays, logical reasoning is also part of the ‘context of justification’ of a theory. After Peirce, abduction in the context of justification (AJ) has come to be seen as a possible form of ‘inference to the best explanation of a theory’, that is, an inference that 4
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is justified by the hypothesis judged most adequate to explain a given phenomenon. AJ has an essential role in the medical diagnostic process, viz. when a selection is made from among a finite set of hypotheses justified by pathological and scientific knowledge [24]. Abduction in the context of discovery (AD) is naturally also acknowledged as a sort of heuristic principle orienting the adoption of some ‘hypothesis-candidate’, namely, statements that are not positively confirmed by the evidence but whose negation is unjustified (not proved). Doctors have to choose a working hypothesis from among a given finite set of possible hypotheses codified by clinical knowledge in order to make sense of a patient’s anamnestic cues. AD is more often employed by nurses, however, because a nursing diagnosis has a less codified epistemological dimension and it is more likely to be associated with conditions for which ‘there is no previously established principle or cause that explains the observed surprising phenomenon’ [25]. Nursing diagnosis aims to find new hypothesis-candidates in order to orient the provision of services and patient care. It is worth noting that an explanatory hypothesis H always has to be acknowledged before the conclusion of the abductive argument, so abduction is not really creative. Frankfurt in [26] made the point contrarily to Peirce that abduction does not create new hypotheses, it works as a filter for adopting good hypothesis-candidates to test. Abduction in the context of justification thus helps us to select hypotheses, while in the context of discovery, it selects hypothesiscandidates [27]. In nursing, abduction should serve in this selection function of hypothesis-candidates with a view to improving health care paths because there is no precise and codified scientific framework for nursing knowledge as it happens to be in the case of medical diagnostics, which is based on the methods and results of many different sciences. Some of the limitations of abductive reasoning applied to nursing, like those presented in [28] for instance, were investigated by Lipscomb [29]. It may be that many plausible hypotheses are involved in the formation of a nursing diagnosis, and that abduction alone cannot discriminate between them and assess them adequately (‘generality problem’). So the formation of a nursing diagnosis needs to be confirmed using deductive and inductive methods too, in an interplay between logical and quantitative disciplines. On this level, the formation of a nursing diagnosis has to be based on the choice of hypothesis-candidates that are not already justified on the mere selection of hypotheses drawn from a pre-established set of options, as happens in medical diagnoses. Beyond the use of sound hypothetical reasoning, nursing practice can be enhanced by improving the language of nursing diagnoses. It is true that efforts to standardize the language of nursing diagnoses have the merit of unifying nursing practice and thereby facilitating the clear communication of care plans to co-workers and patients [30]. On the other hand, such standardization in nursing comes up against the inextricable and delicate issue of how to provide care with a view to enhancing a patient’s health potential. What nurses need most is not a standardized terminology and procedure, but an approach to critical thinking that can make sense of patients’ different perspectives on life. Nurses do not need a set of professional rules to apply uncritically; they need to have a thorough understanding of nursing practice and to fine tune their critical and linguistic diagnostic skills in order to acknowledge good hypothesis-candidates.
© 2014 John Wiley & Sons, Ltd.
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Conclusion We have outlined the structure and goals of a diagnosis, and shown that there may be some overlaps between medical and nursing judgments. We have also indicated some ways to distinguish nursing diagnosis from medical diagnoses, discussing two different approaches to abductive reasoning for doctors and nurses. In other words, there is a difference between the diagnostic and interventional judgments made by nurses and doctors because they are likely to apply a different reasoning to their health-related hypotheses. In principle, a medical diagnosis can be established without the patient being actively involved because it is basically concerned with biological and functional alterations (as in emergency situations, for instance). A nursing diagnosis focuses instead on the patient’s social and humanistic domains (it is context related), so there can be no such diagnosis without the conscious participation of the individual concerned, or the family or the community. ‘This is because the focus of nursing care is the “whole person,” or persons’ achievement of well-being and self-actualization’ [31]. Without a patient’s participation, nursing can set no achievable goals of individual development, and nursing practice will consequently be reduced to the mere provision of supportive or substitutive care. With the patient’s active involvement, it becomes possible to identify and enhance their level of independence in self-care, and a nursing diagnosis can establish feasible goals for advanced nursing practices, whatever the patient’s medical diagnosis. The practical usefulness of a diagnosis lies in providing a judgment on a patient’s current situation and a prediction of potential developments in order to decide on appropriate intervention strategies. To sum up, we have critically investigated the taxonomy-based NANDA diagnostic system, which is meant to be practice oriented but lacks the epistemological requirements for a proper diagnostic judgment. Our discussion underscores that a nursing diagnosis should be much more than a mere descriptive algorithm to be applied uncritically. For it to enhance the quality of clinical decision making, a nursing diagnosis demands critical thinking, sound logical reasoning, and acknowledgement of the adequacy of (causal) hypotheses. We have pointed out that algorithmic and taxonomic decision making tools can help to support decisionmaking processes in the health care setting providing scientific and clinical knowledge are well founded, but they are no substitute for critical thinking when there are diverging hypotheses or ambiguous signs. In conclusion, medical and nursing diagnoses have different goals: a medical diagnosis identifies a variation from a norm, while a nursing diagnosis should judge the existence of a potential for enhancing self-care.
Acknowledgements This research was funded in part by a grant for the project ‘Decision Making and Argumentation in Medicine and Nursing Theory’ (University of Padova). The authors are grateful to Dario Gregori and Pierdaniele Giaretta for their critical comments and suggestions on this paper.
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Journal of Evaluation in Clinical Practice ISSN 1365-2753
Medical and nursing diagnoses: a critical comparison Daniele Chiffi, PhD MSc MA1 and Renzo Zanotti RN PhD FEANS2 1 2
Postdoctoral Fellow, Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Padova, Italy Associate Professor, Department of Molecular Medicine, University of Padova, Padova, Italy
Keywords abduction, diagnosis, hypothesis, diagnostic reasoning, taxonomy Correspondence Prof. Renzo Zanotti Department of Molecular Medicine University of Padova Lab. of Nursing Studies via Loredan, 18–35121 Padova Italy E-mail: [email protected] Accepted for publication: 31 March 2014
Abstract Rationale Diagnostic systems exist in many disciplines. Strengths and weaknesses of such diagnostic systems vary considerably within and among disciplinary domains of the health sciences. The logical framework behind each diagnostic process involves identifying a condition, seeking causes, establishing a prognosis and a treatment. Notably, a clinical diagnosis is a judgment focused on the present, aiming to cluster events associated with a disease. Diagnostic judgment focuses on the past when it attempts to isolate possible causes, and towards the future when it indicates prognoses and treatments. Aims and objectives The paper suggests ways to differentiate nursing diagnosis from medical diagnoses, discussing ontology and abductive reasoning for doctors and nurses. Conclusions The proposed logical framework has been applied to a nursing taxonomybased diagnostic system in order to evaluate its strengths and weaknesses consistently with the epistemology of a diagnostic judgment.
doi:10.1111/jep.12146
Introduction Diagnosis is a key aspect of health care practice. The quality of diagnostic procedures has been acknowledged as an indication of the quality of health care as a whole [1] because appropriate diagnostics can avoid pointless treatments or mistreatments, and reduce unnecessary health care costs. A critical analysis of diagnostic procedures may thus be of theoretical interest and/or useful for empirical purposes. Diagnoses exist in many disciplines, and the strengths and weaknesses of diagnostic procedures can vary considerably in different domains of the health sciences. The term ‘diagnosis’ can be used to indicate either the outcome of a diagnostic process, or the set of the adopted process leading to the outcome; in this paper, the term ‘diagnosis’ mainly refers to a process. Our investigation aims to identify the epistemological and ontological differences existing between medical diagnoses and nursing diagnoses. The structure and goals of diagnosis are elucidated in the context of clinical knowledge. The logical framework behind every diagnostic process involves identifying a condition, seeking (possible) causes of a disease (or, more generally, some negative and troublesome event), establishing a plausible prognosis leading to an appropriate treatment. A clinical diagnosis naturally has different goals from other types of diagnosis, even though all diagnoses share the same logical structure (a critical investigation of nursing diagnoses is provided in the section ‘Nursing diagnosis’). The doctor’s and nurse’s different approaches to diagnostic considerations can be explained by referring to their two
Journal of Evaluation in Clinical Practice 21 (2015) 1–6 © 2014 John Wiley & Sons, Ltd.
different approaches to hypothetical reasoning (as provided in the section ‘Diagnostic hypotheses and abductive reasoning’) and ontologies. More specifically, the purpose of a medical diagnosis is to identify a biological alteration (be it organic or functional) and provide a possible helpful treatment, while a nursing diagnosis aims to enhance an individual’s self-care. The paper is organized in four sections and a conclusion, as follows: The second section deals with the foundations of medical diagnosis; The third section investigates the proprium of nursing diagnosis after a comparison with medical diagnosis; a critical discussion of this comparison between the two types of diagnosis in the light of abductive theory is provided in the fourth section; final epistemological considerations and ontological differences between medical and nursing diagnoses are highlighted in the Conclusion.
Medical diagnosis A diagnostic process involves a sequence of operations with a different timing, and different information stages and judgments. The structure of the diagnostic process can be described as follows. A diagnosis focuses on the present when its purpose is to acknowledge a cluster of events associated with a disease, while it focuses on the past when it attempts to isolate possible causes of a disease, but it is basically oriented towards the future when it indicates a possible prognosis and an appropriate treatment for a given patient. The aim of the diagnostic process is to formulate a clinical judgment in order to: (i) identify or rule out a disease; 1
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(ii) explain the findings and their likely causes to the patient; (iii) predict the disease’s course; and (iv) modify its predicted course [2]. We critically investigate all four goals of medical diagnostics. 1 A diagnosis reflects the existing medical knowledge on a given pathological condition [3], and has an evaluative dimension because the end product of the diagnostic process is a judgment, not just a description, and judgments need to be justifiable. Ideally, the identification and thorough understanding of a disease relies on a knowledge of the type of organic or functional alteration, its anatomopathological nature and causes, and some individual features of the patient concerned [4]. The causes of a disease may not be known, and the available knowledge might relate only to some associations that are considered as risk factors. Be that as it may, it is only when the causes of a disease have been ascertained scientifically that the doctor can acknowledge them [5]. Knowledge differs from acknowledgement. The doctor therefore has to choose from a finite number of hypotheses to reach a clinical judgment (in the section ‘Diagnostic hypotheses and abductive reasoning’, we call such an approach to hypothetical reasoning ‘inference to the best explanation’ or ‘abduction in the context of justification’). It seems that the doctor needs to know the causes of a disease, not to explain the pathological condition. An explanation functionally correlates two phenomena by means of some covering laws and initial conditions [6], whereas in medicine, causes are ascertained primarily on the strength of a codified knowledge of the physiopathological mechanism(s) contributing to the onset of a disease, although associated social, genetic or environmental factors cannot be ruled out. When certain symptoms frequently occur together and a common but unknown cause is assumed to induce them, then doctors call this condition a syndrome. Except in those pathognomonic situations, which are very unlikely to occur, in which patients present with a sign that is indicative of a given disease, doctors have to enumerate (at least partially) a finite number of possible hypotheses codified on the strength of medical knowledge and thus identify the most plausible hypothesis, H, to test. Then H is the object of an empirical assessment that may lead to its confirmation or rejection, or – more often than not – to the production of evidential (and probabilistic) support for it. An attempt at diagnostic verification strives to produce positive and conclusive evidence of a hypothesis, also seeking evidence to support the hypothesis in other organ systems. Likewise, a diagnosis may be reached by ruling out factors that imply the presence of a disease in order to reject a given hypothesis [7]. Either way, medical knowledge is gained under a veil of uncertainty, so the confirmation of a hypothesis takes place within a probabilistic framework. Doctors have to avoid creating new diagnostic hypotheses; they need to acknowledge (at least partially), enumerate and control them. Some hypotheses can be excluded from the diagnostic process, for instance, by means of laboratory tests and somatic analyses. The collection and investigation of notable signs (usually called anamnesis) must also be done in the light of a set of initial working hypotheses, otherwise operational errors are liable to affect the diagnostic process. Some examples of operational errors associated with the diagnostic process include those situations in which a diagnosis is unintentionally delayed (sufficient information was available earlier), wrong (a misdiagnosis is established before the right one), or missed (no diagnosis is made) [8]. In 2
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addition to the heuristics and biases associated with probabilistic reasoning in medicine [9], some diagnostic errors may relate to diagnostic uncertainty concerning: a disease’s definition; measurement errors; a lack of evidence of the clinical validity of a test or of the clinical utility of a treatment; failure to consider all the diagnostic possibilities; a different elicitation of experts’ beliefs; and so on [10]. All these aspects can be misleading and affect a doctor’s ability to arrive at a sound clinical judgment. 2 In ordinary medical communications, patients and health professionals may have diverging narrative attitudes to health problems, particularly in the time leading up to a diagnosis [11]. The patients’ attitude is oriented towards a biographical conceptualization of their illness, while the doctors’ attitude is more often characterized by a scientific knowledge-based approach. Clinical practice also has an ideographical dimension related to an individual’s human and social features, and this cannot be disregarded. Clinical activity is not a science, but an art, though it relies heavily on scientific outcomes and methods within a logical and probabilistic framework. It is quite common, in fact, for probabilities to be used when reporting a diagnosis to a patient because most diagnoses are uncertain and exposed to the risk of error. The (final) clinical probability of a diagnosis is ultimately placed in a Bayesian framework at the crossover point between the (initial) epidemiological incidence of a disease in a population of interest and the probability of the disease given the signs observed in a given patient. Note that incidences are frequencies, while the other probabilities express a degree of rational conviction, so it might not be easy to cope with different types of probabilities (as mentioned in [12]). Then, when it comes to communicating a diagnosis to a patient, there may be some cognitive biases due to the use of different types of probabilistic information, which can easily be misunderstood. 3 A diagnosis provides goal-oriented (teleological) knowledge. Forecasting the course of a disease in a given patient is a key ingredient of clinical practice. A medical diagnosis has to provide a teleological (functional) explanation for a health-related condition. According to Nagel [13], a function can be explained as follows: ‘the function A in a system S with organization C is to enable S in environment E to engage in process P; e.g. the heart has the function of pumping blood through the circulation system’. The alteration or loss of a health function are fundamentally important to a diagnostic judgment because a diagnosis has to (at least partially) predict the course of the patient’s disease (in association with the chosen therapy) on the basis of the available evidence of the patient’s health functions at the time. So, the notions of function, organization, environment and process are the key ingredients of teleological activities, and they are all time dependent. Problems in a biological system can be due to a malfunction of A, or to errors in the structure of the biological system S with organization C, negative conditions in the environment E, or procedural errors in P. Of course, the occurrence of these conditions may be nested, and not necessarily in any given order. In a biomedical functional explanation, our main concern is to maintain the organism in equilibrium, for example, the heart’s pumping action helps to keep the blood circulating and any change occurring in its circulation can deeply affect the health of the organism. 4 The predicted course of a disease can be changed appropriately if its causes are known, and providing we know how to modify the disrupted function. If this is not the case, doctors have
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to modify a related health function that can favourably influence the situation [3]. In other words, many functions concur in keeping a biological system in good working order, so when doctors are unable to modify one function that is disturbed, then they have to prescribe treatments designed to enhance other normal functions. From this perspective, any decision to prescribe a therapy has to be rational and focus on the patient’s well-being. This can be achieved by interpreting the patient’s needs on the one hand, and by grounding the diagnosis on medical knowledge within a sound logical framework on the other. Errors made within the inferential framework of a diagnosis can stem not only from the adequacy of the doctor’s medical knowledge, but also from an unsound application of the laws of logic [3–14]. All four above-described goals of medical diagnosis have key epistemological issues that can be elucidated by means of a rational reconstruction of the clinical diagnostic reasoning process. In the light of our pre-theoretical insight, a medical diagnosis is the prototype of any diagnostic process in the minimal sense of the diagnosis identifying a condition, searching for its causes, forecasting its course and suggesting a treatment capable of modifying the prognosis. In the next section, we compare this medical diagnosis with a nursing diagnosis, going on to show that there is an urgent need for a sound epistemological methodology in nursing theory and practice too in order to make sense of the proprium of nursing.
Nursing diagnosis The nature of nursing diagnosis is an open issue. Different diagnostic systems are currently in the literature. The most commonly used worldwide is the NANDA (North American Nursing Diagnosis Association) system, followed by its European counterpart prepared by the ICNP (International Council of Nursing Practice) and a variety of other systems based on specific nursing theories [15–17]. In this paper, we restrict our discussion to the NANDA system alone. This diagnostic system is basically a taxonomy developed since 1973 for the purpose of identifying and justifying nursing activities, and adopting a standardized language for nursing diagnoses, interventions, and outcome definitions, as provided by the NNN (NANDA-NICNOC) association (web site: http://www.nanda.org/nanda-i-nicnoc.html). The NANDA defines a nursing diagnosis as ‘a clinical judgment about individual, family, or community experiences/ responses to actual or potential health problems/life processes. A nursing diagnosis provides the basis for selection of nursing interventions to achieve outcomes for which the nurse has accountability’ [18]. According to the NANDA, a diagnosis is closely associated with the responsibility for deciding and planning subsequent treatments. Consistently with the accepted paradigm of nursing [19], and unlike a medical diagnosis, a nursing diagnosis can be community-based. For instance, the diagnosis of an ‘ineffective relationship’ is defined as ‘a pattern of mutual partnership that is insufficient to provide for each other’s needs’. Such a diagnosis is family- or community-based, and not necessarily dependent on biological issues, since its defining characteristics are ‘inability to communicate in a satisfying manner between partners’, ‘no demonstration of mutual support in daily activities between partners’ and so on. This has huge consequences on the nature of diagnosis in nursing. For a start, a
© 2014 John Wiley & Sons, Ltd.
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nursing diagnosis does not aim to isolate a specific alteration by trying to acknowledge the causes of a functional or organic alteration (as in medical diagnoses), and it must not merely rename and mimic a medical diagnosis. Nursing theory tries to integrate clinical judgment with evidence belonging to the social, psychological, philosophical and anthropological disciplines. On the one hand, nursing provides a methodological interface between clinical, social and humanistic knowledge; on the other, nursing diagnoses try to address life processes taking place over time. Both medical and nursing diagnoses thus work in a tensed framework because they attempt to handle health-related processes properly in their temporal and teleological dimensions. Nursing diagnosis lacks certain ingredients, however, without which it cannot be considered a diagnosis per se: 1 a nursing diagnosis is often framed as a description of an individual’s behaviour or attitude rather than as a judgment that empirically correlates causes and effects; and 2 when a nursing diagnosis is unrelated to any biological alteration – as in the case of some forms of ‘urinary incontinence’, for instance – and there is no direct cause/effect relationship, then it seems more like a mere empirical generalization of certain observable circumstances than a judgment based on any causal laws. From 1 and 2, it follows that a nursing diagnosis without some form of causality has no predictive power and is consequently not a prognostic assessment. The fact that it is not based on causal laws implies that the hypothetical reasoning used in nursing is not just a matter of choosing and confirming hypotheses, as in medicine. The hypothetical reasoning used in nursing frequently deals with ‘hypothesis-candidates’ that may be only weakly supported by available evidence just because of this lower reliance on casual laws (in the section ‘Diagnostic hypotheses and abductive reasoning’, this type of hypothetical reasoning is called abduction in the context of discovery). A further weakness of the NANDA diagnostic system concerns the so-called ‘risk diagnoses’, for example, ‘Risk for ineffective relationship’, or ‘Risk for spiritual distress’. According to the NANDA system, a risk diagnosis is ‘a clinical judgment about human experiences/responses to health conditions/life principles that have a high probability of developing in a vulnerable individual, family, group or community’ ( [18] p. 96). If we do not wish to redefine the notions of diagnosis and risk, it is not really clear what a ‘risk diagnosis’ might be. Although there are many definitions of ‘risk’, the Royal Society of London defines it as ‘the probability of an event together with the probability of an (uncertain) outcome, which might occur during a determined time period, in combination with the magnitude of the effect and its consequences’ [20]. A ‘risk diagnosis’, again, does not follow the logic of an actual diagnosis because there is no acknowledgement of the individual’s present conditions. There is merely a judgment on possible future events that may or may not actually occur, relying on past causes of the condition to provide a future prognosis. If the purpose of a ‘risk diagnosis’ is to acknowledge a possible future condition, then – being already framed in the future – it cannot go on to predict a subsequent condition, in the sense of providing a prognosis. It seems that a ‘risk diagnosis’ is a prognosis used as a diagnosis without actually assessing the individual’s current situation. There are also some analytical problems in the so-called risk diagnoses, associated with the very notion of 3
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risk. Even if there is a high probability of a given event occurring (as indicated in the above-mentioned definition of ‘risk diagnosis’), this does not mean to say that the corresponding risk is necessarily high as well because the magnitude (e.g. the level of statistical association) or the consequences of such an event might be negligible. In general, the problematic aspects of nursing diagnoses relate to the difficulty of determining the prognosis and, as mentioned earlier, prognosis is a necessary part of every diagnosis. To overcome this problem and arrive at a sound, epistemologically based notion of nursing prognosis, we suggest that nursing prognosis can ideally entail choosing methods of care in order to help individuals or communities to achieve their maximal health potential in accordance with the health status of the individual, family and community concerned. By ‘health potential’ we mean an individual’s capacity to provide independently for their own quality of life, given their actual state of health [21]. We consider the notion of nurturing an individual’s health potential as referring to any action to enhance their ability to control their own life processes. Nurses need interdisciplinary knowledge, logical reasoning and clinical competence to deal with the care of the ‘whole person’. Unlike its medical counterpart, a nursing diagnosis does not seem to be generated by testing a pre-set array of possible hypotheses because there is not the same reliance on causal laws. There are different ontological dimensions associated with medicine and nursing that become evident in their respective diagnostic judgments, namely, a bio-functional normality in medicine, and independence in self-care in nursing. In the next section, we explore the epistemological differences between medical and nursing diagnoses on the basis of their different approach to hypothetical reasoning.
Diagnostic hypotheses and abductive reasoning Hypothetical reasoning finds many applications in medicine and nursing, especially in diagnostic and therapeutic settings [22]. Decision making is an important part of the diagnostic process, when choosing the most adequate hypotheses for identifying a patient’s disease (from among a finite number of known hypotheses consistent with pathological knowledge), and prescribing the most appropriate treatment after predicting the future course of the patient’s condition. This type of hypothetical reasoning has been called abductive reasoning [23]. According to Peirce, abduction differs from either induction or deduction, and can be formulated as follows: ‘The surprising fact, C, is observed. But if A were true, C would be a matter of course. Hence, there is reason to suspect that A is true’. The above structure of abductive arguments cannot be applied to classical deduction, which is a logical system where truth is transmitted with certainty from the premises to the conclusion. Peirce saw abduction as a logical procedure that holds in what we now call the ‘context of discovery’, that is, in the genesis of a scientific theory. Nowadays, logical reasoning is also part of the ‘context of justification’ of a theory. After Peirce, abduction in the context of justification (AJ) has come to be seen as a possible form of ‘inference to the best explanation of a theory’, that is, an inference that 4
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is justified by the hypothesis judged most adequate to explain a given phenomenon. AJ has an essential role in the medical diagnostic process, viz. when a selection is made from among a finite set of hypotheses justified by pathological and scientific knowledge [24]. Abduction in the context of discovery (AD) is naturally also acknowledged as a sort of heuristic principle orienting the adoption of some ‘hypothesis-candidate’, namely, statements that are not positively confirmed by the evidence but whose negation is unjustified (not proved). Doctors have to choose a working hypothesis from among a given finite set of possible hypotheses codified by clinical knowledge in order to make sense of a patient’s anamnestic cues. AD is more often employed by nurses, however, because a nursing diagnosis has a less codified epistemological dimension and it is more likely to be associated with conditions for which ‘there is no previously established principle or cause that explains the observed surprising phenomenon’ [25]. Nursing diagnosis aims to find new hypothesis-candidates in order to orient the provision of services and patient care. It is worth noting that an explanatory hypothesis H always has to be acknowledged before the conclusion of the abductive argument, so abduction is not really creative. Frankfurt in [26] made the point contrarily to Peirce that abduction does not create new hypotheses, it works as a filter for adopting good hypothesis-candidates to test. Abduction in the context of justification thus helps us to select hypotheses, while in the context of discovery, it selects hypothesiscandidates [27]. In nursing, abduction should serve in this selection function of hypothesis-candidates with a view to improving health care paths because there is no precise and codified scientific framework for nursing knowledge as it happens to be in the case of medical diagnostics, which is based on the methods and results of many different sciences. Some of the limitations of abductive reasoning applied to nursing, like those presented in [28] for instance, were investigated by Lipscomb [29]. It may be that many plausible hypotheses are involved in the formation of a nursing diagnosis, and that abduction alone cannot discriminate between them and assess them adequately (‘generality problem’). So the formation of a nursing diagnosis needs to be confirmed using deductive and inductive methods too, in an interplay between logical and quantitative disciplines. On this level, the formation of a nursing diagnosis has to be based on the choice of hypothesis-candidates that are not already justified on the mere selection of hypotheses drawn from a pre-established set of options, as happens in medical diagnoses. Beyond the use of sound hypothetical reasoning, nursing practice can be enhanced by improving the language of nursing diagnoses. It is true that efforts to standardize the language of nursing diagnoses have the merit of unifying nursing practice and thereby facilitating the clear communication of care plans to co-workers and patients [30]. On the other hand, such standardization in nursing comes up against the inextricable and delicate issue of how to provide care with a view to enhancing a patient’s health potential. What nurses need most is not a standardized terminology and procedure, but an approach to critical thinking that can make sense of patients’ different perspectives on life. Nurses do not need a set of professional rules to apply uncritically; they need to have a thorough understanding of nursing practice and to fine tune their critical and linguistic diagnostic skills in order to acknowledge good hypothesis-candidates.
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Conclusion We have outlined the structure and goals of a diagnosis, and shown that there may be some overlaps between medical and nursing judgments. We have also indicated some ways to distinguish nursing diagnosis from medical diagnoses, discussing two different approaches to abductive reasoning for doctors and nurses. In other words, there is a difference between the diagnostic and interventional judgments made by nurses and doctors because they are likely to apply a different reasoning to their health-related hypotheses. In principle, a medical diagnosis can be established without the patient being actively involved because it is basically concerned with biological and functional alterations (as in emergency situations, for instance). A nursing diagnosis focuses instead on the patient’s social and humanistic domains (it is context related), so there can be no such diagnosis without the conscious participation of the individual concerned, or the family or the community. ‘This is because the focus of nursing care is the “whole person,” or persons’ achievement of well-being and self-actualization’ [31]. Without a patient’s participation, nursing can set no achievable goals of individual development, and nursing practice will consequently be reduced to the mere provision of supportive or substitutive care. With the patient’s active involvement, it becomes possible to identify and enhance their level of independence in self-care, and a nursing diagnosis can establish feasible goals for advanced nursing practices, whatever the patient’s medical diagnosis. The practical usefulness of a diagnosis lies in providing a judgment on a patient’s current situation and a prediction of potential developments in order to decide on appropriate intervention strategies. To sum up, we have critically investigated the taxonomy-based NANDA diagnostic system, which is meant to be practice oriented but lacks the epistemological requirements for a proper diagnostic judgment. Our discussion underscores that a nursing diagnosis should be much more than a mere descriptive algorithm to be applied uncritically. For it to enhance the quality of clinical decision making, a nursing diagnosis demands critical thinking, sound logical reasoning, and acknowledgement of the adequacy of (causal) hypotheses. We have pointed out that algorithmic and taxonomic decision making tools can help to support decisionmaking processes in the health care setting providing scientific and clinical knowledge are well founded, but they are no substitute for critical thinking when there are diverging hypotheses or ambiguous signs. In conclusion, medical and nursing diagnoses have different goals: a medical diagnosis identifies a variation from a norm, while a nursing diagnosis should judge the existence of a potential for enhancing self-care.
Acknowledgements This research was funded in part by a grant for the project ‘Decision Making and Argumentation in Medicine and Nursing Theory’ (University of Padova). The authors are grateful to Dario Gregori and Pierdaniele Giaretta for their critical comments and suggestions on this paper.
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