1. Historical Overview of the WHO CIDI

The World Health Organization (WHO) first developed the CIDI in 1990 (http://www3.who.int/cidi/). The CIDI (CIDI V2.1) was an expansion of the Diagnostic Interview Schedule developed by Lee Robins et. al with the support from the National Institute of Health (DIS; Robins, Helzer, Croughan and Ratcliff, 1981). The CIDI addressed the problem that the DIS diagnoses are exclusively based on the definitions and criteria of the Diagnostic and Statistical Manual (DSM) of Mental Disorders, while the international standard diagnostic system used is the WHO International Classification of Disease (ICD). Therefore, by including the ICD it was possible to do cross-national comparative research. WHO created the International Consortium in Psychiatric Epidemiology (ICPE) in 1997 (http://www.hcp.med.harvard.edu/icpe/) to compare results from a dozen countries that translated and field-tested the CIDI when it first became available. They determined that this first generation of CIDI surveys was hampered by the fact that the comparability across countries was limited to the assessment of mental disorders. Measures of risk factors, consequences, patterns and correlates of treatment were not included in the WHO CIDI. As a result, the ICPE launched an initiative to coordinate these measures. The WHO World Mental Health (WMH) Survey Initiative was created in 1998 (http://www.hcp.med.harvard.edu/wmh/). Scientists from participating countries from around the world came together to create measurements for risk factors, consequences, treatment, etc. and, in addition, the diagnostic sections of the CIDI were expanded to make it more operational. Thus, the WHO CIDI was born.

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a. Distress and Impairment - Questions about distress and impairment have been added to each diagnostic section in an effort to improve the operationalization of the DSM-IV requirement that clinically significant distress or impairment must be present for a symptom cluster to qualify as a DSM disorder. The focus of these questions is on lifetime prevalence.

b. Clinical Severity - Respondents who meet WHO CIDI criteria for a lifetime diagnosis and who report recency within the past 12 months are administered a new series of questions regarding the 12-month severity of their disorder. These questions include the Sheehan Disability Scales (SDS), which are administered in each diagnostic section, and disorder specific clinical severity scales. Comparison of SDS scores across diagnoses will allow us to compare the severity distributions of different disorders.

c. Course - We expanded the standard CIDI assessment in each diagnostic section to add questions about the persistence of the course of the disorder. Included here are both questions about lifetime course (e.g., number of episodes, number of years with at least one episode) and questions about 12-month persistence (e.g., number of weeks out of 52 in the past 12 months with symptoms). The course questions differ somewhat across disorders in recognition of the fact that some disorders are episodic (e.g., depression, mania, nonaffective psychosis), while others consist of clusters of attacks (e.g., panic disorder, intermittent explosive disorder), and still others are more typically conceptualized as being defined in terms of fairly persistent dispositions (e.g., phobias).

d. Subthreshold Assessment - The skip logic in CIDI 2.1 has been revised to collect information on subthreshold diagnoses. For example, both minor depression and recurrent brief depression are assessed along with major depression. Our thinking here is that the information collected in WHO CIDI on impairments and adverse consequences of mental disorders can be used as external standards against which to evaluate the clinical significance of diagnostic threshold rules.

e. Noncore Disorders - The core diagnoses in WHO CIDI are the anxiety disorders, mood disorders, substance use disorders, and personality disorders. These disorders are agreed worldwide to be of considerable importance. However, we also have interest in a number of other disorders that may or may not prove to be important and that we have designated noncore disorders. The noncore disorders include PTSD, Neurasthenia, Tobacco, Eating Disorder, Premenstrual Dysphoric Disorder, Obsessive-Compulsive Disorder, Psychosis, Gambling, Attention Deficit Disorder and Hyperactivity, Oppositional Defiant Disorder, Conduct Disorder, and Separation Anxiety.

f. Disorders with a Special Focus - WHO CIDI includes in the core a number of disorder-specific in-depth assessments that are designed to expand our knowledge of the overall structure of psychopathology as well as of our knowledge regarding subtypes of particular disorders. Several diagnoses warrant mention in this regard here:

i. Depression - An expanded series of symptom questions is included in this section to create a subtype of people who become irritable during their depressive episodes as well as people with mixed episodes that include reverse vegetative symptoms in the manic spectrum.

ii. Panic: The WHO CIDI assessment of panic includes a newly developed series of questions designed to clarify the distinction between people whose panic attacks occur exclusively in phobic situations, those whose attacks sometimes occur "out of the blue," and a third type of respondent who has attacks of both types.

iii. Agoraphobia: In a similar way, the WHO CIDI assessment of agoraphobia includes a newly developed series of questions to distinguish a true subtype of agoraphobia without panic from people who in previous surveys were incorrectly diagnosed as agoraphobic when they actually had adult separation anxiety or specific phobia.

iv. Specific Phobia: The WHO CIDI assessment of specific phobia includes a new series of probe questions separately dating onset of fear and avoidance of a range of specific phobia subtypes. In addition, new clarifying questions are asked to distinguish subtypes triggered by mini-traumas (e.g., animal phobia among children who were attacked by an animal) versus those that occurred out of the blue. We also ask new questions to improve the accuracy of subtyping by assessing the foci of the specific fear. For example, we collect information from people with fear of flying regarding whether the fear is of heights, of closed spaces, of crashing, of being unable to escape in the event of a panic attack, some other focus, or some combination of multiple foci.

v. Intermittent Explosive Disorder: IED has not previously been included in CIDI surveys. Given the enormous public health importance of interpersonal violence, we decided that this diagnosis should be included in WHO CIDI. A new CIDI module for IED was consequently developed in collaboration with the core members of the DSM-V task force on IED. Given that WHO CIDI will be the first large-scale epidemiological survey to assess IED, a number of special subtyping questions have been included that will doubtlessly prove of great importance in refining the diagnostic criteria for this disorder.

vi. PTSD: The WHO CIDI section of PTSD has been greatly expanded in comparison to the standard CIDI in several ways. First, we now know that traumas are important predictors of a great many other disorders than PTSD. As a result, we have now collected comprehensive data on lifetime trauma exposure, including information on age of first exposure to each qualifying trauma. This information can be used in risk factor analysis to study the effects of traumas on a broad range of other disorders. Secondly, recent research has made it very clear that PTSD is a much more commonly occurring and seriously impairing disorder than previously believed to be the case. As a result, it is of importance to carry out a thorough evaluation of this disorder in WHO CIDI. We do this by expanding the question series to include information on duration and severity of symptoms in each of the main PTSD symptom clusters. In addition, we assess up to three episodes of PTSD for each respondent, including the worst lifetime episode, a randomly selected episode, and an episode in the past 12 months. Information on the worst lifetime episode is needed to generate lifetime diagnoses. However, this will not tell us about conditional risk of PTSD given trauma exposure or interactions between age and prior disorders in affecting risk of PTSD after trauma exposure. It is necessary to assess PTSD for a random sample of traumas to obtain information on these conditional risks. We do this by enumerating all traumas experienced by each respondent, assessing PTSD for the self-defined worst trauma, and then randomly selecting one trauma for additional assessment in the subsample of respondents who meet criteria for PTSD associated with the worst trauma and who report the lifetime occurrence of two or more traumas. In cases where the randomly selected trauma and the worst trauma are different in this subsample, we carry out a complete PTSD symptom assessment a second time focused on the random trauma. In addition, respondents who meet lifetime criteria for PTSD are administered a new series of questions about symptom frequency in the 12 months prior to the interview. Questions of this sort have never before been included in CIDI surveys, making it previously impossible to obtain an unbiased estimate of the current prevalence of PTSD.

g. The Screening Section - The very first section in the WHO CIDI interview is the Screening Section. This is section includes a series of introductory questions about the respondent's general health which is followed by the diagnostic stem questions for the primary disorders assessed in the survey. Methodological research has shown that separating the stem questions from the probe questions in this way dramatically increases the accuracy of diagnostic assessments by reducing the effects of respondent fatigue and unwillingness to disclose on stem question endorsement. Some of the other noncore disorders are screened at the beginning of the individual section. All respondents of the CIDI (either PAPI or CAPI) must complete the entire screening section, regardless of the diagnostic sections that you have decided to administer for your study. This allows comparison across samples and surveys that differ in the exact diagnoses assessed.

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a. Chronic Conditions - This section administers a standard physical chronic conditions checklist that obtains information on the prevalence, age of onset, and recency of a wide range of commonly occurring physical (e.g., cancer, heart disease) and potentially psychophysiological (e.g., irritable bowel syndrome, chronic fatigue syndrome) disorders. An important aspect of the chronic conditions section is that the Sheehan Disability Scales, the same scales used to assess the role impairments due to separate mental disorders, will be administered to one randomly selected physical disorder for each respondent. This will make it possible to carry out direct comparisons of the impairments caused by mental disorders and physical disorders.

b. The WHO Disability Assessment Schedule (WHO-DAS) - The WHO-DAS is a recently developed instrument designed to operationalize the criteria of the revised International Classification of Impairments, Disabilities, and Handicaps. Referred to in the instrument as "30-Day Functioning", WHO-DAS assesses these criteria for the past 30 days and without regard to specific causal conditions. Specifically, WHO-DAS asks respondents to report on the extent to which all their health problems together have had effects of various sorts on their functioning in the past 30 days. All WHO CIDI respondents will be asked the WHO-DAS questions whether or not they report health problems. The WHO-DAS assessments will be treated as a series of outcome variables in multivariate analyses aimed at evaluating the relative effects of different mental and physical disorders on role functioning and the nonadditive effects of commonly occurring comorbidities among disorders on role functioning.

c. Services - WHO CIDI has two different types of service assessments. The first is a disorder-specific assessment that asks a short series of questions about lifetime and recent treatment of each CIDI disorder in each diagnostic section of the interview. The second is a global assessment that asks a much more substantial series of questions that focus largely on service use in the 12 months prior to the interview. The standard CIDI does not include a services section of either type. This has dramatically reduced the policy significance of previous CIDI surveys. The inclusion of a detailed services section in WHO CIDI is designed to correct this situation.

d. Childhood - In keeping with the interest in the effects of traumatic life experiences on mental illness, WHO CIDI includes a fairly detailed retrospective assessment of childhood experiences. Data are collected on childhood adversities of a wide variety of sorts as well as on parental bonding and parental mental disorders. The purpose here is to expand the assessment of exposure to stress in order to provide all the information needed to carry out a detailed study of the effects of stress on the onset and course of mental disorders.

e. Expanded Demographic Sections - WHO CIDI includes a series of separate sections on marriage, work, children, and finances in addition to a separate section on demographics. This expanded series of assessments of sociodemographic variables is designed to provide life course information that can be used both to study risk factors for mental disorders and to study adverse social consequences of mental disorders. Family Burden is an example of a section added to measure adverse social consequences. However, for the paper and pencil version (PAPI) of the WHO CIDI this section is asked of only 30% of the subjects in the long form (see New Sampling Conventions for the Paper and Pencil Version (PAPI) below for more information regarding the PAPI long form).

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CAPI Modularization - The CAPI Modularization program is the entrance point into the WHO CIDI CAPI instrument, allowing the selection of sections to administer in an interview. This is accomplished by offering a user-friendly interface for adding or removing sections as well as randomizing the proportion of respondents who receive a section, which in turn drives the instrument's routing behind-the-scenes in the WHO CIDI CAPI instrument. Therefore, the modularization program eliminates the need for a computer programmer to make such modifications. So for example, if a researcher is only interested in administering Depression and Mania, he/she will mark only these sections. In addition, the researcher may choose the % of subjects that will randomly enter these sections. To reduce interview length, a researcher may decide that in addition to Depression and Mania he/she will ask only 50% of the subjects the PTSD section. To do this, the Mania and Depression sections would be marked in the interface with 100% selection and the PTSD section would be marked with the percentage box set to 50%, meaning that 100% of the population that endorses the Mania or Depression screening question will go into those sections, but 50% of the total population will go into the PTSD section (there is no screener for PTSD).

PAPI Modularization - Modularization for the paper and pencil version of the CIDI is also possible. You may select the diagnostic sections that are entered for the short form (or Part I of the interview) other than the screening section which all respondents must complete and you may select the diagnostic sections that are entered for the long form (or part II of the interview). Or, if you prefer not to do a long/short interview, you may select which diagnoses out of the entire set you are interested in studying and set the percentages that receive each section in the front-end PAPI Modularization interface. If you choose this option, you must handle the randomization at the end of each section to go into the next section, and you must enter these data in a separate data entry program (you will not be able to enter this into the DDE we provide). Further details and examples will be given in the WHO CIDI training. See a further explanation of the long/short form below in New Sampling Conventions for the Paper and Pencil Version (PAPI).

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The Long Form and Short Form - The rationale for making a long versus short distinction revolves around the optimal allocation of resources. It is more expensive to carry out a long interview than a short interview, which means that the number of interviews that can be completed for a fixed budget will be greater if the interview is shorter. It is necessary for the interview to be long for respondents who meet criteria for mental disorders, as we need to ask these people a great many symptom questions, as well as questions about service use, risk factors, and impairments. It is also important to collect data on services, risk factors, and impairments from some people who do not have mental disorders as a baseline for comparison on these variables. However, given that only a fairly small minority of people in the general population meet criteria for any one mental disorder, it is not necessary to collect comparison data on all controls in the general population. Controls can be subsampled. This leads to a substantial reduction in the average length of the interview and, thereby, reduces study costs. The paper and pencil instrument is designed to have an average interview length of two hours in the subsample of respondents who receive the long form and 45 minutes in the subsample who receive the short form. The long form is administered to 100% of respondents who score in the positive range for any of a subset of the core diagnoses plus a random subsampleof other respondents. The proportion of others to select depends on considerations of statistical power based on prior assumptions about likely prevalence using the logic of a retrospective case-control design. We have chosen a 25% subsample. However, you may change this percentage. The standard selection strategy makes use of pre-assigned interview ID numbers. Note that the last two digits of these numbers have to be assigned randomly for this approach to work.

Deleting the Long/Short Form Interviewer Checkpoint (L/S2) - Another option is to remove the Long/short distinction altogether,in which case you would select the diagnoses you are interested in and you may choose the percentage of respondents that enter them. For example, you may choose to have 100% of your respondents be screened for Depression and Mania, but only a random 50% of respondents will be screened for PTSD. If you choose to set up your study in this manner, you must handle the randomization yourself and you will have to data-enter this information independent from the DDE that we provide. See PAPI Modularization above for more information.

The Sampling Grid - We select one random trauma in the PTSD section and one random chronic condition in the chronic conditions section for detailed assessment. A somewhat more complex randomization scheme is needed here due to the fact that the number of traumas and the number of chronic conditions reported to have occurred wil vary from one respondent to another. This is done automatically in the computer assisted version of the WHO CIDI (CAPI). It has to be done manually, in comparison, in the PAPI version. This is accomplished using a sampling grid. The details of how to use the sampling grid are described in the interviewer training materials for paper and pencil administration. The implementation of the selection procedure is again based on a random number scheme.

The Reference Card - The complexity of the WHO CIDI PAPI version requires that the interviewer frequently make reference to answers given earlier in the interview in order to determine the appropriate logical skips for the individual respondent. We have found on the basis of past experience that the job of the interviewer is made considerably easier if we avoid turning back many pages by recording critical information on a special reference card at the time the information is collected. When necessary, the interviewer can then refer to that card in making skip decisions. As with the sample grid, the reference card is explained in detail in the training materials and thoroughly covered in interviewer training.

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For an in-depth analysis of the methodological issues involved in designing the WHO CIDI please see Full Text of Kessler R.C., Ustun, T.B. (2004). The World Mental Health (WMH) Survey Initiative version of the World Health Organization (WHO) Composite International Diagnostic Interview (CIDI). The International Journal of Methods in Psychiatric Research, 13(2), 93-121.

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WHO CIDI Diagnostic Algorithms
Disorder	WHO CIDI Required Sections

Mood DSM IV Major Depressive Disorder Depression, Mania DSM IV Major Depressive Episode Depression ICD Severe Depressive Episode Depression, Mania ICD Moderate Depressive Episode Depression, Mania DSM IV Minor Depressive Disorder Depression, Mania ICD Mild Depressive Episode Depression, Mania DSM IV Recurrent Brief Depression Depression, Mania DSM IV Dysthymia Depression, Mania ICD Dysthymia Depression, Mania DSM IV Hypomanic Episode Mania ICD Hypomania Mania DSM IV Manic Episode Mania ICD Mania Mania Anxiety DSM IV Agoraphobia Agoraphobia, Separation Anxiety DSM IV Agoraphobia w/out Panic Agoraphobia, Separation Anxiety, Panic Disorder ICD Agoraphobia with, w/out Panic Agoraphobia DSM IV GAD GAD, Depression, Mania ICD GAD GAD, Panic Disorder, Social Phobia, OCD DSM IV OCD OCD ICD OCD OCD DSM IV Panic Attack Panic Disorder ICD Panic Attack Panic Disorder DSM IV Panic Disorder Panic Disorder ICD Panic Disorder Panic Disorder DSM IV Social Phobia Social Phobia ICD Social Phobia Social Phobia DSM IV Specific Phobia Specific Phobia ICD Specific Phobia Specific Phobia DSM IV Separation Anxiety Disorder Separation Anxiety ICD Separation Anxiety Disorder Separation Anxiety, GAD DSM IV Adult Separation Anxiety Disorder Separation Anxiety, ICD Adult Separation Anxiety Disorder Separation Anxiety, GAD DSM IV PTSD PTSD ICD PTSD PTSD Substance DSM IV Alcohol Abuse Alcohol Use ICD Harmful Use Alcohol Alcohol Use DSM IV Alcohol Dependence Alcohol Use ICD Alcohol Dependence Alcohol Use DSM IV Drug Abuse Illegal Substance Use ICD Harmful Use Drugs Illegal Substance Use DSM IV Drug Dependence Illegal Substance Use ICD Drug Dependence Illegal Substance Use DSM IV Nicotine Dependence Tobacco ICD Nicotine Dependence Tobacco Impulse Control DSM IV Conduct Disorder Conduct Disorder ICD Conduct Disorder Conduct Disorder, Mania, Depression, ADHD DSM IV Intermittent Explosive Disorder IED, Mania, Conduct Disorder, ADHD DSM IV Anorexia Nervosa Eating Disorders ICD Anorexia Nervosa Eating Disorders DSM IV Bulimia Nervosa Eating Disorders ICD Bulimia Nervosa Eating Disorders DSM IV Pathological Gambling Gambling, Mania ICD Pathological Gambling Gambling DSM IV Attention Deficit Disorder ADHD ICD Hyperkinetic Disorder ADHD DSM IV ODD ODD, Depression, Mania, Conduct Disorder ICD ODD ODD, Conduct Disorder Other DSM IV Premenstrual Dysphoric Disorder Premenstrual Dysphoric Disorder

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