Identifying non-affective psychosis in first admission patients: MMPI-2, structured diagnostic interview, and consensus lifetime best estimate
Introduction
The last decades have seen worldwide efforts and research targeting early detection of schizophrenia-spectrum psychosis. This effort was initiated in Australia (Yung et al., 2003) and was motivated by the recognition of the fact that many help-seeking individuals with subtle psychotic features failed to meet the full criteria for the schizophrenia diagnosis. We have elsewhere discussed in detail the high diagnostic threshold for schizophrenia in DSM-IV, DSM-5 and ICD-10 (Parnas, 2002, Parnas, 2012).
In the studies on early detection a variety of diagnostic approaches have been used, ranging from self-report measures to structured interviews. Kendler et al. (1996) observed in the US National Comorbidity Survey that the structured interview has limited utility in detecting psychosis. In our own study of 100 consecutive first admission patients, we found that a fully structured psychiatric interview, the Structured Clinical Interview for DSM-IV-TR or SCID, displayed high specificity but low sensitivity for schizophrenia and other non-affective psychotic disorders (Nordgaard et al., 2012). Other evidence has shown an overall low level of agreement between the SCID and clinicians’ diagnoses (Steiner et al., 1995).
We have consistently advocated for thorough psychiatric assessment by experienced clinicians as the “gold standard” for all schizophrenia-related diagnostic efforts (Leckman et al., 1982, Nordgaard et al., 2012) including early detection (Nordgaard et al., 2013, Parnas, 2015). Core criteria include the use of multiple sources of information such as historical records, psychological tests, informants’ observations, and following the patient over time (Meehl, 1959). We recognize the practical reality that in some clinic settings this gold standard may not be feasible, either due to a lack of economic resources or staff expertise. In this paper, we explore the possibility that using the MMPI-2 (Minnesota Multiphasic Personality Inventory-2) as an adjunct to the SCID can improve its diagnostic accuracy for schizophrenia-related psychosis at first admission. Since the MMPI-2 is a self-complete instrument that can be administered with limited staff time and training, its addition would not pose an undue burden on clinic resources.
One impediment to its use in early detection paradigms is that the MMPI-2 cannot be used “right off the shelf” to assign psychotic diagnoses like the SCID can. Although there is a traditional clinical practice of profile interpretation, where scale elevations above a standard cut point are sorted to identify characteristic 2- or 3-point code types, this practice has not yet produced a set of validated differential diagnosis decision rules using current diagnostic criteria.
Instead, the research literature has advanced several alternative approaches for identifying patients with schizophrenia1 among mixed psychiatric populations. One method is to use the Clinical scales, which reflect diagnostic categories in use at the time the MMPI was developed in the 1940s; the most consistent results for schizophrenia patients are a pattern of higher scores on Scale 8 (Schizophrenia) and lower scores on Scales 2 (Depression) and 7 (Psychasthenia) (Bagby et al., 2005, Ben-Porath et al., 1991, Graham, 2006, Greenblatt and Davis, 1999, Wetzler et al., 1998). Alternatively, the more recently constructed Content Scales (Butcher et al., 1990) may be used; here, the most consistent results for schizophrenia patients are a pattern of higher scores on the Bizarre Mentation (BIZ) scale and lower scores on the Depression (DEP) and Anxiety (ANX) scales (Bagby et al., 2005, Ben-Porath et al., 1991, Butcher et al., 1990, Graham, 2006, Munley et al., 1997, Wetzler et al., 1998). Another approach has been to construct an index using an arithmetic combination of several different scales. Goldberg developed an index using the original MMPI that outperformed expert clinicians in predicting psychotic vs. non-psychotic discharge diagnoses (Goldberg, 1965, Goldberg, 1968); an MMPI-2 update of the Goldberg Index was successful in discriminating schizophrenia from major depression (Egger et al., 2003). It is worthwhile to note that although Goldberg's Index made more efficient use of MMPI scale data than clinicians’ judgments, the gold-standard criterion that both attempted to predict was the discharge diagnosis assigned by the treating clinician.
Our overall aim in the current study is to test the ability of the above MMPI-2 measures to identify non-affective psychosis in a sample of first-admission psychiatric patients, and then to determine if the best-performing MMPI-2 measure can add to the diagnostic accuracy of the SCID alone.
Section snippets
Sample
The sample comprised consecutive first-admission patients at the Psychiatric Centre Hvidovre, a department of the University Hospital of Copenhagen. The department provides psychiatric service to a population of 150,000 in a catchment area of the City of Copenhagen as there are no private psychiatric in-patient facilities in Denmark. All consecutive first admissions from June 2009 to November 2010 were screened for eligibility. Due to ethical concerns, involuntarily admitted and legal patients
Results
Table 1 presents demographic and hospitalization information about the sample as a whole (N = 76), as well as by CLBE diagnostic group. The PSY (N = 33) and OMI (N = 43) groups did not differ from each other in terms of gender, age, marital status, education level, employment status prior to hospitalization, nor duration of hospitalization prior to the interview.
Among the LR tests of individual scales (presented in Table 2), only 3 were significant: Scales 7, 8, and BIZ. Examination of the
Discussion
The level of criterion validity demonstrated by the MMPI-2 in our study is roughly in line with the results from two important meta-analyses in the literature. One report looked at 31 studies that investigated any sort of relationship between MMPI scores and theoretically-related variables (such as between the MMPI Scale 2 (Depression) and the Beck Depression Inventory or between MMPI Scale 8 and days of psychiatric hospitalization). The overall average correspondence was r = 0.30, which the
Declarations of interest
None
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