According to the Field Representative's Manual for 1999, this set of questions was included "to determine if the Sample Adult has been or still is depressed in the past 12 months and, if so, how it affected them physically and emotionally, how long it has affected them, how they dealt with these problems, and how much these problems interfered with their life or activities."

The periodic mental health section of the 1999 NHIS includes questions taken from the CIDI-SF screening scales for major depression, generalized anxiety disorder, and panic attacks. More information on the generalized anxiety disorder questions can be found in WOR1MO. For more information on the panic attack questions, see PANICYR.

Respondents with an affirmative response in DEP2WKEV (IPUMS NHIS code 2) were told, "For the next few questions, please think of the two-week period during the past 12 months when these feelings were the worst," and then were asked a second screening question for dysphoric mood:

• During that time did the feelings of being sad, blue, or depressed usually last all day long, most of the day, about half of the day or less than half of the day? (DEPDAYAMT)

Respondents who indicated, in answer to the question associated with DEP2WKEV, that they were on medication/anti-depressants were skipped out of the dysphoric mood section and were asked the first question in the anhedonia section (DEPLIFUN).

Respondents who answered "All day long," "Most of the day," or "About half of the day" to the question associated with DEPDAYAMT were asked a third screening question for dysphoric mood:

• During those two weeks, did you feel this way every day, almost every day, or less often? (DEPHOWOFT)

Respondents who passed the first two screening questions (DEP2WKEV, DEPDAYAMT) and who answered "Every day" or "Almost every day" to DEPHOWOFT received a series of questions on symptoms associated with dysphoric mood. Respondents who did not pass all three dysphoric mood screening questions (DEP2WKEV, DEPDAYAMT, DEPHOWOFT) were asked a second set of screening questions on anhedonia. The set of screening questions on anhedonia mirror the screening questions on dysphoric mood, except that the symptom referenced in the anhedonia questions is "loss of interest in pleasurable activities," rather than "feeling sad, blue or depressed." Respondents who passed all three of the anhedonia screening questions were asked a series of anhedonia symptom questions similar to the series of questions asked about dysphoric mood symptoms. For more information on the anhedonia-related questions, see DEPLIFUN.

These symptom questions covered the following:

• Lost interest in most things during 2+ weeks sad/blue/depressed, past 12 months (DEPLI)

• Felt more lethargic during 2+ weeks sad/blue/depressed, past 12 months (DEPLETH)

• Weight gained/lost/same during 2+ weeks sad/blue/depressed, past 12 months (DEPWT)

• (For respondents whose weight changed) Amount of weight change during 2+ weeks sad/blue/depressed, past 12 months (DEPWTAMT)

• (For respondents whose amount of weight change was unknown) Weight changed 10+ pounds during 2+ weeks sad/blue/depressed, past 12 months (DEPWT10)

• Had trouble sleeping during 2+ weeks sad/blue/depressed, past 12 months (DEPINSOM)

• (For respondents who had trouble sleeping) How often had trouble sleeping during 2+ weeks sad/blue/depressed, past 12 months (DEPINSOMOFT)

• Had trouble concentrating during 2+ weeks sad/blue/depressed, past 12 months (DEPCONCEN)

• Felt worthless/no good during 2+ weeks sad/blue/depressed, past 12 months (DEPNOGOOD)

• Thought about death during 2+ weeks sad/blue/depressed, past 12 months (DEPSUICID)

Those who reported that their weight changed by 10+ pounds (a "Yes" response in DEPWT and either a report of 10+ pounds in DEPWTAMT or a "Yes" response in DEPWT10) and those who reported having trouble sleeping every night or nearly every night (according to DEPINSOM and DEPINSOMOFT) were also asked these supplemental questions. Specifically, these supplemental questions were:

• Total number of weeks felt sad/blue/depressed during past 12 months (DEPWKNO)

• Most recent month felt sad/blue/depressed 2+ weeks (DEPWHENMO)

• Most recent year, 1998-2000, felt sad/blue/depressed 2+ weeks (DEPWHENYR)

• Told doctor about feeling sad/blue/depressed 2+ weeks during the past 12 months (DEPTOLDDR)

• Told health professional about feeling sad/blue/depressed 2+ weeks during the past 12 months (DEPTOLDHP)

• Used medication/drugs/alcohol to cope with feeling sad/blue/depressed (DEPDRUGALC)

• Amount feeling sad/blue/depressed 2+ weeks during the past 12 months interfered with life (DEPINTFERE)

The skip pattern found in the NHIS survey instrument for the first screening question, DEP2WKEV, differs slightly from that in the WHO CIDI-SF instrument. In the NHIS CIDI-SF instrument, respondents who indicate that they are on medication/anti-depressants are skipped out of the dysphoric mood section and receive the first question in the anhedonia section (DEPLIFUN). In contrast, according to the scoring guide for the World Health Organization's CIDI-SF, respondents who volunteer that they are on medication/anti-depressants in DEP2WKEV go on to the second screening question for dysphoric mood (DEPDAYAMT).

The WHO CIDI-SF skip pattern for the second screening question for dysphoric mood, DEPDAYAMT, is also different from that in the NHIS instrument. In the WHO CIDI-SF instrument, only respondents who report experiencing feelings of being sad, blue, or depressed "All day long" or "Most of the day" in DEPDAYAMT receive the third screening question (DEPHOWOFT). However, in the NHIS instrument, respondents who answer "About half of the day" in DEPDAYAMT also go on to DEPHOWOFT.

Because of these differences, scoring the screening scale for major depression yields different results, depending on whether guided by the WHO CIDI-SF instrument or the NHIS version of the instrument (see below).

According to the Appendix on Adult Mental Health Documentation included in the 1999 NHIS Survey Description, the "NCHS suggests that individual CIDI-SF items [as used in the NHIS] not be used for purposes beyond those recommended by the World Health Organization (WHO)." The Survey Description then directs users to the WHO's website for instructions on how to calculate the probability of psychiatric diagnosis based on responses to the CIDI-SF items.

According to the WHO CIDI-SF guidelines, respondents must pass all three screening questions in the dysphoric mood section (DEP2WKEV, DEPDAYAMT, DEPHOWOFT) to receive further questions on depressive symptoms. Respondents who do not pass this series of screening questions, and who do not pass the series of screening questions in the anhedonia section, receive a score of 0 (zero probability of psychiatric caseness for major depression).

Respondents who pass all three screening questions on dysphoric mood and answer the depressive symptom questions receive one point for each of the following responses about depressive symptoms:

• "Yes" in DEPLI (Lost interest in most things)

• "Yes" in DEPLETH (Felt more lethargic than usual)

• "Gain," "Lose," or "Volunteered 'both gained and lost weight'" in DEPWT (Gained and/or lost weight) and "10+" in DEPWTAMT (Amount of weight change 10+ pounds) or "Yes" in DEPWT10 (Weight changed 10+ pounds)

• "Yes" in DEPINSOM (Had trouble sleeping) and "Every night" or "Nearly every night" in DEPINSOMOFT (How often had trouble sleeping)

• "Yes" in DEPCONCEN (Had trouble concentrating)

• "Yes" in DEPNOGOOD (Felt worthless or no good)

• "Yes" in DEPSUICID (Thought about death)

Summing the number of endorsed items results in a major depression score ranging from 0-7. Respondents with a score of 3 or more are classified as a probable case for having major depression.

First, for the second screening question (DEPDAYAMT), the NHIS instrument used less stringent criteria in its skip pattern than did the WHO CIDI-SF instrument. With the NHIS instrument, respondents who reported experiencing feelings of being sad, blue, or depressed "All day long," "Most of the day," or "About half the day" in response to the second screening question (DEPDAYAMT) were questioned further about dysphoric mood. In contrast, only respondents answering "All day long" or "Most of the day" to DEPDAYAMT were questioned further about dysphoric mood using the WHO guidelines. By definition, therefore, more people will be classified as probable cases for major depression using the NHIS version of the CIDI-SF than with the WHO version of the CIDI-SF.

Second, as mentioned above, according to the CIDI-SF scoring guide published by the World Health Organization, respondents who report taking medication/anti-depressants in DEP2WKEV are questioned further about their symptoms of dysphoric mood. In contrast, in the NHIS version of the CIDI-SF respondents who indicate that they are taking medication/anti-depressants receive no further questions in the dysphoric mood section and move on to the first screening question in the anhedonia section. However, an article published by the Department of Health and Human Services, based on these NHIS data, classified all respondents who volunteered they were on medication/anti-depressants (in either the dysphoric mood or the anhedonia section) as probable cases for major depression (See mentalhealth.samhsa.gov/publications/allpubs/SMA04-3938/Chapter08.asp). Again, using this last criterion (that all persons taking anti-depressants are probable cases for major depression) means that more people will be classified as probable cases for major depression with the NHIS survey instrument than with the CIDI-SF instrument.