The World Mental Health Composite International Diagnostic Interview
The World Mental Health Survey Initiative
World Health Organization Health and Work Performance Questionaire
CS-R Depression notes to all users:
The Depression section was modified extensively from the version used in the baseline NCS. Modifications were made by Kessler in consultation with Jules Angst, Kathleen Merikangas, and Hans-Ulrich Wittchen. This was done not only to update symptom requirements for DSM-IV, but also to build on knowledge we gained from the NCS clinical reappraisal studies. The latter showed that the UM-CIDI over-diagnosed Depression and that this occurred largely because the UM-CIDI designed too many respondents as having the very first symptoms of major depression -- two weeks of clinically significant dysphoria or anhedonia. Debriefing studies showed that this was true, in large part, for two reasons. First, the UM-CIDI bundled too much information into the diagnostic stem question about having symptoms most of the day nearly every day for two weeks or longer. Second, the UM-CIDI had no questions about the depth of dysphoria, leading to inclusion of clinically insignificant cases (e.g., a person who was sad about his baseball team losing the series, but not so sad that it met criteria for clinical significance). The NCS-R instrument tackled these problems by disaggregating the stem questions and adding questions about the clinical significance of the dysphoria. Note that the SC stem questions for Depression have a very low threshold, while the initial questions in the Depression section ask separately about length of the longest episode, for hours per days of symptoms, days per week of symptoms, and severity of dysphoria and anhedonia. Validity studies show that these modifications led to a substantial improvement in the concordance of the CIDI Depression diagnoses with blind clinical diagnoses.

The NCS-R Depression section, like all other diagnostic sections in the NCS-R, also adds expanded questions about age of onset using special probes developed in the baseline NCS and shown in methodological studies to improve reporting of age of onset1. Expanded questions are also included on lifetime course of illness, on persistence in the past 12 months, 12-month impairment, 12-month prevalence, and on history of service use for this disorder. While the logic of the questions about onset, course, 12-month persistence, 12-month severity, and service use is identical for all sections, the questions about 12-month prevalence are unique to each section. The general approach is to include questions from established disorder-specific clinical severity scales to validate reports of 12-month prevalence. In the case of Depression, the clinical scale selected was John Rush's Quick Inventory of Depressive Symptoms2 (Q-IDS). The Q-IDS was administered to all NCS-R respondents who were classified as 12-month cases of Depression in the CIDI. It should be noted that an error was found in the Q-IDS assessment in NCS-R that was corrected in subsequent WMH surveys: that three questions were omitted from the Q-IDS.

It is useful to make a brief comment here about the measures of 12-month disorder-specific impairment. As noted in the last paragraph, these questions were included in each diagnostic section of the NCS-R interview schedule. They consisted of the Sheehan Disability Scale (SDS)3 and a single question about the number of days in the past 365 days when the respondent was totally unable to carry out his or her daily activities as a result of the disorder. The SDS is a short scale that asks respondents to give 0-10 ratings of the amount of impairment caused by the focal disorder in each of four areas of role function home management, work, relationships with others, and social life. Although more extensive scales of role impairment are available, it was important for us to use a brief scale because we had to repeat the scale a number of different times for respondents who met criteria for a number of 12-month disorders. The SDS fit this bill nicely.

It is noteworthy, finally, that the final questions in the section on treatment both ask about age of first seeking help and about treatment in the past 12 months. It should be noted that the NCS-R contains a separate treatment section, which asks about treatment for "problems with emotions, nerves, or mental health" in the past 12 months. The comparison of responses to questions about disorder-specific 12-month treatment and questions about treatment for broadly defined emotional problems is used in the NCS-R and the other WMH surveys to evaluate absence of treatment for particular problems among people in treatment. This is especially important in the analysis of patients with comorbid mental and substance disorders, quite a few of whom receive treatment for one of these classes of disorders that ignores the other class of disorders.

The questions about age of onset of first contact, in comparison, are used in conjunction with questions about first onset of the disorder to study the typical duration of delays in seeking initial treatment.

Finally, a short series of questions is asked about how many patients ever felt that they received "adequate" treatment and, among those who did receive adequate treatment, the number of doctors they had to see before they received care that they considered adequate. Although the notion of treatment being "adequate" is subjectively defined, we believe that it is useful to know how many people who receive treatment for depression and other mental disorders believe that they have been helped and to correlate this belief with information in the NCS-R and WMH surveys about characteristics of the patient and of the treatment they received.

[1] Knäuper, B., Cannell, C.F., Schwarz, N., Bruce, M.L., & Kessler, R.C. (1999). Improving accuracy of major depression age-of-onset reports in the US National Comorbidity Survey. International Journal of Methods in Psychiatric Research, 8(1), 39-48.

[2] Rush, J., Carmody, T., Reimitz, P.-E. (2000) The Inventory of Depressive Symptomatology (IDS): Clinician (IDS-C) and Self-Report (IDS-SR) Ratings of Depressive Symptoms. International Journal of Methods in Psychiatric Research, 9, 45-59.

[3] Leon AC, Olfson M, Portera L, Farber L, Sheehan DV: Assessing psychiatric impairment in primary care with the Sheehan Disability Scale. Int J Psychiatry Med 1997. 27(2), 93-105.