Instruments to Identify Cases
The calculations defined in the preceding assume a fundamental requirement of epidemiological research, the ability to define a case. Historically, defining “caseness” in psychiatric epidemio-logic studies has been difficult. The development of structured diagnostic interview schedules tailored to clear operationalized diagnostic criteria has been the crucial element underlying the recent progress in psychiatric epidemiology.
The feasibility and benefits of structured, or semistruc-tured, interview schedules that could systematically elicit crite-ria for objectively defined disorders further became evident after the appearance and widespread use of instruments such as the Schedule for Affective Disorders and Schizophrenia (SADS) (Endicott and Spitzer, 1978), the companion interview for the Research Diagnostic Criteria (Spitzer et al., 1978). The SADS and the Research Diagnostic Criteria were originally developed for use by psychiatrists in the multisite collaborative study of the psychobiology of depression sponsored by the NIMH (Katz et al., 1979). Other standardized psychiatric interviews that have been commonly used are the present state examination (Wing et al., 1974) and its successor, the schedule for clinical assessment in neuropsychiatry (Wing et al., 1990); the structured clinical in-terview for DSM-III-R (Spitzer et al., 1992); and the diagnostic interview for genetic studies developed by the NIMH-sponsored centers for genetic linkage research (Nurnberger et al., 1994). Puig-Antich and colleagues have also developed an instrument for use with children, the Kiddie-SADS, that has been modified for epidemiological studies (Orvaschel, 1985).
The first widely used of a new family of instruments is the Diagnostic Interview Schedule (Robins et al., 1981). The Diag-nostic Interview Schedule was originally designed for the five-site epidemiological catchment area (ECA) study of DSM-III disorders (Regier et al., 1984). The ECA methodology and findings are de-scribed in more detail later. Subsequent versions of the Diagnostic Interview Schedule incorporated revised DSM-III (DSM-III-R) as well as Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. In the field of children’s men-tal health, fully structured diagnostic interview schedules have also been designed, such as the Diagnostic Interview Schedule for children (Costello et al. 1988; Jensen et al., 1995).
Another fully structured instrument is the composite in-ternational diagnostic interview (CIDI), developed in collabora-tion with the World Health Organization (WHO 1990) and NIMH (Wittchen et al., 1991). The CIDI was designed to be used with both DSM and ICD diagnostic criteria and to be available in mul-tiple languages.