Dimensional and Categorical Approaches to the Diagnosis of Attention Deficit Disorder in Children

Transcription

1 Dimensional and Categorical Approaches to the Diagnosis of Attention Deficit Disorder in Children W. O. SHEKIM, M.D., D. P. CANTWELL, M.D., J. KASHANI, M.D., N. BECK, M.D., J. MARTIN, M.A., J. ROSENBERG, M.Sc. AND The authors compared two approach methods for the diagnosis of attention deficit disorder with hyperactivity (ADDH) in a sample of year-old children in the community. One method was the categorical approach using a structured interview of parents about their children (DISC-P) and the other was the dimensional approach using Achenbach's Child Behavior Checklist (CBCL) filled in by the parents. There were 14 children diagnosed as having ADDH by DISC-P. Of these, two were "diagnosed" by CBCL. The children diagnosed as ADDH by DISC-P differed on the Achenbach's Externalizing factors from the children who did not have any DSM-III diagnosis by DISC-P and from those who had other DSM-III diagnoses; and on the Achenbach's Internalizing Factors they only differed from the children with no diagnosis and not from children with other diagnoses. Finally it is concluded that it is unlikely that a single cut-off score on any rating scale will be an adequate substitute for a systemic evaluation using several data sources. Journal of the American Academy of Child Psychiatry, 25, 5: , Since the publication of DSM-III, there has been renewed interest in the process involved in diagnosing childhood psychopathology and in the diagnostic classification of children's psychiatric disorders. DSM-III is a categorical system, and it provides explicit diagnostic criteria for the diagnosis of each psychiatric disorder listed in the childhood section of the manual. An alternative method of classification and diagnosis, which some feel is more objective and quantifiable, is a dimensional or factorial approach. The purpose of this paper is to compare both the categorical approach and the dimensional approach in the diagnosis of the attention deficit disorder with hyperactivity (ADDH) syndrome in a sample of 9-year-old children in the general population. old children and their parents served as subjects. Names were selected from public school registers in two rural midwestern counties; parents were phoned and asked to participate. The compliance rate was 55%. In order to ensure that the sample contained a representative portion of institutionalized or special school children whose names do not typically appear on public school registers, a search was made for treatment facilities and for other institutions specializing in the treatment and management of such individuals throughout the regions from where school registers were selected. This procedure resulted in the identification of 21 names representing approximately 3% of the total 9-year-old population. A number of these children were subsequently interviewed, and three of them were chosen at random and were included in the overall sample. Interviews took place at the subject's home, with the exception of eight families who were interviewed and videotaped at the facility in order to be interviewed while being videotaped. Subjects were provided with $10 payment for their participation. Two instruments were used; both tapped parents as the sole source of information. One was the Diagnostic Interview Schedule DISC (the DISC-P) developed by Costello and his associates (Costello et ai., 1982). The parent version of the DISC (the DISC-P) was used to systematically interview the parent about their child in order to enable the interviewers to make accurate diagnoses of children according to the DSM-III criteria. The DISC-P consists of 302 items and takes about 1lf2 hours to complete. The instrument is designed to Method The study was approved by the Human Experimentation Committee. One hundred and fourteen 9-yearReceived Dec. ](), 19H4; revised May 21, 1985; accepted Sept. 25, Dr. Shekim and Dr. Cantwell are with the Division of Mental Retardation and Child Psychiatry at the University of California at Los Angeles, Neuropsychiatric Institute, where Dr. Shekim is Associate Professor and Director, Child Ambulatory Care Services, and Dr. Cantwell is Joseph Campbell Professor of Child Psychiatry and Director of Residency Training in Child Psychiatry. Drs. Kashani and Beck, Mr. Martin and Miss Rosenberg are with the Department of Psychiatry, University of Missouri-Columbia and Mid-Missouri Mental Health Center, where Dr. KaBhani is Professor and Director, Children's Services, Dr. Beck is Associate professor and Director of Research, Mr. Martin is Director of Therapeutic Education and Ms. Rosenberg is Research Assistant. Send requests for reprints to Dr. Shekim, UCLA Neuropsychiatric In.~titute, 760 Westwood Plaza, Los Angeles, CA Supported in part by grant from the Kwan family to Dr. Walid O. Shekim /86/ $02.00/0 (C) 1986 by the American Academy of Child Psychiatry. 653

2 654 SHEKIM ET AL. be used by clinicians and lay interviewers alike. It employs the no/sometimes/yes answer pattern that corresponds to a 0/1/2 coding pattern. Reliability and validity studies have been conducted by Costello et al. A second instrument, the Child Behavior Checklist (CBCL), developed by Achenbach to provide a standardized format of descriptions of behavior was also used to tap parents' reports of their children's behavior (Goldman et ai., 1983). The CBCL takes about 20 minutes for parents to complete and consists of 118 behavioral items. A zero equals "not true," 1 equals "somewhat or sometimes true," and 2 equals "very true or often true" scale is used. The parents are asked to rate the child's behavior during the previous 6 months. Raw scores are converted into percentiles and into "T" scores. Profiles may be plotted as a function of the converted scores. The Child Behavioral Profile consists of three social competence scales as well as behavioral problem scales that were derived by factor analysis of checklists completed by parents of children referred to outpatient mental health services in 20 east coast mental health facilities (Achenbach and Edelbrook, 1983). The check list also gives a social competence score that reflects positive adaptive behaviors and abilities, and a total behavior problem score which reflects psychopathology. Several profiles have been devised for boys and/or girls, ages 4-5, 6 11, and years old. Test-retest reliability, and interrater agreement has been found to be highly significant (Achenbach and Edelbrook, 1983). Validity studies indicate that highly significant differences are found between clinic and normal children in the behavior problem scales. Clinical children also tend to score lower on social competence scales than normal children. Interviewers consisted of nine mental health professionals: six graduate students in psychology and three school counselors with M.A. degrees. Rater training in the use of DISC-P consisted of an introduction to the DSM-III diagnostic system, a lecture on the use of structured interviews with special reference to the DISC, and the videotaping of practice interviews. Each videotape was then rated by several other interviewers and group discussions were held for the purpose of resolving disparities in the ratings with frequent reference to the videotape record. The entire process encompassed approximately 6-8 hours of training for each interviewer. One graduate student in psychology initially sorted all of the parent interviews into two groups, one consisting of cases with minimal pathology and the other consisting of questionable cases. Two child psychiatrists reviewed the second group of cases using the diagnosis key manual supplied by Dr. Costello and independently arrived at one or more diagnoses based on strict application of the DSM-III criteria. Subsequently, the two psychiatrists reexamined the cases that produced discrepant diagnoses and then agreed on all diagnoses through discussions and repeated reference to the DSM-III and diagnosis key manuals. Results Interrater agreement for DISC-P, subjects' demographic characteristics, and prevalence of attention deficit and a variety of other DSM-III diagnoses in children are discussed in detail elsewhere (Shekim et al., 1985, 1986). In this report we will limit ourself to the comparison of the categorical diagnosis of ADDH as made by the DISC-P and the scores on the "hyperactive" factor of the Achenbach Child Behavior Checklist. Furthermore, a comparison will be made between ADDH children diagnosed by DISC-P and children with other DSM-III diagnoses on the narrow and wide band factors of Achenbach's scale. Fourteen children were given the diagnosis of ADDH according to the information provided by the parents interviewed with the DISC-P. These consisted of nine boys and five girls. Table 1 shows the comparisons between the T scores of all of the factors on Achenbach of the nine ADDH boys, the boys with no DSM-III diagnosis, as well as the boys with DSM-III diagnosis other than ADDH by DISC-P. It can be seen that the mean score on the hyperactive factor (factor 7) in ADDH boys as a group was significantly higher than the boys with other diagnoses and those boys with no diagnosis. Moreover, it is also noteworthy that the mean score on the hyperactive factor for the ADDH boys as a group was still within the normal range (using a T-score cut-off of 70 suggested by Achenbach). In fact only two of the boys categorically diagnosed as ADDH by the DISC-P scored above the T score of 70. The others would not have been considered "hyperactive" by solely using this measure. On the externalizing factors ofthe Achenbach scale, the DISC-P ADDH boys scored statistically significantly higher on the "hyperactive" and "aggressive" factors than both the boys with "no diagnosis" (ND) and the boys with "other DSM-III diagnoses" (OD) (Table 1). On the "delinquent" and "other problem" factors, the OD group fell in between the ADDH group and the ND groups. The ADDH boys did not differ from boys with other DMS-III diagnoses on the internalizing factors of the Achenbach scale. Both the ADDH boys and the boys with OD had statistically significantly higher scores on the depression and obsessive-compulsive factors. What is noteworthy in analyzing the internalizing

3 DIAGNOSIS OF ATIENTION DEFICIT DISORDER 655 TABLE 1 Achenbach's Factors T Scures in the Three Groups of Boys According to DISC-? (1) (2) (3) ADD No Diagnosis Other (N=9) (N= 18) Diagnosis Mean ± S,D. Mean ± S.D. Mean ± S.D. Schizoid or anxious NS 1 < 2 3 < 2" Depressed < < 2'" 3 < 2' Uncommunicative < < 2 3 < 2" Obsessive/Compulsive < < 2'" 3 < 2' Somatic complaints NS 1 < 2' Social withdrawal < < 2" 1 < 3" Hyperactive < < 2'" 1 < 3'" Aggressive < < 2'" 1 < 3'" Delinquent < < 2'" 1 < 3 Other problems < < 2'" 1 < 3' 3 < 2" Social competence l:l NS 1 < 3 Behavioral < < 2'" 1 < 3" 3 < 2'" Internalizing < < 2'" 3 < 2'" Externalizing < < 2'" 1 < 3'" 3 < 2" o p level of sifo:nificance on ANOVA. NS = not significant. '. ", are levels of significance on student t test two-tailed. <0.05 <0.025, <0.001, and 0.05 < p < 0.1. po factors is that the ADDH group scored as high as the OD group. What is also of interest is that the ADDH boys had statistically significantly higher scores on the "social withdrawal" scale than the other two groups. The variability on the Social Competence Scale was so large among the three groups that meaningful comparisons could not be made. On the other hand, the three groups had scores that were statistically significantly different from each other on the Behavioral Problems and Externalizing Scales with the ADDH group scoring highest, OD groups next, and the ND group coming lowest. Finally, the ADDH boys and the OD group had scores on the Internalizing Scale that were statistically significantly higher than the ND group. Table 2 presents the mean factor scores for the three groups of girls. The mean score on the "hyperactive" factor was statistically significantly higher for the girls with an ADDH diagnosis than it was for the girls with ND but not for the girls with OD. The mean score for the ADDH girls on the hyperactive factor was below 70 and none of the categorically diagnosed ADDH girls had a hyperactive factor score greater than 70. In contrast to the ADDH boys, very few of the other factor scores of the ADDH girls were statistically different from those factor scores for the other two groups of girls. When comparing the T scores of ADDH boys to ADDH girls on Achenbach's factors the boys scores were statistically higher than the girls on the aggressive factor; they tended to be more depressed and scored relatively higher on the social withdrawal and the internalizing scale. Overall, the ADDH boys were more aggressive, more depressed, more socially withdrawn and more internalizing than the ADDH girls (Table 3). Comparisons could not be made for the schizoid and the obsessive-compulsive factors since these factors are absent in girls profile. Figure 1 pictures the behavioral profiles of the 3 groups of boys on the Achenbach Child's Behavior Checklist. Discussion In general, six major types ofdiagnostic instruments are available for use in the diagnostic process with children: interview with the parents about the child; interviews and observations of the child; behavior rating scales completed by parents, teachers, and significant others in the child's life; physical examination; neurological examination; and laboratory studies. The making of a specific DSM-III diagnosis-that is, finding out what disorder or disorders the child presents with-is most likely done on the basis of the parental interview, the child interview, and the behavior rating scales. Very often in the United States single sources ofinformation, such as the teacher rating scale developed by Conners, have been used alone in making the diagnosis of "hyperactivity" (Conners, 1970). A particular cut-off score is recommended, and the children who score above that cut-off score are considered "hyperactive." Children who score below that are considered not hyperactive. However, this does not conform with the general way the diagnostic process in child psychiatry is done. The process usually involves collecting as much information from as many sources as possible, weighing the significance of the source of

4 656 SHEKIM ET AL. TABLE 2 Achenbach's Factors T Scores in the Three Groups of GirL~ According to DISC-P Add (N=;;) (mean ± s.n.) No Diagnosis (N = 24) (mean ± s.n.) Other Diagnosis (N = 1:~) (mean ± s.n.) Depressed ;,7 :~ ;;7 4 ;>8 6 0.:1 NS Social withdrawal IiR Ii 1i9 6 ;;9 ;; 0.07 NS Somatic complaints , O.:H NS Schizoid ohsessive 60 [j ;;8 4 1i6 2 2.:1;; NS 1>3 1> 2'" Sex prohlems I.,!)!).">9 7 1i NS Hyperactive 64 6 IiR 4 1i9 6 ;; 3.42 <0.05 Delinquent 62 [j NS Aggressiyp.">9 4.">7 :~."> NS Cruel ;,6 0 1i7 :1.">9."> 1.99 NS Ot.her prohlems 4 2 :\ 2 :~ NS Social competence IiO 6.">4 9."> :\ NS Behavioral.">7 Ii.">1 9."> NS Internalizi ng.">:1!).">:\ 7.">:\ II 0.03 NS Ext.ernalizing iii NS 1> 2' ". p level of significance on ANOVA. NS = not significant..... are levels of significance on st.udent. t t.est two-t.ailed. <0.05,... <0.00I, lind O.OIi < P < 0.1. F Ratio p _ TABLE :\ Achenbach's Fadors T Scores in the A[)[)H Hoys and Girls According to DISC-P ADDH Boys (N= 9) (mean ± s.il.) ADDH Girls (N=."» (mean ± S.Il.) Depressed li2 [j 57 :~ "> <p<o.l Social wit hdrawal "> :\.19 NS Somatic complaints 62 [j NS Hyperact ive (i NS Delinquent 6:\ [j 62 ;; 0.2;; NS Aggressive 67 7."> <0.0."> Ot her prohlems."> NS Social competence 4."> 10 ;; NS Behavioral 64 7."> "> NS Internalizing 61 7.">3 9 :U."> NS Externalizing (i _._ _ NS "p level of significance on ANOVA. NS = not significant. " "', are levels of significance on student t test two-tailed. <0.05, <0.001, and 0.0."> < P < 0.1. F Rat.io p. tnternaliz ING II III IV v VI EXTERNALIZ I NG VII VIII IX T SCORE c.. u ; ll _ ADDH Boy. DISC-P ~ Oth.r D.ogno DISC - P No Diogno". DISC-P B W <:> z '" "' -J "' :::E '"o z FI(;. 1. Children's profile on the Child Behavior Checklist..

5 DIAGNOSIS OF ATIENTION DEFICIT DISORDER 657 information, and making a diagnostic formulation of the child's problem. There are a few studies of this diagnostic process that look at the differential value of these various types of instruments in making specific diagnoses. In the classic Isle of Wight study by Rutter and his colleagues (Rutter et ai., 1970a, 1970b), an attempt was made to look at how much the parental interview by itself, the child interview by itself, the parent rating scale by itself, and the teacher rating scale by itself contribute to making a crude distinction between psychiatrically ill and psychiatrically well. In the Isle of Wight study, the parent interview alone, blind to other instruments, was used to make a diagnosis of psychiatrically ill versus psychiatrically well. The same was done with the child interview, the parent rating scale, and the teacher rating scale. Then one clinician, combining information from all sources, made the same distinction (psychiatrically ill versus psychiatrically well). When the individual instruments were examined to see how much they contributed to the making of that type of distinction (ill versus well), it was found that the parental interview was distinctly the best instrument when used alone. It was also found that the child interview by itself was probably the single least useful instrument-that is, there were very few children who were not found psychiatrically ill with other instruments that were thought to be so on the basis of the interview with the child alone. On the other hand, the interview with the child did tend to pick up certain types of disorder (such as minor depressive episodes) that the other instruments did not and also did help to make a distinction between types of disorder rather than the simple distinction of psychiatrically ill versus psychiatrically well. The data from the parent rating scale and the teacher rating scale were equally interesting. It was found that they were about equally effective in picking out children who were considered to be psychiatrically ill or psychiatrically well on the basis of all information combined. However, there was only a small positive overlap between the two. That is, the parent rating scale tended to pick up certain children. The teacher rating scale tended to pick up the other children. The implication is that some children have a disorder which is manifested primarily in school. Others have a disorder which is manifested primarily in the home. The nature of the ADDH syndrome makes it likely that ADDH children are more likely to show their disturbance or show it more severely in the school setting than they are in the home setting. This study would indicate that when the same source of information is used alone (that is, information from the parents) many more children would be diagnosed as having the ADDH syndrome by the use ofa systematic structured interview than would be considered to be "hyperactive" simply looking at cut-off scores on a systematic parent rating scale. In interviewing parents, symptoms can be further specified by asking for recent examples of behavior, the frequency of behavior, its severity, and the context of its occurrence. Circumstances which appear to precipitate certain aspects ofbehavior and those which ameliorate certain symptomatic problems can also be specified. Also, the age of onset and the chronicity of the disorder and degree of impairment can be discussed during the interview setting. The use of instruments such as the DISC-P has brought greater precision to the diagnostic process since these instruments improve the reliability of the collected data. The use of parent and teacher rating scales began in research settings, but they are becoming increasingly used in clinical practice as well. One can use the parent and teacher rating scales as simply data collection instruments. They can possibly add more precision to the diagnostic process if there are normative data available, and one can use cut-off scores to indicate that a particular symptom is statistically deviant or not. However, it should be recognized that statistical deviance does not always equal clinical significance. Moreover the use of the parent and teaching rating scales involves the assumption that the parents and teachers who are filling out these rating scales attribute the same meaning to each particular question that the originator of the scale meant. For example, an item such as "can't get my mind off of certain ideas, obsessions," generally means to a clinician true obsessional ideas. However, in exploring positive answers to these questions by parents and teachers, the meaning they attach to this question may be quite different. For example, parents may mean that when they take the child to a toy shop, he simply cannot get it out of his mind that he has to have a particular toy. Another problem with rating scales especially with those that have been factor analyzed is the labelling ofthe factors by the authors ofthe scales. For example, the ADDH boys in our sample scored higher on the obsessive-compulsive scale of Achenbach than the other two groups-a finding also reported by Barkley (1981a). However this finding can be misleading, since many questions on this scale ask about daydreaming, sleeping difficulties, and excessive talking, symptoms often present in the ADDH child, and are frequently endorsed as present by their parents. Barkley (l981b) reviewed a cross-section of 210

6 658 SHEKIM ET AL. scientific papers on hyperactivity conducted over a 20-year period. Barkley's review points out the rather miserable state of diagnosis of the ADDH syndrome in the previous literature. Only 36% of the studies reviewed by Barkley described specific symptoms of hyperactivity; 29% specified absence of neurological disorders or psychosis; 43% required an IQ greater than 70; 29% used parental complaints; 10% used standardized parent questionnaires; 13%, standardized teacher questionnaires and only 9% specified duration of symptoms. In many studies, only rating scale data were used with a cut-off score greater than 1.5 (or 2 standard deviations in the Conners parent or teaching rating scale or other instruments were used). The data from the Achenbach T scores in this study suggest that both the ADDH and "Other Diagnosis" boys score higher than the "No Diagnosis" group on the internalizing factors and the internalizing scale score. It further suggests that ADDH groups of boys score higher than both the other diagnoses and no diagnosis groups of boys on the externalizing factors and, surprisingly, the social withdrawal factor. On the other problem factor, the Behavioral scale score, and the Externalizing scale score, the T scores were on a continuum, with the ADDH group scoring the highest and the no diagnosis boys the lowest; the other diagnoses group of boys fell in between. What the Achenbach Factor T score reveals is that in our sample the ADDH boys were the most severely disturbed when compared with the children with other DSM-III diagnoses. The data from this study further suggest that while the ADDH children as a group had higher scores on the hyperactive factor on the CBCL than children with other diagnoses or children with no diagnoses, the group mean score for the ADDH boys and girls did not exceed the cut-off score suggested by Achenbach as being clinically significant. Moreover only two boys and none of the girls with an ADDH diagnosis exceeded this score. Had an integration of the data from a parent interview, a child interview, a teacher rating scale and a parent rating scale been used to make diagnoses in this population ofchildren, possibly a larger sample of children would have been given a categorical ADDH diagnosis. This would complicate the picture even more. This is the traditional process that one would use in clinical practice. It is unlikely that a single cut-off score on anyone particular rating scale, whether completed by parents or teachers, will be as good as or will substitute for a systematic clinical evaluation using standardized data collection instruments with proper synthesis of all the data collected. This should be kept in mind when reading recent reports of studies of ADDH children (Cantwell, 1984). References ACHENBACH, T. M. & E[)ELBROCK, C. S. (1983), ManlUll for the Revised Child Behavior Checkli.,t and Profile. Burlington, Vt.: University Associates in Psychiatry. BARKLEY, R.A. (1981a) Hyperactive Children: A Handbook for Diagnosis and Treatment. New York: Guilford Press. -- (1981b), Specific guidelines for defining hyperactivity in chil dren. In: Advances in Clinical Child Psychology, Vol. 14, ed. B. Lahey & A. Kazdin. New York: Plenum. CANTWELL, D. P. (Section Editor) (1984), Recent research on attention deficit disorder and related disorders. This Journal, 24: CONNERS, C. K. (1970), Symptom patterns in hyperkinetic, neurotic and normal children. Child Developm., 41: COSTELLO, A., EDELBROCK, C., KESSLER, M. & KALAS, R. (1982), Structured interviewing. A progress report on the NIMH diagnostic interview schedule for children (DISC). Presented at the Annual Meeting of the American Academy of Child Psychiatry (October) Washington, D.C. GOLDMAN, J., L'ENGLE STEIN C. & GUERRY, S. (1983), Psychological Methods of Child Assessment. New York: Brunner-Mazel, pp RUTTER, M., GRAHAM, P. & YULE, W. (1970a), A Neuropsychiatric Study in Childhood (Clinics in Developmental Medicine Nos ). London: Spastics International Medical Publicationsl Heinemann Medical Books. --TIZARD, J. & WHITMORE, K. (1970b), Education, Health and Behavior. London: Longmans. SHEKIM, W.O., KASHANI,,J., BECK, N., CANTWELL, D. P., MARTIN, J., ROSENBERG, J. & COSTELLO, A. (1985), The prevalence of attention deficit disorder in a rural midwestern community sample of nine-year-old children. This Journal, 24: MARTIN,.J., ROSENBERG. J. & COSTELLO, A. (1986), Prevalence of childhood psychiatric disorders in a community sample (submitted for publication).