Psychological Reports, 1991,69, 795-800. @ Psychological Reports 1991
LOW MMPI DIAGNOSTIC PERFORMANCE FOR THE DSM-111-R OBSESSIVE-COMPULSIVE PERSONALITY DISORDER ' CHRIS SCHOTTE, DIRK DE DONCKER, MICHAEL MAES, RAYMOND CLWDTS, AND PAUL COSYNS Antwerp Universi!y Hospital Summary.-This study investigated the diagnostic performance of the MMPI validity and clinical scales, and especially of Scale 7 (PA, for the DSM-111-R obsessivecompulsive personality disorder by comparing the MMPI variables for 24 obsessivecompulsive with those for 58 nonobsessive-compulsive inpatients. Both groups were diagnosed by semistructured interview (SCID-11). The obsessive-compulsive group obtained for the mean MMPI profile a 2-(6-1)(D-Po-Hs) code, with a tendency for a lowered Scale 4 (Pd) score, compared to the nonobsessive-compulsive group. Neither the ROC analysis of the individual MMPI scales, including Scale 7 (Pt), nor the analyses of frequency of two-point codes and elevated (T>69)scales showed any clear indications of good diagnostic performance for the DSM-111-R obsessive-compulsive personality disorder.
The MMPI, developed in the 1930s by Hathaway and McKinley, provides descriptions and predictions of patients based on the empirical correlates of the various codetypes. These descriptions and inferences can contribute in the psychodiagnostic assessment of the DSM-111-R personality disorders: several authors report on the MMPI characteristics of different personality disorders (e.g., Gartner, Hurt, & Gartner, 1989; Schotte, Maes, Cluydts, De Doncker, Claes, & Cosyns, 1991; Raskin & Novacek, 1989). The DSM-111-R (APA, 1987) concept of the obsessive-compulsive personality disorder reflects a tendency to be perfectionistic, behaviorally rigid, affectively constricted, overly disciplined, formalistic, intellectualizing, circumstantial, and detailed. Persons with obsessive-compulsive personality disorder tend to devote themselves to their work at the expense of family and friends, with whom they may be rather stiff, formal, domineering, and stubborn. They have difficulty enjoying their work and achieving their full potential because of their ruminative doubts, perfectionism, rigidity, and indecisiveness (Widiger & Frances, 1988). Scale 7 (Psychasthenia, Pt) of the MMPI is sometimes referred to as a measure of obsessive-compulsive traits (Kristianson, 1987): moderate elevations (60-69T) indicate obsessional personality aspects and suggest conscientious, perfectionistic, orderly, and selfcritical individuals who tend to worry over minor problems and are often described as religious, moralistic, worrisome, apprehensive, rigid, and metic-
'Address correspondence to C. Schotte, De artment of Psychiatry, Universitair Ziekenhuis Antwerpen, Wihijkstraat 10,2650 Edegem, ~ e L i u r n .
796
C. SCHOTTE. ETAL.
ulous (Lachar, 1974; Greene, 1980). High scorers are described as worried, tense, and indecisive; ag~tationmay develop and overt anxiety is usually apparent to both themselves and others. High elevations suggest agitated rumination, fearfulness, and the likelihood of fixed obsessions, compulsions, and phobias. Severe levels of anxiety may make even simple routine tasks impossible (Lachar, 1974; Greene, 1980). All 48 items of the original MMPI Scale 7 have been maintained in the MMPI-2 (Graham, 1990). The aim of the present, exploratory study was to investigate the MMPI characteristics of the DSM-111-R obsessive-compulsive personality disorder. METHOD The subjects were 82 inpatients admitted to the psychiatric ward of the University Hospital. Sampling was conducted over a 20-1110. period. The psychiatric ward of the University Hospital is a 30-bed short-term unit (with a mean length of stay of approximately 1 month), which specializes in the diagnosis and treatment of adult depressive and neurotic symptomatology. Most of the patients are from the Antwerp region and are referred by general practitioners and psychiatrists. The patients in this study showed no evidence of mental retardation and ranged between 17 and 64 years of age. The MMPI (566-item Dutch form) was individually administered to each patient two weeks after hospital admission. The inpatients were assessed with the Structured Clinical Interview for DSM-111-R (Spitzer & Williams, 1987), using the questionnaire and the sernistructured clinical interview, constructed for the diagnosis of the DSM-111-R personality disorders. Based on the results of the SCID-I1 interview, the sample was divided into 24 patients fulfilling the DSM-111-R criteria for obsessive-compulsive personality disorder and 58 patients obtaining a diagnosis of nonobsessive-compulsive (less than 5 DSM-111-R obsessive-compulsive criteria fulfilled) personality disorder. Differences between the group means on the K-corrected T scores of the MMPI scales were tested with the one-way analysis of variance. A receiver operating characteristics (ROC) analysis (Swets, 1979; Hsiao, Bartko, & Potter, 1989) was performed to estimate the discriminative power of the MMPI scales for the obsessive-compulsive diagnosis. A ROC analysis generates indices that describe all of a test's possible sensitivities and specificities. The ROC curve, which is a plot of the balance between sensitivity and specificity for a diagnostic test, is obtained by plotting the true-positive rate versus the false-positive rate for several cut-off values of a diagnostic test. The most widely used ROC index of accuracy which summarizes the discriminative power of a diagnostic system is the AUC index (Mossman & Somoza, 1989). The AUC index (area under the ROC curve) corresponds to the ~ r o b a b i l i tthat ~ a given MMPI scale will correctly sort a pair of subjects, one chosen randomly from the obsessive-compulsive and the other from the
797
MMPI: OBSESSIVE-COMPULSIVE PERSONALITY DISORDER
nonobsessive-compulsive sample. An AUC index of .5 indicates a performance no better than chance; an AUC index of 1.0 reflects a perfect diagnostic performance.
RESULTS No significant differences were obtained between the obsessive-compulsive and nonobsessive-compulsive groups on age (F,,80 = 1.34, p = .25; mean age for the total sample = 34.5 yr., SD = 11.8 yr.), or sex-ratio ( X , 2 = 3.44, p = .06). The female to male ratio in the total sample was 2.42:l; in the obsessive-compulsive group a 1.18:l and in the control group a 3.46:l ratio was observed. The mean number of SCID-I1 obsessive-compulsive criteria was significantly different (F,,,,= 145.21, p < suggesting that both diagnostic personality disorder groups are well differentiated with respect to the DSM111-R obsessive-compulsive features. Analysis of the prevalence of the SCID-I1 nonobsessive-compulsive diagnoses in both samples indicated only a significantly different prevalence rate in both groups for the borderline personality disorder diagnosis = 4.88, p = .03), which was more frequently diagnosed among the nonobsessive-compulsive sample. The distribution rates of the Axis I1 diagnoses in the total sample were 9.40% Cluster A diagnoses, 37.60% Cluster B diagnoses, 45.60% Cluster C diagnoses, and 7.40% NOS Axis I1 diagnoses. Concomitant clinical DSM-111-R Axis I diagnoses were obtained for each patient; no significant differences in the prevalence rates for the clinical syndromes were observed between both groups (maximal X , 2 = 2.40). The following diagnostic Axis I prevalence rates were observed in the total sample: 17% no Axis I diagnosis, 21.18% Adjustment Disorder, 21.18% Major Depression, 15.29% Substance Abuse Disorders, 12.94% Dysthymic Disorder, and 10.60% Somatoform Disorders. Table 1 displays the mean T scores of the MMPI scales and the summaries of the analysis of variance. No significant main effects for diagnostic TABLE 1
MEAN T SCORESOF MMPI SCALESAND ANALYSESOF VARIANCE MMPI Scales L F
K 1 Hs 2 D 3 HY
Personality Disorder Obsessive-Compulsive Nonobsessive-Compulsive M .FD M .TD 52.25 63.92 48.21 66.33 77.58 66.17
10.53 16.59 13.89 13.08 11.62 8.67
51.76 64.40 47.26 66.07 77.24 67.30
(continued on next page)
8.14 12.10 8.02 14.18 13.67 11.20
F
P
0.05 0.02 0.15 0.01 0.01 0.19
.82 .88 .70 .94 .91 .67
798
C. SCHOTTE, ET AL. TABLE 1 (CONT'D) MEANT SCORESOF MMPI SCALESAND ANALYSES OF VARIANCE
MMPI Scales
Personality Disorder Obsessive-Compulsive Nonobsessive-Compulsive M SD M SD
F
P
category, unless a tendency for a lower mean score on Scale 4 (Pd) in the obsessive-compulsive sample, were found. The mean profile of the obsessivecompulsive group obtained a 2-(6-1) code (D-Pa-Us), whereas the other personality disorder group obtained a 2-4-(6) code (D-Pd-Pa). The frequency distribution of the MMPI clinical scales elevated above a T score of 69, and of the clinical scales composing the two-point codes (two highest elevated scales) was calculated. No significant differences were observed between groups in the frequency of elevated clinical scales [maximal X,2 = .51, p = .48 obtained by Scale 4 (Pd)] or in the frequency of the clinical scales composing the two-point codes [maximal x , 2 = .977, p = .32 for Scale 4 (Pd)l. Table 2 presents the summary of the ROC analysis results. None of the MMPI scales obtained an AUC index over .65. Spearman correlations between the number of SCID-I1 obsessive-compulsive criteria and the MMPI T scores of the clinical and validity scales TABLE 2 SUMMARY OF THE ROC ANALYSES
MMPI Scales L
AM
S
.06 .04 .12 .02 .03 .10 .5 1 .14 .05 .02 .01 .23
1.29 1.37 1.73 .92 .85 .77 .98 1.17 .98 1.14 .82 .86
AUC Index
,483 F ,543 .470 K ,501 1 Hs ,498 2 D ,540 3 HY ,647 4 Pd ,542 6 Pa ,519 7 Pt ,506 8 Sc ,525 9 Ma ,565 0 Si Code: A M = di£ference in population means expressed in units of standard deviation of the nonobsessive population; S = ratio of the standard deviations of the two populations: S.,.,.,/S..,
MMPI: OBSESSIVE-COMPULSIVF, PERSONALITY DISORDER
799
were calculated: the largest correlation was 22, reflecting a weak association between the number of obsessive-compulsive traits and MMPI Scale 0 (Si). DISCUSSION The obsessive-compulsive personality disorder group in this study obtained for the mean MMPI profile a 2-(6-1) code (D-Pa-HI). The nonobsessive-compulsive personality disorder group obtained a 2-4-(6) code (D-Pd-Pa). Both groups were comparable with respect to the prevalence of the DSM111-R Axis I diagnoses. No significant differences were found between groups for the mean MMPI T scores of the validity and clinical scales. The higher Scale 4 (Pd) mean scores in the nonobsessive-compulsive group can be associated with the significantly higher prevalence of the borderline personality disorder dagnosis in t h s group. Indeed, Scale 4 (Pd) correlates positively with the number of SCID-I1 borderline criteria (Spearman rho = .45, t = 4.47, p < and negatively with the number of obsessive-compulsive criteria (Spearman rho = -.16; t = 1.45, p = .15). No significant differences were observed between groups in the frequency of elevated clinical scales or in the frequency of the clinical scales composing the two-point codes. The examination of the diagnostic performance of the individual MMPI scales for the obsessive-compulsive diagnosis by ROC analysis in the combined sample of inpatients indicated low parameters of diagnostic power. None of the MMPI scales obtained a significant AUC index; the highest AUC index was .647 for Scale 4 (Pd). A negative finding of this study is that Scale 7 (Pt) displays a low diagnostic ~erformancefor the assessment of the obsessive-compulsive personality disorder. Scale 7 (Pt) seems to constitute a general measure of classically neurotic concerns, preoccupations, and characteristics (Pollack, 1979) such as uncontrollable or obsessive thoughts, feelings of fear and anxiety, doubts, tension, unhappiness, physical complaints, and difficulties in concentrating rather than a measure of obsessive-compulsive personality traits. The results of this study indicate that the use of the classical MMPI validity and clinical scales as instruments for the diagnosis of the DSM-111-R obsessive-compulsive personality disorder in an inpatient sample is hampered by their low diagnostic performance. When using the MMPI as a diagnostic screening instrument, one could consider other sources of MMPI information such as the research and Wiggins content scales (Morey & Smith, 1988) or the MMPI Scales for DSM-I11 personality disorders, developed by Morey, Waugh, and Blashfield (1985). This set of personality disorder scales, specifically designed to assist in the assessment of the DSM-I11 personality disorders, obtained fairly high internal consistency estimates. The scales are the subject of validation studies by examination of the relationship between these scales and the traditional scales, of the interrelationshps between the
800
C. SCHOTTE, ET A L
scales, and by investigating the relationships with other diagnostic indicators of personality (Morey & Smith, 1988). Further research on larger populations of obsessive-compulsive patients could, because of the heterogeneity of Scale 7 (Pt), concentrate on the analysis of the Scale 7 (Pt) items, whose content is more directly related to the features of the obsessive-compulsive personality disorder. REFERENCES AMWCANPSYCHIATRICASSOCIATION. (1987) Dia nostic and statistical manual of mental disorders. (3rd ed., Rev.) Washington, DC: ~ u t f o r . GARTNER, J., HURT, S. W., & GARTNER,A. (1989) Psychological test s ~ g n sof borderline personality disorder: a review of the empirical literature. Journal o/ Personolio Assessment, 53, 423-441. GRAHAM,J. R. (1990) MMPI-2: assessing personality and psychopathology. New York: Oxford Univer. Press. GREENE,R. L. (1980) The MMPI: an interpretative manual. Orlando, FL: Grune & Stratton. HSIAO,J. K., BARTKO,J. J., & POTTER,W.Z. (1989) Diagnosing diagnoses: receiver operating characteristics methods and psychiatry. Archives of General Psychiatry, 46, 664-667. KRISTIANSON, I? (1987) A comparison between DSM-I11 descri tions and corresponding MMPI descriptions. Paper presented at the 10th Internationaf Conference on Personality Assessment, Brussels, Belgium. LACW, D. (1974) The MMPI: clinical assessment and automated interpretation. Los Angeles, CA: Western Psychological Services. MOREY,L. C., & SMITH, M. R. (1988) Personality disorders. In R. L. Greene (Ed.), The MMPI: use with specifc populations. Philadelphia, PA: Grune & Stratton. Pp. 110-158. MOREY,L. C., WAUGH,M. H., & BUSHFIELD,R. K. (1985) MMPI scales for DSM-I11 personality disorders, their derivation and correlates. Journal of Personality Arsessment, 49, 245-25 1. MOSSMAN, D., & SOMOZA,E. (1989) Assessing improvements in the dexamethasone suppression test using receiver operating characteristic analysis. Biological Psychiatry, 25, 159173. J. M. (1979) Obsessive-compulsive personality: a review. Psychological Bulktin, 86, POLLACK, 225-241. RASKIN,R., & NOVACEK, J. (1989) An MMPI description of the narcissistic personality. Journo1 of Personality Ajsesrrnent, 53, 66-80. S C H O ~C., , MAES, M., CLUYDTS,R., DE DONCKER, D., CMS, M., & COSYNS,P. (1991) MMPI characteristics of the DSM-111-R avoidant personality disorder. Psychological Reports, 69, 75-81. SPITZER,R. L., & WILLIAMS,J. B. (1987) Structured Clinical Interview for DSM-111-R personality disorders. Biometrics Research Department, New York State Psychiatric Institute, New York. SWETS,J. A. (1979) ROC analysis applied to the evaluation of medical imaging techniques. Investigative Radiology, 14, 109-121. W ~ I G E RT., A., & FRANCES, A. (1988) Penonality disorders. In J. Tdbott, R. Hales, & S. Yudofsky (Eds.), The American Psychiatric Press textbook of psychiaby. New York: American Psychiatric Press. Pp. 621-648. Accepted October 16, 1991.
LOW MMPI DIAGNOSTIC PERFORMANCE FOR THE DSM-111-R OBSESSIVE-COMPULSIVE PERSONALITY DISORDER ' CHRIS SCHOTTE, DIRK DE DONCKER, MICHAEL MAES, RAYMOND CLWDTS, AND PAUL COSYNS Antwerp Universi!y Hospital Summary.-This study investigated the diagnostic performance of the MMPI validity and clinical scales, and especially of Scale 7 (PA, for the DSM-111-R obsessivecompulsive personality disorder by comparing the MMPI variables for 24 obsessivecompulsive with those for 58 nonobsessive-compulsive inpatients. Both groups were diagnosed by semistructured interview (SCID-11). The obsessive-compulsive group obtained for the mean MMPI profile a 2-(6-1)(D-Po-Hs) code, with a tendency for a lowered Scale 4 (Pd) score, compared to the nonobsessive-compulsive group. Neither the ROC analysis of the individual MMPI scales, including Scale 7 (Pt), nor the analyses of frequency of two-point codes and elevated (T>69)scales showed any clear indications of good diagnostic performance for the DSM-111-R obsessive-compulsive personality disorder.
The MMPI, developed in the 1930s by Hathaway and McKinley, provides descriptions and predictions of patients based on the empirical correlates of the various codetypes. These descriptions and inferences can contribute in the psychodiagnostic assessment of the DSM-111-R personality disorders: several authors report on the MMPI characteristics of different personality disorders (e.g., Gartner, Hurt, & Gartner, 1989; Schotte, Maes, Cluydts, De Doncker, Claes, & Cosyns, 1991; Raskin & Novacek, 1989). The DSM-111-R (APA, 1987) concept of the obsessive-compulsive personality disorder reflects a tendency to be perfectionistic, behaviorally rigid, affectively constricted, overly disciplined, formalistic, intellectualizing, circumstantial, and detailed. Persons with obsessive-compulsive personality disorder tend to devote themselves to their work at the expense of family and friends, with whom they may be rather stiff, formal, domineering, and stubborn. They have difficulty enjoying their work and achieving their full potential because of their ruminative doubts, perfectionism, rigidity, and indecisiveness (Widiger & Frances, 1988). Scale 7 (Psychasthenia, Pt) of the MMPI is sometimes referred to as a measure of obsessive-compulsive traits (Kristianson, 1987): moderate elevations (60-69T) indicate obsessional personality aspects and suggest conscientious, perfectionistic, orderly, and selfcritical individuals who tend to worry over minor problems and are often described as religious, moralistic, worrisome, apprehensive, rigid, and metic-
'Address correspondence to C. Schotte, De artment of Psychiatry, Universitair Ziekenhuis Antwerpen, Wihijkstraat 10,2650 Edegem, ~ e L i u r n .
796
C. SCHOTTE. ETAL.
ulous (Lachar, 1974; Greene, 1980). High scorers are described as worried, tense, and indecisive; ag~tationmay develop and overt anxiety is usually apparent to both themselves and others. High elevations suggest agitated rumination, fearfulness, and the likelihood of fixed obsessions, compulsions, and phobias. Severe levels of anxiety may make even simple routine tasks impossible (Lachar, 1974; Greene, 1980). All 48 items of the original MMPI Scale 7 have been maintained in the MMPI-2 (Graham, 1990). The aim of the present, exploratory study was to investigate the MMPI characteristics of the DSM-111-R obsessive-compulsive personality disorder. METHOD The subjects were 82 inpatients admitted to the psychiatric ward of the University Hospital. Sampling was conducted over a 20-1110. period. The psychiatric ward of the University Hospital is a 30-bed short-term unit (with a mean length of stay of approximately 1 month), which specializes in the diagnosis and treatment of adult depressive and neurotic symptomatology. Most of the patients are from the Antwerp region and are referred by general practitioners and psychiatrists. The patients in this study showed no evidence of mental retardation and ranged between 17 and 64 years of age. The MMPI (566-item Dutch form) was individually administered to each patient two weeks after hospital admission. The inpatients were assessed with the Structured Clinical Interview for DSM-111-R (Spitzer & Williams, 1987), using the questionnaire and the sernistructured clinical interview, constructed for the diagnosis of the DSM-111-R personality disorders. Based on the results of the SCID-I1 interview, the sample was divided into 24 patients fulfilling the DSM-111-R criteria for obsessive-compulsive personality disorder and 58 patients obtaining a diagnosis of nonobsessive-compulsive (less than 5 DSM-111-R obsessive-compulsive criteria fulfilled) personality disorder. Differences between the group means on the K-corrected T scores of the MMPI scales were tested with the one-way analysis of variance. A receiver operating characteristics (ROC) analysis (Swets, 1979; Hsiao, Bartko, & Potter, 1989) was performed to estimate the discriminative power of the MMPI scales for the obsessive-compulsive diagnosis. A ROC analysis generates indices that describe all of a test's possible sensitivities and specificities. The ROC curve, which is a plot of the balance between sensitivity and specificity for a diagnostic test, is obtained by plotting the true-positive rate versus the false-positive rate for several cut-off values of a diagnostic test. The most widely used ROC index of accuracy which summarizes the discriminative power of a diagnostic system is the AUC index (Mossman & Somoza, 1989). The AUC index (area under the ROC curve) corresponds to the ~ r o b a b i l i tthat ~ a given MMPI scale will correctly sort a pair of subjects, one chosen randomly from the obsessive-compulsive and the other from the
797
MMPI: OBSESSIVE-COMPULSIVE PERSONALITY DISORDER
nonobsessive-compulsive sample. An AUC index of .5 indicates a performance no better than chance; an AUC index of 1.0 reflects a perfect diagnostic performance.
RESULTS No significant differences were obtained between the obsessive-compulsive and nonobsessive-compulsive groups on age (F,,80 = 1.34, p = .25; mean age for the total sample = 34.5 yr., SD = 11.8 yr.), or sex-ratio ( X , 2 = 3.44, p = .06). The female to male ratio in the total sample was 2.42:l; in the obsessive-compulsive group a 1.18:l and in the control group a 3.46:l ratio was observed. The mean number of SCID-I1 obsessive-compulsive criteria was significantly different (F,,,,= 145.21, p < suggesting that both diagnostic personality disorder groups are well differentiated with respect to the DSM111-R obsessive-compulsive features. Analysis of the prevalence of the SCID-I1 nonobsessive-compulsive diagnoses in both samples indicated only a significantly different prevalence rate in both groups for the borderline personality disorder diagnosis = 4.88, p = .03), which was more frequently diagnosed among the nonobsessive-compulsive sample. The distribution rates of the Axis I1 diagnoses in the total sample were 9.40% Cluster A diagnoses, 37.60% Cluster B diagnoses, 45.60% Cluster C diagnoses, and 7.40% NOS Axis I1 diagnoses. Concomitant clinical DSM-111-R Axis I diagnoses were obtained for each patient; no significant differences in the prevalence rates for the clinical syndromes were observed between both groups (maximal X , 2 = 2.40). The following diagnostic Axis I prevalence rates were observed in the total sample: 17% no Axis I diagnosis, 21.18% Adjustment Disorder, 21.18% Major Depression, 15.29% Substance Abuse Disorders, 12.94% Dysthymic Disorder, and 10.60% Somatoform Disorders. Table 1 displays the mean T scores of the MMPI scales and the summaries of the analysis of variance. No significant main effects for diagnostic TABLE 1
MEAN T SCORESOF MMPI SCALESAND ANALYSESOF VARIANCE MMPI Scales L F
K 1 Hs 2 D 3 HY
Personality Disorder Obsessive-Compulsive Nonobsessive-Compulsive M .FD M .TD 52.25 63.92 48.21 66.33 77.58 66.17
10.53 16.59 13.89 13.08 11.62 8.67
51.76 64.40 47.26 66.07 77.24 67.30
(continued on next page)
8.14 12.10 8.02 14.18 13.67 11.20
F
P
0.05 0.02 0.15 0.01 0.01 0.19
.82 .88 .70 .94 .91 .67
798
C. SCHOTTE, ET AL. TABLE 1 (CONT'D) MEANT SCORESOF MMPI SCALESAND ANALYSES OF VARIANCE
MMPI Scales
Personality Disorder Obsessive-Compulsive Nonobsessive-Compulsive M SD M SD
F
P
category, unless a tendency for a lower mean score on Scale 4 (Pd) in the obsessive-compulsive sample, were found. The mean profile of the obsessivecompulsive group obtained a 2-(6-1) code (D-Pa-Us), whereas the other personality disorder group obtained a 2-4-(6) code (D-Pd-Pa). The frequency distribution of the MMPI clinical scales elevated above a T score of 69, and of the clinical scales composing the two-point codes (two highest elevated scales) was calculated. No significant differences were observed between groups in the frequency of elevated clinical scales [maximal X,2 = .51, p = .48 obtained by Scale 4 (Pd)] or in the frequency of the clinical scales composing the two-point codes [maximal x , 2 = .977, p = .32 for Scale 4 (Pd)l. Table 2 presents the summary of the ROC analysis results. None of the MMPI scales obtained an AUC index over .65. Spearman correlations between the number of SCID-I1 obsessive-compulsive criteria and the MMPI T scores of the clinical and validity scales TABLE 2 SUMMARY OF THE ROC ANALYSES
MMPI Scales L
AM
S
.06 .04 .12 .02 .03 .10 .5 1 .14 .05 .02 .01 .23
1.29 1.37 1.73 .92 .85 .77 .98 1.17 .98 1.14 .82 .86
AUC Index
,483 F ,543 .470 K ,501 1 Hs ,498 2 D ,540 3 HY ,647 4 Pd ,542 6 Pa ,519 7 Pt ,506 8 Sc ,525 9 Ma ,565 0 Si Code: A M = di£ference in population means expressed in units of standard deviation of the nonobsessive population; S = ratio of the standard deviations of the two populations: S.,.,.,/S..,
MMPI: OBSESSIVE-COMPULSIVF, PERSONALITY DISORDER
799
were calculated: the largest correlation was 22, reflecting a weak association between the number of obsessive-compulsive traits and MMPI Scale 0 (Si). DISCUSSION The obsessive-compulsive personality disorder group in this study obtained for the mean MMPI profile a 2-(6-1) code (D-Pa-HI). The nonobsessive-compulsive personality disorder group obtained a 2-4-(6) code (D-Pd-Pa). Both groups were comparable with respect to the prevalence of the DSM111-R Axis I diagnoses. No significant differences were found between groups for the mean MMPI T scores of the validity and clinical scales. The higher Scale 4 (Pd) mean scores in the nonobsessive-compulsive group can be associated with the significantly higher prevalence of the borderline personality disorder dagnosis in t h s group. Indeed, Scale 4 (Pd) correlates positively with the number of SCID-I1 borderline criteria (Spearman rho = .45, t = 4.47, p < and negatively with the number of obsessive-compulsive criteria (Spearman rho = -.16; t = 1.45, p = .15). No significant differences were observed between groups in the frequency of elevated clinical scales or in the frequency of the clinical scales composing the two-point codes. The examination of the diagnostic performance of the individual MMPI scales for the obsessive-compulsive diagnosis by ROC analysis in the combined sample of inpatients indicated low parameters of diagnostic power. None of the MMPI scales obtained a significant AUC index; the highest AUC index was .647 for Scale 4 (Pd). A negative finding of this study is that Scale 7 (Pt) displays a low diagnostic ~erformancefor the assessment of the obsessive-compulsive personality disorder. Scale 7 (Pt) seems to constitute a general measure of classically neurotic concerns, preoccupations, and characteristics (Pollack, 1979) such as uncontrollable or obsessive thoughts, feelings of fear and anxiety, doubts, tension, unhappiness, physical complaints, and difficulties in concentrating rather than a measure of obsessive-compulsive personality traits. The results of this study indicate that the use of the classical MMPI validity and clinical scales as instruments for the diagnosis of the DSM-111-R obsessive-compulsive personality disorder in an inpatient sample is hampered by their low diagnostic performance. When using the MMPI as a diagnostic screening instrument, one could consider other sources of MMPI information such as the research and Wiggins content scales (Morey & Smith, 1988) or the MMPI Scales for DSM-I11 personality disorders, developed by Morey, Waugh, and Blashfield (1985). This set of personality disorder scales, specifically designed to assist in the assessment of the DSM-I11 personality disorders, obtained fairly high internal consistency estimates. The scales are the subject of validation studies by examination of the relationship between these scales and the traditional scales, of the interrelationshps between the
800
C. SCHOTTE, ET A L
scales, and by investigating the relationships with other diagnostic indicators of personality (Morey & Smith, 1988). Further research on larger populations of obsessive-compulsive patients could, because of the heterogeneity of Scale 7 (Pt), concentrate on the analysis of the Scale 7 (Pt) items, whose content is more directly related to the features of the obsessive-compulsive personality disorder. REFERENCES AMWCANPSYCHIATRICASSOCIATION. (1987) Dia nostic and statistical manual of mental disorders. (3rd ed., Rev.) Washington, DC: ~ u t f o r . GARTNER, J., HURT, S. W., & GARTNER,A. (1989) Psychological test s ~ g n sof borderline personality disorder: a review of the empirical literature. Journal o/ Personolio Assessment, 53, 423-441. GRAHAM,J. R. (1990) MMPI-2: assessing personality and psychopathology. New York: Oxford Univer. Press. GREENE,R. L. (1980) The MMPI: an interpretative manual. Orlando, FL: Grune & Stratton. HSIAO,J. K., BARTKO,J. J., & POTTER,W.Z. (1989) Diagnosing diagnoses: receiver operating characteristics methods and psychiatry. Archives of General Psychiatry, 46, 664-667. KRISTIANSON, I? (1987) A comparison between DSM-I11 descri tions and corresponding MMPI descriptions. Paper presented at the 10th Internationaf Conference on Personality Assessment, Brussels, Belgium. LACW, D. (1974) The MMPI: clinical assessment and automated interpretation. Los Angeles, CA: Western Psychological Services. MOREY,L. C., & SMITH, M. R. (1988) Personality disorders. In R. L. Greene (Ed.), The MMPI: use with specifc populations. Philadelphia, PA: Grune & Stratton. Pp. 110-158. MOREY,L. C., WAUGH,M. H., & BUSHFIELD,R. K. (1985) MMPI scales for DSM-I11 personality disorders, their derivation and correlates. Journal of Personality Arsessment, 49, 245-25 1. MOSSMAN, D., & SOMOZA,E. (1989) Assessing improvements in the dexamethasone suppression test using receiver operating characteristic analysis. Biological Psychiatry, 25, 159173. J. M. (1979) Obsessive-compulsive personality: a review. Psychological Bulktin, 86, POLLACK, 225-241. RASKIN,R., & NOVACEK, J. (1989) An MMPI description of the narcissistic personality. Journo1 of Personality Ajsesrrnent, 53, 66-80. S C H O ~C., , MAES, M., CLUYDTS,R., DE DONCKER, D., CMS, M., & COSYNS,P. (1991) MMPI characteristics of the DSM-111-R avoidant personality disorder. Psychological Reports, 69, 75-81. SPITZER,R. L., & WILLIAMS,J. B. (1987) Structured Clinical Interview for DSM-111-R personality disorders. Biometrics Research Department, New York State Psychiatric Institute, New York. SWETS,J. A. (1979) ROC analysis applied to the evaluation of medical imaging techniques. Investigative Radiology, 14, 109-121. W ~ I G E RT., A., & FRANCES, A. (1988) Penonality disorders. In J. Tdbott, R. Hales, & S. Yudofsky (Eds.), The American Psychiatric Press textbook of psychiaby. New York: American Psychiatric Press. Pp. 621-648. Accepted October 16, 1991.
