THE DIAGNOSTIC PROCESS AND DIAGNOSTIC CLASSIFICATION- IN CHILD -PSYCHIATRY-DSM-III

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1 THE DIAGNOSTIC PROCESS AND DIAGNOSTIC CLASSIFICATION- IN CHILD -PSYCHIATRY-DSM-III Introduction Dennis P. Cantwell, M.D. Abstract. Confusion often exists between the reliability and validity of the diagnostic pro cess and the reliability and validity of a diagnostic system. The diagn ostic pro cess can answer man y qu estion s about an ind ividual child. Only one of these questions deals with the definition of the clinical syndrome(s) with which the child presents. These principles of classification as wel1 as others served as a guide in the development of the DSM-III classification of the disorders of infancy, childhood, and adolescence. Journal ofthe American Academy ofchild Psychiatry, 19: , THE DIAGNOSTIC PROCESS The diagnostic process in child psychiatry can be conceptualized as geared toward answering a number of questions (Cohen, 1976). These questions include: 1. Does the child who is being presented for evaluation have any type of psychiatric disorder? This question can be taken further: does the child have a significant problem in development-a problem that is manifested as an abnormality in behavior, emotions, relationships, or cognition; and one that is of sufficient severity and/or duration to cause distress, disability, or disadvantage? Dr. Cantwell was responsiblefor editing this speical section. He is Professor, Department of Psychiatry, UCLA Neuropsychiatric Institute, Th e Center fo r the Health Sciences (760 Westwood Plaza, Los Angeles, CA 90024), where reprints may be requested. This study was supported in part by the following grants: NIMH Special Research Fellowship IFOJMH , MH , MCH 927, and USPHS lrol, MH Al / $ C> 1980 American Academy of Child Psychiatry. GENERAL BOOKBINDING co 8' '6RA 013 ; _..-- x 345

2 346 Dennis P. Cantwell 2. Does the clinical picture of the child's disorder fit a known and recognized clinical syndrome? 3. Since all psychiatric disorders in childhood are probably of multifactorial etiology, what are the intrapsychic, familial, social, and biological roots of the disorders in the individual child, and what are the relative strengths of each of these roots? 4. What forces maintain the problem? 5. What forces facilitate the child's normal development? 6. What are the individual child's strengths and competencies? 7. Untreated, what will be the likely outcome of this child's disorder? The answer to this question depends partly on the natural history of the clinical syndrome described in the answer to question 2. It also depends on the answers to questions 3 to 6. The natural history of the child's disorder determines the urgency and level of intervention. Obviously, a disorder which will pass with time, leaving no residual effects, requires much less urgent and much less severe intervention than a disorder which is likely to be significantly disabling without treatment. The natural history of a child's disorder also offers a test of the efficacy of treatment. For a treatment to be considered efficacious, the outcome must be better than that which could be predicted on the basis of no treatment. 8. Is intervention necessary in this case? 9. What types of intervention are most likely to be effective? Treatment planning in child psychiatry depends not only on the answer to question 2-what diagnostic syndrome is the child suffering from-but also on the answers to questions 3 to 7. The tools available to the practitioner in the diagnostic process include: an interview with the parents about the child; family interviews; an interview with the child; behavior rating scales completed by parents, teachers, and significant others in the child's life; a physical exam; a neurological exam; and laboratory studies including psychological testing. Only in rare cases do the physical and neurological exam and laboratory studies, including psychological testing, contribute to making a specific diagnosis in child psychiatry (Gittelman, 1980). This does not mean that they do not play an important part in many cases in providing other information regarding the diagnostic formulation. Laboratory studies do not exist for the diagnosis of specific psychiatric disorders in childhood, with the exception of such things as chromosomal studies in certain cases of mental retardation, and specific psychometric testing for confirmation of the diagnosis of some specific developmental disorders.

3 The Diagnostic Process-Introduction 347 In general, the defining of a clinical syndrome in childhood is done on the basis of the interview with the parents, the interview with the child, and the behavior rating scales. In one of the few studies of the reliability and validity of the diagnostic procedures in child psychiatry, Rutter et al. (1970) found that the interview with the parents was the single best instrument for detecting children with psychiatric disorder. It was only rarely that children who were considered to be normal by their parents, and normal on the basis of parent-teacher rating scales, were considered to be psychiatrically disturbed by psychiatrists based solely on the interview with the child. The use of behavior rating scales has been fostered primarily in research settings, particularly in psychopharmacological research settings. However, clinicians who have used behavior rating scales in these settings have found them to be helpful in the diagnostic process even in nonresearch settings. It is the data from behavior rating scales generally completed by parents and teachers, and in other instances completed by mental health workers, that have led to the empirically derived syndromes of behavior described by Achenbach (1980). It is surprising how little work has been done on the reliability and validity of the diagnostic process in child psychiatry. PRINCIPLES OF CLASSlFICATION IN CHILD PSYCHIATRY The basic principles of classification in child psychiatry have been discussed fully by Rutter (1978a). The most important of these were: 1. There is no "right way" or "natural way" to classify the psychiatric disorders of childhood. Traditional classification systems, including DSM-I, DSM-II, GAP, and the newer DSM-III, have categorical classification systems. However, Achenbach (1980) has reviewed the evidence for the validity and stability of empirically defined syndromes of behavior produced by factor, pattern, and cluster analysis. Only some of these empirically derived syndromes have counterparts in DSM-III, although there does tend to be a large degree of overlap. There are empirically derived syndromes that have no apparent counterpart in DSM-III, and likewise there are DSM-III diagnostic categories that apparently have no counterpart among the empirically derived syndromes of behavior. There are multiple reasons why this may be so. Spitzer (1980) has stated that "no diagnostic category has ever been added to a classification

4 348 Dennis P. Cantwell of mental disorders for clinical use that was a syndrome first identified by a mathematical procedure designed to generate diagnostic categories." Etiology is not necessarily thebest basis for classification. Etiology is a good basis for classification in disorders due to specific bacterial agents which can be isolated and tested for sensitivity and treated with specific antibiotics. However, this is not necessarily so in the rest of general medicine. For example, a descriptive-phenomenological approach to fractures (simple versus compound) offers much more information than an etiological one which would state whether the fracture was due to having been hit with a hammer or by a car. 2. For any classification system to be successful, it must be based on facts and not on theoretical concepts. This is a particular difficulty in child psychiatry. There is a relative lack of hard concrete facts in child psychiatry regarding natural history, familial pattern ofillness, developmental changes in symptom pattern, etc., for various disorders. In child psychiatry, one man's fact is often considered another man's fantasy. 3. The diagnostic categories in the classification system must be reliable. A system cannot be valid if it is not reliable. Even if a classification system has reliability-that is, clinicians can agree with a high degree of reliability on diagnoses applied to a series of cases-it still may not have validity. Spitzer (1980) has pinpointed the major sources of unreliability in psychiatric diagnosis. These include: information variance, observation and interpretation variance, and criterion variance. Information variance arises from the fact that different clinicians evaluating the same case obtain different types of information on which to base their diagnosis. Observation and interpretation variance occurs when clinicians, even though they elicit the same information and make the same observations, differ in what they remember and in how they interpret whatthey see and hear. Criterion variance occurs when there are differences in the criteria that clinicians use to make a certain diagnosis. For example, if a child has hyperactivity, inattentiveness, and impulsive behavior, and also may have some conduct disorder symptoms, some clinicians will make both diagnoses of attention deficit disorder with hyperactivity and conduct disorder. Others will only make a diagnosis of conduct disorder and ignore the symptomatology of attention deficit disorder with hyperactivity. There is also subject variance and occasion variance because a

5 The Diagnostic Process-Introduction 349 patient may actually have a different condition at different times, and may present differently at different times. Technically these are also sources of unreliability in diagnosis; sirice these reflect true facts, however, they do not represent actual disagreement in diagnosis but represent a true change on the part of the patient (Spitzer, 1980). There are very few studies that have examined the relative contributions of information variance, criterion variance, and observation and interpretation variance to diagnostic unreliability. There is a study by Ward et al. (1962) of agreement between psychiatrists, using DSM-I as the diagnostic system, on the diagnosis of psychiatric disorders in adults. This study indicated that nearly two thirds of the diagnostic disagreements were due to criterion variance. Apparently, there are no comparable studies with children. Criterion variance can be minimized by the use of operational diagnostic criteria for each psychiatric disorder. Such criteria have been specified by Feighner et al. (1972) and by Spitzer et al. (1979) for psychiatric disorders in adults. The DSM-III classification of psychiatric disorders of both adults and children also specifies operational diagnostic criteria for each diagnosis. 4. The diagnostic categories 'must have validity. Spitzer (1980) has denoted the types of validity that should be distinguished when the validity of a classification system is being considered. These include: face validity, descriptive validity, predictive validity, and construct validity. Face validity is the first step in the indentification of a diagnostic category. One obtains descriptions from experienced clinicians about what they think the essential features of a particular disorder should be. Many of the categories in the childhood section have only face validity. Some have descriptive validity. As Spitzer and Cantwell (1980) point out, it is necessary initially to include categories which only have face validity; but if more powerful types of validity, such as descriptive validity and predictive validity, cannot be demonstrated after a thorough investigation, then the categories probably should not be continued in further editions of the classification system. When the category has descriptive validity, it justifies the assumption that this category represents a distinct behavioral syndrome rather than a random collection of clinical features. A category that has little descriptive validity is characterized by symptoms which are commonly seen in persons with other types of mental disorders or in persons with no mental disorder. From the clinical standpoint probably the most important type of

6 350 Dennis P. Cantwell validity is predictive validity-that is, how the various types of mental disorders described in the system differ in ways other than in their clinical picture. Such knowledge can be helpful in predicting natural history, biological correlates, differential responses to treatment, etc. In child psychiatry, to a much greater degree than in adult psychiatry, there are many categories that have little predictive validity. In child psychiatry, there is a relative lack of knowledge about the natural history of various psychiatric disorders both with and without treatment, and an even greater lack of knowledge regarding the response of different syndromes todifferent types of psychiatric intervention. 5. Any classification system classifies psychiatric disorders of childhood; it does not classify children. Thus, it is correct to say, "Tommy Jones has infantile autism." It is incorrect to say, "Tommy Jones, the autistic," just as it would be incorrect to say, "Tommy Jones, the diabetic." Clearly, in most psychiatric disorders of childhood, there is no homogeneity within a diagnostic category. The diagnostic classification system classifies disorders, and it is not equivalent to a diagnostic formulation. A diagnostic classification system tells us what patients have in common with other patients who have similiar clinical syndromes. A diagnostic formulation tells us what makes patient A different from patient B, even though they have the same clinical syndrome. 6. To be clinically useful, a classification system must provide adequate differentiation and adequate coverage. The "ultimate system" would be both jointly exhaustive and mutually exclusive. A patient would present with only one disorder, and all patients who walk through our doors would have disorders that are described somewhere within the system. We know from studies of adult psychiatric patients that as many as 25% receive a diagnosis of "undiagnosed mental disorder" (Goodwin and Guze, 1979). Studies that have used similar criteria for adolescents (Weiner et al, 1979). suggest that the figure is even higher. In addition to providing adequate coverage, the system must provide adequate differentiation between syndromes. An overall rubric such as "adjustment reaction of childhood" may cover nearly every child who comes through our doors. It is obviously useless for differentiation between syndromes that require differential types of intervention or have different natural histories without treatment.. 7. It must be recognized that psychiatric disorders in childhood do not exist as discrete entities with complete discontinuity between

7 The Diagnostic Process-Introduction 351 one disorder and another disorder, and complete discontinuity between the category of psychiatric disorder and normality (Spitzer, 1980). This is very similar to what is found in general medicine with categories such as essential hypertension. That there is not a complete discontinuity between disorders and between a category of psychiatric disorder and normality does not obviate the usefulness and need for a classification system (Spitzer, 1980). 8. In contrast to a classification system of psychiatric disorders of adult life, a child psychiatric classification system must have a developmental framework. Much more is known about the traditional, well-described syndromes seen in adults such as schizophrenia and affective disorder. However, child psychiatrists see a number of conditions which: are considered normal at one time of life but may be pathological at another. (For example, bedwetting at age 2 versus bedwetting at age 12.) While all of psychiatry must contend with the question of distinguishing abnormality from normality, the child psychiatrist has the added problem of defining normality for different ages and developmental levels. 9. Finally, and most importantly, for a diagnostic classification system in child psychiatry to be worthwhile, it must be practical and clinically useful in everyday clinical practice. While it is true that diagnostic classification systems have multiple purposes, the most important one is clinical usefulness. Certainly, a classification system is a vitally necessary basis for communication in child psychiatry which has many divergent etiologic viewpoints. A classification system is useful for information retrieval, prediction, developing concepts to be used within a scientific discipline, and forensic and legal uses. But the system cannot be so complicated and so hard to use that mental health practitioners will avoid using it in everyday clinical practice. DIFFERENTIAL DIAGNOSIS Part of the diagnostic process in child psychiatry described above involves differential diagnosis, that is, distinguishing between the various disorders which may present with similar symptoms. In addition, differential diagnosis involves sorting out the different possible etiological factors that may lead to the same symptom. Lewis (1979) has provided a clear description of the type of process that goes into differentiating between the various causes of the same symptom, and Rutter (l978b) has given a clear overview of the current state of differential diagnosis of the various syndromes of child psychiatry.

8 352 Dennis P. Cantwell Most categorical diagnostic systems, including DSM-III, provide initial differential diagnosis between syndromes on the basis of. clinical symptomatology. That is, certain key essential features are present in one disorder that are not present in another, despite the degree of overlap in associated or secondary symptomatology. The categ-ory of infantile autism is well disting-uished from the category of schizophrenia not only on the basis of clinical symptomatology and earlier age of onset, but also on the basis of natural history, family history of schizophrenia, and response to phenothiazine medication. However, the differentiation between infantile autism and other forms of pervasive developmentaldisorders is not that clear-cut. It requires further research, as does the differentiation between pervasive developmental disorder, childhood onset, and the adult form of schizophrenia. There is good evidence for differentiation between broad groups of syndromes described as "behavioral" disorders versus "emotional" or "neurotic" disorders. Besides being distinguished on symptomatology (behavioral disorders presenting with such symptoms as aggressive behavior, hyperactivity, truancy, and the like, and emotional disorders presenting with anxieties, fears, phobias, etc.), these two broad groups of disorders differ in a variety or' other ways. The sex ratio is predominantly male in behavior disorders of childhood, while approximately equal in emotional disorders. Behavior disorders are characterized by a different family pattern of psychiatric illness, mainly.those in the antisocial spectrum: delinquency, antisocial personality, alcohol and drug abuse, and also by a greater correlation with marked family discord. The emotional disorders have a better prognosis in adolescence and adult life; and when they are associated with development of psychiatric disorder in adult life, it is usually a neurotic disorder or an. affective disorder, in contrast to the antisocial spectrum of disorders, which are associated with the behavior disorders of childhood. However, distinguishing between the subcategories of behavior disorders in childhood is still a controversial question. There are those who feel that attention deficit disorder with hyperactivity is a unique syndrome which is separate from other forms of conduct disorder, while those on the British sideofthe Atlantic tend to feel that it may be simply a variant ofconduct disorder. The subdivision of the conduct disorders in DSM-IlI according to.the degree of socialization and pattern of aggressive behavior is also a controversial issue. Even more controversial is whether or not the various subdivisions of emotional disorders of

9 The Diagnostic Process-Introduction 353 childhood have any diagnostic validity; that is, do the conditions differ in any way other than in their presenting symptomatology? Further research in this area is needed. SUMMARY AND CONCLUSIONS The diagnostic process and the principles of classification in child psychiatry have been reviewed. There is often a confusion between the reliability and validity of the diagnostic process and the reliability and validity of a diagnostic classification system. The diagnostic process is geared toward answering many questions about an individual child. Only one of these questions has to do with the definition of the clinical syndrome(s) with which the child presents. Surprisingly little work has gone into studying the reliability and validity of the diagnostic process in child psychiatry. The use of structured interviews such as the Schedule for Affective Disorders and Schizophrenia (SADS), Present State Exam (PSE), and the Diagnostic Interview Schedule (DIS) have improved reliability and validity of the process of psychiatric diagnosis with adults. The development of such instruments in child psychiatry is in its infancy. The Feighner criteria and the Research Diagnostic Criteria (RDC) likewise have led to improved reliability and validity of diagnostic categoreis with adults. The DSM-III system is the first attempt to specify operational criteria for diagnosis of disorders of infancy, childhood, and adolescence. One hopes that research in child psychiatry will be advanced by the use of these criteria in the same way that clinical research in adult psychiatry was advanced by the RDC and Feighner criteria. The papers that follow in this special section on psychiatric diagnosis in childhood cover four important and related topics. In the first paper, Spitzer and Cantwell discuss the DSM-III classification of the psychiatric disorders of childhood. They first review the basic features of the DSM-III classification, particularly the many unique features present for the first time in the classification system such as operational diagnostic criteria for each disorder. They then review the specific conditions described in the DSM-III section on Disorders Usually First Evident in Infancy, Childhood, or Adolescence, and they compare and contrast the DSM-III and the DSM-II classifications of psychiatric disorders of childhood. In the second paper, Rutter and Shaffer give a critique of the

10 354 Dennis P; Cantwell DSM-III classification of the psychiatric disorders of childhood. They point out what they see as the positive aspects pf this system and what they consider to be problem areas, particularly as the DSM-III system relates to the 9th edition of the International Classification of Diseases. In the third paper, Achenbach describes syndromes of childhood behavior empirically derived by multivariate statistical methods such as factor and cluster analysis. He points to the DSM-III counterparts for some of these empirically derived syndromes of behavior that appear to have no DSM-III counterpart, and to DSM~III disorders which apparently have no counterpart inthe empirically derived syndromes that have been described thus far. He views the two approaches to the classification of psychiatric disorders of childhood as complementary and points to the need for studies comparing the predictive power of both the DSM-III categorical syndromes and the empirically derived syndromes of behavior. In the last paper in this special section, Gittelman reviews the utility of certain psychological tests in the diagnosis of childhood psychiatric disorders. Since child psychiatry lacks laboratory findings for the majority of psychiatric disorders, reliance has often been placed on test profiles in making such diagnoses. Her data suggest that diagnosis in child psychiatry remains basically a clinical exercise, and that one will not obtain much help in this exercise from utilizing projective psychological tests. REFERENCES ACHENBACH, T. M. (1980), DSM-III in light of empirical research on the classification of child psychopathology. This Journal, 19: COHEN, D. J. (1976), The diagnostic process in child psychiatry. Psychiat. Ann., 6(9): FEIGHNER, J. P., ROBINS, E., GUZE, S. B., WOODRUFF, R. A., WINOKUR, G., & MUNOZ, R. (1972), Diagnositc criteria for use in psychiatric research. Arch. Gen. Psychiat., 26: GITTELMAN, R. (1980), Projective psychological tests and psychiatric diagnosis in children. This Journal, 19: GOODWIN, D. W. & GUZE, S. B. (1979), Psychiatric Diagnosis. New York: Oxford University Press. LEWIS, M. (1979), Differential diagnosis. In: Basic Handbook of Child Psychiatry, ed. J. D. Noshpitz,J. D. Call, R. L. Cohen, & I. N. Berlin. New York: Basic Books, 1: RUTTER, M. (1978a), Classification. In: Child Psychiatry, ed. M. Rutter & L. Hersov. London: Blackwell Scientific Publications, pp (1978b), Diagnostic validity in child psychiatry. Adv. Biol. Psychiat., 2: & SCHOPLER, E. (1978), Autism. New York: Plenum. -- TIZARD,J, & WHITMORE, K. (1970), Education, Health and Behavior. New York: Wiley; SPITZER, R. L. (1980), Classification of mental disorders.and DSM-III. In: Comprehensive

11 The Diagnostic Process-Introduction 355 Textbook cifpsychiatry III, ed. H. I. Kaplan, A. M. Freedman, & B. J. Sadock. Baltimore: Williams & Wilkins (in press). -- & CANTWELL, D. P. (1980), The DSM-IlI classification of the psychiatric disorders of infancy, childhood, and adolescence. ThisJournal, 19: ENDICOTT, J., & GIBSON, M. (1979), Crossing the border into borderline personality and borderline schizophrenia. Arch. Gen. Psychiat., 36: WARD, C. H., BECK, A. T., MENDELSON, M., MOCK, J. E., & ERBAUGH, J. K. (1962), Reasons for diagnostic disagreement. Arch. Gen. Psychait., 7: WELNER, A., WELNER, Z., & FISHMAN, R. (1979), Psychiatric adolescent inpatient. Arch. Gen. Psychiat., 36: