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.