GAD-7

Generalised Anxiety Disorder Scale - GAD-7

Measuring: Identify probable cases of Generalized anxiety disorder (GAD).

Number of Items: 7

Item	Question Wording	TILDA Variable
1	Feeling nervous, anxious or on edge.	SCQAnxiety1
2	Not being able to stop or control worrying.	SCQAnxiety2
3	Worrying too much about different things.	SCQAnxiety3
4	Trouble relaxing.	SCQAnxiety4
5	Feeling afraid as if something awful might happen.	SCQAnxiety5
6	Becoming easily annoyed or irritable.	SCQAnxiety6
7	I get sudden feelings of panic.	SCQAnxiety7

Scoring Method:

4-point Likert Scale.

0 = Not at all

1 = Several days

2 = More than half the days

3 = Nearly every day

A cumulative score is generated.
Scores of 10 fulfils the criteria for general Anxiety Disorder in the last 12 months.

Citation: Spitzer, R. L., Kroenke, K., Williams, J. B., & Lowe, B. (2006). A brief measure for assessing generalized anxiety disorder: the GAD-7.Â Archives of internal medicine,Â 166(10), 1092–1097. https://doi.org/10.1001/archinte.166.10.1092

Example TILDA Papers:

McDowell, C. P., Dishman, R. K., Vancampfort, D., Hallgren, M., Stubbs, B., MacDonncha, C., & Herring, M. P. (2018). Physical activity and generalized anxiety disorder: results from The Irish Longitudinal Study on Ageing (TILDA). International journal of epidemiology, 47(5), 1443-1453. https://doi.org/10.1093/ije/dyy141

Code

mvdecode Anxiety*, mv(-99=.\-812=.\-823=.\-834=.)
gen GAD7 = 0 if in_scq == 1

foreach posq in SCQAnxiety1 SCQAnxiety2 SCQAnxiety3 SCQAnxiety4 SCQAnxiety5 SCQAnxiety6 SCQAnxiety7 {
 replace GAD7 = GAD7 + (`posq'-1) 
 replace GAD7 = . if `posq' == 99 | `posq' <0
  replace GAD7 = . if `posq' == 98
}

label variable GAD7 "Generalised Anxiety Scale (GAD7)"
notes GAD7: Anxiety-GAD-7   Ordinal. Questions are all 3 2 1 0, ie coded score minus 1, higher score more anxiety

Download Stata .do file

gad_items <- paste0("SCQAnxiety", 1:7)

for (v in gad_items) {
  data[[v]][data[[v]] %in% c(-99, -812, -823, -834)] <- NA_real_
}

data$GAD7 <- NA_real_
data$GAD7[!is.na(data$in_scq) & data$in_scq == 1] <- 0

for (v in gad_items) {
  data$GAD7 <- data$GAD7 + (data[[v]] - 1)
  data$GAD7[data[[v]] == 99 |
            data[[v]] == 98 |
            (!is.na(data[[v]]) & data[[v]] < 0)] <- NA_real_
}

attr(data$GAD7, "label") <- "Generalised Anxiety Scale (GAD7)"
attr(data$GAD7, "note") <- paste(
  "Anxiety-GAD-7 Ordinal. Questions are all 3 2 1 0, ie coded score minus 1,",
  "higher score more anxiety"
)

Download R file

* Recode special missing values used in the source.
RECODE SCQAnxiety1 SCQAnxiety2 SCQAnxiety3 SCQAnxiety4
       SCQAnxiety5 SCQAnxiety6 SCQAnxiety7
       (-99 = SYSMIS) (-812 = SYSMIS) (-823 = SYSMIS) (-834 = SYSMIS).

COMPUTE GAD7 = $SYSMIS.
IF (in_scq = 1) GAD7 = 0.

COMPUTE GAD7 = GAD7 + (SCQAnxiety1 - 1).
IF (SCQAnxiety1 = 99 OR SCQAnxiety1 = 98 OR SCQAnxiety1 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety2 - 1).
IF (SCQAnxiety2 = 99 OR SCQAnxiety2 = 98 OR SCQAnxiety2 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety3 - 1).
IF (SCQAnxiety3 = 99 OR SCQAnxiety3 = 98 OR SCQAnxiety3 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety4 - 1).
IF (SCQAnxiety4 = 99 OR SCQAnxiety4 = 98 OR SCQAnxiety4 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety5 - 1).
IF (SCQAnxiety5 = 99 OR SCQAnxiety5 = 98 OR SCQAnxiety5 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety6 - 1).
IF (SCQAnxiety6 = 99 OR SCQAnxiety6 = 98 OR SCQAnxiety6 < 0) GAD7 = $SYSMIS.

COMPUTE GAD7 = GAD7 + (SCQAnxiety7 - 1).
IF (SCQAnxiety7 = 99 OR SCQAnxiety7 = 98 OR SCQAnxiety7 < 0) GAD7 = $SYSMIS.

VARIABLE LABELS GAD7 "Generalised Anxiety Scale (GAD7)".

* Note from Stata:
* Anxiety-GAD-7 Ordinal. Questions are all 3 2 1 0, ie coded score minus 1;
* higher score indicates more anxiety.

EXECUTE.

Download SPSS .sps file