Respondents were classified as having lifetime BP-I if they ever had a manic episode, defined by a period of seven days or more with elevated mood plus three other mania-related symptoms, or irritable mood plus four other mania-related symptoms, with the mood disturbance resulting in marked impairment, need for hospitalization, or psychotic features. Respondents were classified as having lifetime BP-II if they had both MDE and a hypomanic episode, defined by a period of four days or more with symptom criteria similar to mania and with an unequivocal change in functioning, but without a manic episode. Criteria for subthreshold hypomania included the presence of at least one of the screening questions for mania and failure to meet the full diagnostic criteria for hypomania. In the remainder of this report, we use the abbreviation “BPD to refer to people with either BP-I or BP-II, and “BPS” to refer to bipolar spectrum comprised of either BP-I, BP-II or subthreshold BP. The DSM-IV requirement that symptoms do not meet criteria for a Mixed Episode was not operationalized in making these diagnoses.
Among respondents with lifetime BP-I or BP-II, those reporting an MDE or a manic/hypomanic episode at any time in the 12 months before the interview were classified as having 12-month BPD. The number of manic/hypomanic episodes and MDE in this 12-month period was assessed. For those having episodes in the past 12 months, symptom severity and role impairment were also assessed. Symptom severity for the most severe month in the past 12 months was assessed with the self-report versions of the Young Mania Rating Scale (YMRS)22 (link), 23 (link) for mania/hypomania and the Quick Inventory of Depressive Symptoms (QIDS)24 (link) for MDE. We defined level of severity for manic/hypomanic episode and MDE as severe (YMRS> 24, QIDS > 15), moderate (14 25 (link). Respondents were asked to focus on the months in the past year when their manic/hypomanic episode or MDE was most severe and to rate how much the condition interfered with their home management, work, social life, and close relationships using a visual analogue scale from 1 to 10. Impairment was scored as none (0), mild (1–3), moderate (4–6), severe (7–9), or very severe (10). Clinical features such as age of onset, course, longest lifetime episode, and number of months in episode during previous year were assessed separately for manic/hypomanic episodes and MDE.