Diagnostic assessment
As noted above, the IMHS was carried out as part of the WMH Survey Initiative 16.The disorders assessed include mood disorders (major depressive disorder, MDD; dysthymic disorder, bipolar I and II disorder, sub-threshold bipolar disorder), anxiety disorders (panic disorder, agoraphobia without a history of panic disorder, generalized anxiety disorder, GAD; specific phobia, social phobia, post-traumatic stress disorder, PTSD; obsessive-compulsive disorder, OCD), behavioral disorders (intermittent explosive disorder, attention-deficit/hyperactivity disorder), and substance-related disorders (alcohol abuse, alcohol dependence with abuse, drug abuse, drug dependence with abuse).All other 12-month cases were classified mild.As detailed elsewhere 18, blinded clinical reappraisal interviews with a probability sub-sample of CIDI respondents in a number of other WMH surveys found generally good concordance between diagnoses based on the CIDI and those based on the Structured Clinical Interview for DSM-IV (SCID) 19.Diagnoses in the IMHS, as in all other WMH surveys 17, are based on Version 3.0 of the WHO Composite International Diagnostic Interview (CIDI) 16, a fully-structured lay-administered interview that generates diagnoses according to the definitions and criteria of both the ICD-10 and DSM-IV diagnostic systems.The SDS assessed disability in work role performance, household maintenance, social life, and intimate relationships on 0-10 visual analogue scales with verbal descriptors, and associated scale scores, of none 0, mild 1, 3, moderate 4, 6, severe 7, 9, and very severe 10.Cases were classified serious if they had any of the following: a 12-month suicide attempt with serious lethality intent; substantial work limitations due to a mental or substance-related disorder; bipolar I disorder, substance dependence with a physiological dependence syndrome, a behavioral disorder associated with repeated serious violence, or any disorder that resulted in 30 or more days out of role in the year before interview.Cases not classified serious were classified moderate if they had any of the following: past year suicide gesture, plan, or ideation; 12-month substance dependence without serious role impairment; at least moderate work limitation due to a mental or substance-related disorder; or any 12-month disorder with at least moderate role impairment in two or more domains of the Sheehan Disability Scales (SDS, 22).This series began with questions designed to emphasize the importance of accurate response: "Can you remember your exact age the very first time (emphasis in original) when you (had the symptom/syndrome)?". Respondents who answered "no" were probed for a bound of uncertainty by moving up the age range incrementally (e.g., "Was it before you went to school?"; "Was it before age 13?", etc.).The CIDI assesses lifetime disorders and then obtains retrospective information about age-of-onset (AOO) and disorder recency.To assess the meaningfulness of these severity ratings, we compared number of days in the past 12 months that respondents reported being totally unable to carry out their normal daily activities because of mental or substance-related problems.Based on evidence that retrospective AOO reports are often erroneous 20, a special question sequence was used to improve accuracy of AOO reporting.Twelve-month cases were classified in terms of a three-category scheme of serious, moderate, or mild, based on additional information collected in the interviews.Experimental research has shown that this question sequence yields more plausible responses than standard age-of-onset questions 21.The mean (+- standard error) of this variable was significantly higher (F2,4,329 = 77.2, p0.001) among respondents classified serious (59.9+-14.6) than moderate (9.3+-1.7) or mild (7.0+-3.1)Diagnostic hierarchy rules and organic exclusion rules were used in making all diagnoses.Logistical complexities made it impossible to carry out a clinical reappraisal study in the IMHS.Onset was set at the upper end of the bound of uncertainty (e.g., age 12 years for respondents who reported that onset was before the beginning of their teens).DSM-IV criteria are used here.