Diagnostic accuracy and confusability analyses: an application to the Diagnostic Interview for Genetic Studies.
The dominant, contemporary paradigm for developing and refining diagnoses relies heavily on assessing reliability with kappa coefficients and virtually ignores a core component of psychometric practice: the theory of latent structures. This article describes a psychometric approach to psychiatric nosology that emphasizes the diagnostic accuracy and confusability of diagnostic categories. We apply these methods to the Diagnostic Interview for Genetic Studies (DIGS), a structured psychiatric interview designed by the NIMH Genetics Initiative for genetic studies of schizophrenia and bipolar disorder. Our results show that sensitivity and specificity were excellent for both DSM-III-R and RDC diagnoses of major depression, bipolar disorder, and schizophrenia. In contrast, diagnostic accuracy was substantially lower for subtypes of schizoaffective disorder-especially for the DSM-III-R definitions. Both the bipolar and depressed subtypes of DSM-III-R schizoaffective disorder had excellent specificity but poor sensitivity. The RDC definitions also had excellent specificity but were more sensitive than the DSM-III-R schizoaffective diagnoses. The source of low sensitivity for schizoaffective subtypes differed for the two diagnostic systems. For RDC criteria, the schizoaffective subtypes were frequently confused with one another; they were less frequently confused with other diagnoses. In contrast, the DSM-III-R subtypes were often confused with schizophrenia, but not with each other.
Faraone
S V
SV
Harvard Institute of Psychiatric Epidemiology and Genetics, Harvard Medical School Department of Psychiatry, Boston, USA.
Blehar
M
M
Pepple
J
J
Moldin
S O
SO
Norton
J
J
Nurnberger
J I
JI
Malaspina
D
D
Kaufmann
C A
CA
Reich
T
T
Cloninger
C R
CR
DePaulo
J R
JR
Berg
K
K
Gershon
E S
ES
Kirch
D G
DG
Tsuang
M T
MT
D001714:Bipolar Disorder / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D006801:Humans; D010552:Personality Assessment / Q000706:statistics & numerical data*; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011594:Psychometrics; D011618:Psychotic Disorders / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D015203:Reproducibility of Results; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology