According to the Field Representative's Manual for 1999, this set of GAD questions was included "to determine if the Sample Adult has had or still has a period lasting one month or longer when most of the time they felt worried, tense, or anxious in the past 12 months and, if so, how much they worry, if this worry has ended or is still going on and how long, how long it has affected them, how they dealt with these problems, and how much these problems interfered with their life or activities."

Respondents who indicated in WORSTILL that the period had ended were asked, "How many months or years did it go on before it ended?" Responses to this question were recorded in two variables, WORAGONO (number of units) and WORAGOTP (time period).

Respondents who indicated in WORSTILL that the period was still going on or who had an unknown answer in WORSTILL were asked about the duration of the (on-going) period of feeling worried, tense, or anxious or worrying more than most people. Their responses to the question "How many months or years has it been going on?" were recorded in two variables, WORNO (number of units) and WORTP (time period).

If the respondent's answer to WORAGONO, WORAGOTP, WORNO, or WORTP was "unknown," interviewers asked whether the period had lasted at least 6 months (WOR6MO).

The public use files of the NHIS include two summary recoded variables indicating the duration of the period of feeling worried, tense, or anxious or worrying more than most people, using a single time unit of years. These recoded variables are WORAGOYR (a recode of WORAGONO and WORAGOTP) and WORYR (a recode of WORNO and WORTP).

Respondents who passed the second set of screening questions by reporting that they had a period of feeling worried, tense or anxious or worrying more than most people that lasted for at least six months were asked a series of questions about symptoms of GAD. Respondents who reported experiencing at least one physiological symptom of GAD were also asked a series of supplemental questions that inquired about their contact with a medical doctor or other health professional, about their use of medication, drugs, or alcohol, and about how their worry interfered with daily functioning.

For more information on all the variables associated with the NHIS CIDI-SF screening scale on GAD, and for instructions on how to calculate generalized anxiety disorder scores, see WOR1MO.