Abstract
While the Patient Health Questionnaire 9 (PHQ-9) and General Anxiety Disorder 7 (GAD-7) are frequently used in mental health research, few studies have reported comprehensive data on these measures from population or community samples. The PHQ-9 and GAD-7 were used as indicators of symptoms of depression and anxiety in a national online anonymous survey to assess the mental health of adults in Australia during the COVID-19 restrictions. The aim of this study was to describe gender- and age-specific PHQ-9 and GAD-7 item and summary data contributed by those who completed this survey. Data were analysed descriptively. Complete survey responses were contributed by 13,829 people. For both measures, item-by-item results, summary statistics (mean, standard deviation, minimum, maximum, median and interquartile range) and prevalence of severity categories are reported for the whole sample, and disaggregated by gender and age groups. These comprehensive data provide a useful point of comparison for future COVID-19-related or other research among population or community samples. Other researchers are encouraged to report detailed PHQ-9 and GAD-7 data in the future, to enable and promote relevant between-group comparisons.
Keywords: Patient Health Questionnaire, Anxiety, Depression, Mental health, Coronavirus
1. INTRODUCTION
Short and understandable screening instruments are useful for detecting and assessing severity of symptoms of depression and anxiety in clinical and research settings. The Patient Health Questionnaire 9 (PHQ-9) and the General Anxiety Disorder 7 (GAD-7) scale are well-established instruments for screening for symptoms of depression and generalised anxiety respectively. Both have been formally validated against diagnostic clinical interviews to establish the sensitivity, specificity and positive and negative predictive values of cut-off scores, and are used widely in clinical research (Kroenke et al., 2001; Spitzer et al., 2006).
However, the PHQ-9 and GAD-7 have been less widely used to ascertain population or community prevalence of symptoms of depression or generalised anxiety. After searching the literature, we found a limited set of studies that had used one or both of these measures (see Table 1 ) to assess depression and anxiety among randomly-selected samples of people drawn from general communities. Some studies involved a specific population group: people attending general practice (Carey et al., 2014; Pirkis et al., 2009), university students (Farrer et al., 2016), or older women (Hammarberg et al., 2019). Most studies only reported the prevalence of moderate to severe symptoms of depression (PHQ-9 score ≥10) or generalised anxiety (GAD-7 score ≥10). The prevalence of those with no or mild symptoms, and a breakdown of moderate, moderately severe and severe symptoms have been less frequently reported. Further, few studies reported mean scores and indicators of variance like standard deviations of the population-level data. Only one included item-by-item results for the GAD-7 (Hinz et al., 2017) and none included item-by-item results for the PHQ-9.
Table 1.
Summary of comparison data collected using the PHQ-9 and/or GAD-7
Author (Year) | Country | Participants | Prevalence | Mean (±SD) | Item-by-item results | Data disaggregated | |
---|---|---|---|---|---|---|---|
PHQ-9 | |||||||
Participants randomly selected from the general community | |||||||
Patten and Schopflocher (2009) | Canada | 3304 people aged at least 18 years | Moderate-severe: 3.3% | NR | NR | NR | |
Shim et al. (2011) | USA | 10,283 people aged at least 18 years | Mild: 14.8%; moderate: 4.52%; moderately severe: 1.8%; severe: 0.6% | NR | NR | Age, gender | |
Johansson et al. (2013) | Sweden | 1329 people aged at least 18 years | Moderate: 6.4%; moderately severe-severe: 4.4% | 3.7 | NR | Gender | |
Kocalevent et al. (2013) | Germany | 5018 people aged at least 18 years | No symptoms: 76.4%; mild: 18.1%; moderate: 4.3%; moderately severe-severe: 1.3% | Men: 2.7 (±3.5); women: 3.1 (±3.5) | NR | Age, gender | |
Kiely and Butterworth (2015) | Australia | 546 people aged 32 to 35 years and 1515 aged 52 to 58 years |
3.0%* | No prior 30-day diagnosis: 3.71 (±3.94); prior 30-day diagnosis: 12.34 (±6.64)* | NR | NR | |
Participants selected from people attending general practices | |||||||
Pirkis et al. (2009) | Australia | >22,000 people aged >59 consulting a GP | Moderate-severe: 8.2% | NR | NR | Gender | |
Carey et al. (2014) | Australia | 1004 people consulting a GP | No symptoms: 66.3%; mild: 20.8%; moderate: 7.1%; moderately severe: 3.4%; severe: 2.4% | NR | NR | NR | |
Specific population groups | |||||||
Farrer et al. (2016) | Australia | 611 university students | Moderate-severe: 7.9% | 7.33 (±5.73) | NR | NR | |
GAD-7 | |||||||
Participants randomly selected from the general community | |||||||
Johansson et al. (2013) | Sweden | 1329 people aged at least 18 years | ≥8: 14.7% | 3.59 | NR | Gender | |
Hinz et al. (2017) | Germany | 9721 people aged at least 18 years | No symptoms: 68.6%; mild: 25.5%; moderate: 4.7%; severe: 1.2% | 3.57 | Yes; mean score for each item, by gender | Age, gender | |
Specific population groups | |||||||
Farrer et al. (2016) | Australia | 611 university students | Moderate-severe: 17.5% | 5.60 (±5.04) | NR | NR | |
Hammarberg et al. (2019) | Australia | 4947 women aged > 49 years from the general community responding to an online survey | Moderate-severe: 10.6% | NR | NR | Age |
NR – not reported
*In Kiely and Butterworth (2015), this prevalence was estimated using the World Mental Health Composite International Diagnostic Interview (WMH-CIDI), and the means are reported separately for those with and without a 30-day diagnosis (diagnosed using the WMH-CIDI)
We conducted a nationwide online survey to assess the mental health of adults living in Australia during the first month of COVID-19 restrictions (Fisher et al., 2020). The brief and anonymously-completed survey included the PHQ-9 and GAD-7 as indicators of prevalence and severity of symptoms of depression and anxiety. As the whole population was affected, it was not possible to establish a comparison group who were not living with COVID-19 restrictions, so we turned to the available published evidence about these measures in general communities at non-COVID times as a comparator. We found few published studies reporting comprehensive PHQ-9 and GAD-7 data from population or general community samples. With a large and nationally representative sample, the PHQ-9 and GAD-7 data from our survey can provide valuable reference data for future studies (Fisher et al., 2020). The aim of this study was to describe detailed gender- and age-specific PHQ-9 and GAD-7 item and summary data collected from adults in Australia during the COVID-19 restrictions.
2. METHODS
The methods of this study have been described in detail elsewhere (Fisher et al., 2020).
2.1. Design, setting and participants
This study was a short online survey of people aged at least 18 years and living in Australia. The survey was created in Qualtrics Insight Platform, and was open to respondents from 3 April to midnight on 2 May 2020. The survey link was displayed on the Monash University website, and information about the survey was disseminated through social and traditional media, organisational and personal networks.
2.2. Data source
Data were collected using a questionnaire, which included the PHQ-9 and GAD-7, as well as study-specific questions. In this paper, only two study-specific questions, ‘Are you: female, male, or other?’ and ‘How old are you?’, will be used in analyses.
2.2.1. Patient Health Questionnaire 9 (PHQ-9)
The PHQ-9, a shorter version of the complete PHQ, is a nine-item self-report scale designed to assess symptoms of depression. The PHQ-9 is comprised of the nine criteria used in the DSM-IV to diagnose depressive disorders. Each of the nine items can be scored from 0 (not at all) to 3 (nearly every day), and the total scale score ranges from 0-27. Symptom severity can be assessed through the total score, where PHQ-9 scores of 5-9: mild, 10-14: moderate, 15-19: moderately severe, and ≥20: severe depressive symptoms.
The PHQ-9 has been formally validated against structured diagnostic interviews administered by a mental health professional; PHQ-9 score ≥10 has a sensitivity of 88% and a specificity of 88% to detect Major Depression (Kroenke et al., 2001).
2.2.2. General Anxiety Disorder 7 (GAD-7)
The GAD-7 is a brief, seven-item self-report scale designed to assess generalised anxiety in primary care settings. Similar to the PHQ-9, each of the seven items are scored from 0 (not at all) to 3 (nearly every day). The total GAD-7 scale score ranges from 0-21. Cut-offs can be used to describe symptom severity; GAD-7 scores of 5-9: mild, 10-14: moderate, ≥15: severe anxiety symptoms. When formally validated against diagnostic psychiatric interviews, a GAD-7 score of ≥10 has a sensitivity of 89% and specificity of 82% to detect Generalised Anxiety Disorder (Spitzer et al., 2006).
2.3. Data management and analysis
Data were analysed descriptively. For both the PHQ-9 and GAD-7, the number and frequency of responses are reported at an item-by-item level, for the total sample, and stratified by gender and age group. Summary statistics, including mean, standard deviation, minimum and maximum values, median and interquartile range, for both measures for the total sample and gender and age groups were calculated. The number and frequency of participants in each symptom severity category for both depression and anxiety were calculated, by whole sample, gender and age groups.
2.4. Ethics approval
Ethics approval was given by the Monash University Human Research Ethics Committee (ID: 2020-24090-42716).
3. RESULTS
The survey was completed by 13,829 respondents aged 18 or over and living in Australia. Demographic characteristics of the study sample are shown in Table 2 .
Table 2.
Demographic characteristics of the study sample (N = 13,829)
n | % | |
---|---|---|
Gender | ||
Women | 10,434 | 75.5 |
Men | 3,328 | 24.1 |
Other | 67 | 0.5 |
State/Territory | ||
Australian Capital Territory | 465 | 3.4 |
New South Wales | 2,753 | 19.9 |
Northern Territory | 109 | 0.8 |
Queensland | 1,939 | 14 |
South Australia | 836 | 6.0 |
Tasmania | 445 | 3.2 |
Victoria | 6,105 | 44.1 |
Western Australia | 1,177 | 8.5 |
Age group | ||
18-29 | 1337 | 9.7 |
30-49 | 5148 | 37.2 |
50-69 | 5897 | 42.6 |
70+ | 1447 | 10.5 |
The distribution of the frequency of depressive symptoms (‘not at all’ to ‘nearly every day’) for each item of the PHQ-9, for the whole sample, and disaggregated by gender are shown in Table 3 . Item-by-item results for the PHQ-9, disaggregated by age are shown in Table 4 . In Tables 5 and 6 , the distribution of frequency of anxiety symptoms for each item of the GAD-7 are shown, for the whole sample, and stratified by gender and age.
Table 3.
PHQ-9 item-by-item results, for the total sample and stratified by gender
Whole sample (N=13,829) | Women (N=10,434) | Men (N=3,328) | Other (N=67) | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | |
1. Little interest or pleasure in doing things | 6455 (46.7) |
4776 (34.5) |
1596 (11.5) |
1002 (7.2) |
4730 (45.3) |
3755 (36) |
1199 (11.5) |
750 (7.2) |
1700 (51.1) |
1004 (30.2) |
383 (11.5) |
241 (7.2) |
25 (37.3) |
17 (25.4) |
14 (20.9) |
11 (16.4) |
2. Feeling down, depressed, or hopeless | 6331 (45.8) |
5215 (37.7) |
1370 (9.9) |
913 (6.6) |
4519 (43.3) |
4162 (39.9) |
1062 (10.2) |
691 (6.6) |
1786 (53.7) |
1031 (31) |
302 (9.1) |
209 (6.3) |
26 (38.8) |
22 (32.8) |
6 (9) |
13 (19.4) |
3. Trouble falling or staying asleep, or sleeping too much | 5003 (36.2) |
4723 (34.2) |
2165 (15.7) |
1938 (14) |
3425 (32.8) |
3727 (35.7) |
1745 (16.7) |
1537 (14.7) |
1553 (46.7) |
980 (29.4) |
411 (12.3) |
384 (11.5) |
25 (37.3) |
16 (23.9) |
9 (13.4) |
17 (25.4) |
4. Feeling tired or having little energy | 4210 (30.4) |
5614 (40.6) |
2388 (17.3) |
1617 (11.7) |
2895 (27.7) |
4347 (41.7) |
1897 (18.2) |
1295 (12.4) |
1299 (39) |
1246 (37.4) |
480 (14.4) |
303 (9.1) |
16 (23.9) |
21 (31.3) |
11 (16.4) |
19 (28.4) |
5. Poor appetite or overeating | 6484 (46.9) |
3733 (27) |
2137 (15.5) |
1475 (10.7) |
4543 (43.5) |
2941 (28.2) |
1743 (16.7) |
1207 (11.6) |
1912 (57.5) |
779 (23.4) |
386 (11.6) |
251 (7.5) |
29 (43.3) |
13 (19.4) |
8 (11.9) |
17 (25.4) |
6. Feeling bad about yourself, or that you are a failure, or have let yourself or your family down | 8827 (63.8) |
2876 (20.8) |
1190 (8.6) |
936 (6.8) |
6471 (62) |
2296 (22) |
944 (9) |
723 (6.9) |
2323 (69.8) |
567 (17) |
242 (7.3) |
196 (5.9) |
33 (49.3) |
13 (19.4) |
4 (6) |
17 (25.4) |
7. Trouble concentrating on things, such as reading the newspaper or watching television | 7404 (53.5) |
3757 (27.2) |
1661 (12) |
1007 (7.3) |
5331 (51.1) |
2963 (28.4) |
1335 (12.8) |
805 (7.7) |
2048 (61.5) |
779 (23.4) |
315 (9.5) |
186 (5.6) |
25 (37.3) |
15 (22.4) |
11 (16.4) |
16 (23.9) |
8. Moving or speaking so slowly that other people could have noticed. Or the opposite, being so fidgety or restless that you have been moving around a lot more than usual | 11079 (80.1) |
1781 (12.9) |
654 (4.7) |
315 (2.3) |
8298 (79.5) |
1392 (13.3) |
498 (4.8) |
246 (2.4) |
2742 (82.4) |
374 (11.2) |
149 (4.5) |
63 (1.9) |
39 (58.2) |
15 (22.4) |
7 (10.4) |
6 (9) |
9. Thoughts that you would be better or dead, or of hurting yourself in some way | 12137 (87.8) |
1075 (7.8) |
356 (2.6) |
261 (1.9) |
9235 (88.5) |
757 (7.3) |
250 (2.4) |
192 (1.8) |
2858 (85.9) |
308 (9.3) |
101 (3) |
61 (1.8) |
44 (65.7) |
10 (14.9) |
5 (7.5) |
8 (11.9) |
*Data cell: number (%)
Table 4.
PHQ-9 item-by-item results stratified by age
18-29 (N=1,337) | 30-49 (N=5,148) | 50-69 (N=5,897) | 70+ (N=1,447) | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | |
1. Little interest or pleasure in doing things | 333 (24.9) | 545 (40.8) | 291 (21.8) | 168 (12.6) | 2098 (40.8) | 1984 (38.5) | 648 (12.6) | 418 (8.1) | 3083 (52.3) | 1893 (32.1) | 568 (9.6) | 353 (6.0) | 941 (65) | 354 (24.5) | 89 (6.2) |
63 (4.4) |
2. Feeling down, depressed, or hopeless | 347 (26) | 585 (43.8) | 228 (17.1) | 177 (13.2) | 1966 (38.2) | 2191 (42.6) | 605 (11.8) | 386 (7.5) | 3053 (51.8) | 2069 (35.1) | 472 (8) | 303 (5.1) | 965 (66.7) | 370 (25.6) | 65 (4.5) |
47 (3.2) |
3. Trouble falling or staying asleep, or sleeping too much | 339 (25.4) | 408 (30.5) | 274 (20.5) | 316 (23.6) | 1605 (31.2) | 1819 (35.3) | 918 (17.8) | 806 (15.7) | 2294 (38.9) | 2044 (34.7) | 843 (14.3) | 716 (12.1) | 765 (52.9) | 452 (31.2) | 130 (9.0) | 100 (6.9) |
4. Feeling tired or having little energy | 201 (15) | 497 (37.2) | 371 (27.7) | 268 (20) | 1129 (21.9) | 2213 (43) | 1071 (20.8) | 735 (14.3) | 2168 (36.8) | 2389 (40.5) | 824 (14) | 516 (8.8) | 712 (49.2) | 515 (35.6) | 122 (8.4) | 98 (6.8) |
5. Poor appetite or overeating | 386 (28.9) | 384 (28.7) | 321 (24) | 246 (18.4) | 1935 (37.6) | 1558 (30.3) | 961 (18.7) | 694 (13.5) | 3130 (53.1) | 1534 (26) | 764 (13) | 469 (8.0) | 1033 (71.4) | 257 (17.8) | 91 (6.3) |
66 (4.6) |
6. Feeling bad about yourself, or that you are a failure, or have let yourself or your family down | 622 (46.5) | 351 (26.3) | 187 (14) | 177 (13.2) | 2869 (55.7) | 1257 (24.4) | 580 (11.3) | 442 (8.6) | 4118 (69.8) | 1103 (18.7) | 386 (6.5) | 290 (4.9) | 1218 (84.2) | 165 (11.4) | 37 (2.6) |
27 (1.9) |
7. Trouble concentrating on things, such as reading the newspaper or watching television | 433 (32.4) | 429 (32.1) | 261 (19.5) | 214 (16) | 2403 (46.7) | 1541 (29.9) | 747 (14.5) | 457 (8.9) | 3471 (58.9) | 1539 (26.1) | 587 (10.0) | 300 (5.1) | 1097 (75.8) | 248 (17.1) | 66 (4.6) |
36 (2.5) |
8. Moving or speaking so slowly that other people could have noticed. Or the opposite, being so fidgety or restless that you have been moving around a lot more than usual | 873 (65.3) | 284 (21.2) | 112 (8.4) | 68 (5.1) |
3979 (77.3) | 754 (14.6) | 284 (5.5) | 131 (2.5) | 4923 (83.5) | 646 (11) | 226 (3.8) | 102 (1.7) | 1304 (90.1) | 97 (6.7) |
32 (2.2) |
14 (1.0) |
9. Thoughts that you would be better or dead, or of hurting yourself in some way | 1063 (79.5) | 159 (11.9) | 62 (4.6) |
53 (4) |
4477 (87) | 426 (8.3) | 149 (2.9) | 96 (1.9) |
5261 (89.2) | 409 (6.9) | 128 (2.2) | 99 (1.7) |
1336 (92.3) | 81 (5.6) |
17 (1.2) |
13 (0.9) |
*Data cell: number (%)
Table 5.
GAD-7 item-by-item results, for the total sample and stratified by gender
Whole sample (N=13,829) | Women (N=10,434) | Men (N=3,328) | Other (N=67) | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | |
Feeling nervous, anxious or on edge | 4849 (35.1) |
5542 (40.1) |
1941 (14) |
1497 (10.8) |
3160 (30.3) |
4415 (42.3) |
1605 (15.4) |
1254 (12) |
1668 (50.1) |
1108 (33.3) |
326 (9.8) |
226 (6.8) |
21 (31.3) |
19 (28.4) |
10 (14.9) |
17 (25.4) |
Not being able to stop or control worrying | 7511 (54.3) |
3993 (28.9) |
1408 (10.2) |
917 (6.6) |
5259 (50.4) |
3248 (31.1) |
1170 (11.2) |
757 (7.3) |
2222 (66.8) |
733 (22) |
226 (6.8) |
147 (4.4) |
30 (44.8) |
12 (17.9) |
12 (17.9) |
13 (19.4) |
Worrying too much about different things | 6148 (44.5) |
4946 (35.8) |
1656 (12) |
1079 (7.8) |
4228 (40.5) |
3973 (38.1) |
1347 (12.9) |
886 (8.5) |
1896 (57) |
952 (28.6) |
301 (9) |
179 (5.4) |
24 (35.8) |
21 (31.3) |
8 (11.9) |
14 (20.9) |
Trouble relaxing | 5915 (42.8) |
4875 (35.3) |
1809 (13.1) |
1230 (8.9) |
4118 (39.5) |
3868 (37.1) |
1464 (14) |
984 (9.4) |
1775 (53.3) |
990 (29.7) |
332 (10) |
231 (6.9) |
22 (32.8) |
17 (25.4) |
13 (19.4) |
15 (22.4) |
Being so restless that it is hard to sit still | 9399 (68) |
3022 (21.9) |
932 (6.7) |
476 (3.4) |
6984 (66.9) |
2370 (22.7) |
715 (6.9) |
365 (3.5) |
2381 (71.5) |
640 (19.2) |
203 (6.1) |
104 (3.1) |
34 (50.7) |
12 (17.9) |
14 (20.9) |
7 (10.4) |
Becoming easily annoying or irritable | 5494 (39.7) |
5277 (38.2) |
1925 (13.9) |
1133 (8.2) |
3855 (36.9) |
4110 (39.4) |
1531 (14.7) |
938 (9) |
1616 (48.6) |
1147 (34.5) |
381 (11.4) |
184 (5.5) |
23 (34.3) |
20 (29.9) |
13 (19.4) |
11 (16.4) |
Feeling afraid as if something awful might happen | 7432 (53.7) |
4133 (29.9) |
1431 (10.3) |
833 (6) |
5265 (50.5) |
3340 (32) |
1164 (11.2) |
665 (6.4) |
2137 (64.2) |
779 (23.4) |
257 (7.7) |
155 (4.7) |
30 (44.8) |
14 (20.9) |
10 (14.9) |
13 (19.4) |
*Data cell: number (%)
Table 6.
GAD-7 item-by-item results, stratified by age
18-29 (N=1,337) | 30-49 (N=5,148) | 50-69 (N=5,897) | 70+ (N=1,447) | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | Not at all | Several days | More than half the days | Nearly every day | |
Feeling nervous, anxious or on edge | 282 (21.1) | 494 (36.9) | 298 (22.3) | 263 (19.7) | 1279 (24.8) | 2228 (43.3) | 915 (17.8) | 726 (14.1) | 2402 (40.7) | 2361 (40) | 660 (11.2) | 474 (8.0) | 886 (61.2) | 459 (31.7) | 68 (4.7) |
34 (2.3) |
Not being able to stop or control worrying | 524 (39.2) | 411 (30.7) | 233 (17.4) | 169 (12.6) | 2403 (46.7) | 1673 (32.5) | 653 (12.7) | 419 (8.1) | 3488 (59.1) | 1644 (27.9) | 465 (7.9) | 300 (5.1) | 1096 (75.7) | 265 (18.3) | 57 (3.9) |
29 (2.0) |
Worrying too much about different things | 393 (29.4) | 484 (36.2) | 259 (19.4) | 201 (15) | 1891 (36.7) | 1975 (38.4) | 768 (14.9) | 514 (10) | 2910 (49.3) | 2103 (35.7) | 555 (9.4) | 329 (5.6) | 954 (65.9) | 384 (26.5) | 74 (5.1) |
35 (2.4) |
Trouble relaxing | 385 (28.8) | 477 (35.7) | 264 (19.7) | 211 (15.8) | 1668 (32.4) | 1992 (38.7) | 861 (16.7) | 627 (12.2) | 2867 (48.6) | 2049 (34.7) | 615 (10.4) | 366 (6.2) | 995 (68.8) | 357 (24.7) | 69 (4.8) |
26 (1.8) |
Being so restless that it is hard to sit still | 695 (52) | 373 (27.9) | 162 (12.1) | 107 (8) | 3255 (63.2) | 1266 (24.6) | 412 (8.0) | 215 (4.2) | 4235 (71.8) | 1200 (20.3) | 322 (5.5) | 140 (2.4) | 1214 (83.9) | 183 (12.6) | 36 (2.5) |
14 (1.0) |
Becoming easily annoying or irritable | 362 (27.1) | 485 (36.3) | 296 (22.1) | 194 (14.5) | 1339 (26) | 2222 (43.2) | 974 (18.9) | 613 (11.9) | 2849 (48.3) | 2162 (36.7) | 591 (10) | 295 (5) | 944 (65.2) | 408 (28.2) | 64 (4.4) |
31 (2.1) |
Feeling afraid as if something awful might happen | 599 (44.8) | 400 (29.9) | 202 (15.1) | 136 (10.2) | 2500 (48.6) | 1623 (31.5) | 662 (12.9) | 363 (7.1) | 3284 (55.7) | 1800 (30.5) | 513 (8.7) | 300 (5.1) | 1049 (72.5) | 310 (21.4) | 54 (3.7) |
34 (2.3) |
*Data cell: number (%)
In Table 7 , the mean, standard deviation, minimum and maximum values, median and interquartile range of the PHQ-9 and GAD-7 total scores are shown. These summary statistics are presented for the whole sample, and also by gender and age. The prevalence of depression and anxiety by symptom severity is displayed in Table 8 .
Table 7.
Mean, minimum, maximum, median and interquartile range of PHQ-9 and GAD-7 total scores
PHQ-9 | GAD-7 | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Mean (±SD) | Minimum | Maximum | Median | IQR | Mean (±SD) | Minimum | Maximum | Median | IQR | |
Whole sample | 6.4 (±6.0) | 0 | 27 | 5 | 2-9 | 5.5 (±5.3) | 0 | 21 | 4 | 1-8 |
Gender | ||||||||||
Women | 6.7 (±6.0) | 0 | 27 | 5 | 2-10 | 5.8 (±5.3) | 0 | 21 | 5 | 2-8 |
Men | 5.5 (±5.9) | 0 | 27 | 4 | 1-8 | 4.2 (±5.0) | 0 | 21 | 2 | 0-6 |
Other | 9.9 (±8.3) | 0 | 27 | 9 | 2-17 | 8.1 (±7.0) | 0 | 21 | 7 | 2-11 |
Age | ||||||||||
18-29 | 9.7 (±6.5) | 0 | 27 | 8 | 4-14 | 7.8 (±5.9) | 0 | 21 | 7 | 3-12 |
30-49 | 7.4 (±6.0) | 0 | 27 | 6 | 3-11 | 6.6 (±5.4) | 0 | 21 | 5 | 2-10 |
50-69 | 5.5 (±5.6) | 0 | 27 | 4 | 1-8 | 4.6 (±4.9) | 0 | 21 | 3 | 1-7 |
70+ | 3.6 (±4.6) | 0 | 27 | 2 | 0-5 | 2.6 (±3.6) | 0 | 21 | 2 | 0-4 |
SD: standard deviation, IQR: interquartile range
Table 8.
Prevalence of depression and anxiety by symptom severity, stratified by gender and age
n (%) | ||||||||
---|---|---|---|---|---|---|---|---|
Whole sample | Women | Men | Other | 18-29 | 30-49 | 50-69 | 70+ | |
Depression (PHQ-9 score) | ||||||||
No symptoms (<5) | 6598 (47.7) | 4698 (45) | 1875 (56.3) | 25 (37.3) | 335 (25.1) | 2012 (39.1) | 3206 (54.4) | 1045 (72.2) |
Mild (5-9) | 3791 (27.4) | 2996 (28.7) | 785 (23.6) | 10 (14.9) | 415 (31) | 1574 (30.6) | 1549 (26.3) | 253 (17.5) |
Moderate (10-14) | 1886 (13.6) | 1533 (14.7) | 341 (10.2) | 12 (17.9) | 291 (21.8) | 876 (17) | 634 (10.8) | 85 (5.9) |
Moderately severe (15-19) | 937 (6.8) | 740 (7.1) | 189 (5.7) | 8 (11.9) | 171 (12.8) | 419 (8.1) | 310 (5.3) | 37 (2.6) |
Severe (≥20) | 617 (4.5) | 467 (4.5) | 138 (4.1) | 12 (17.9) | 125 (9.3) | 267 (5.2) | 198 (3.4) | 27 (1.9) |
Anxiety (GAD-7 score) | ||||||||
No symptoms (<5) | 7394 (53.5) | 5186 (49.7) | 2179 (65.5) | 29 (43.3) | 473 (35.4) | 2278 (44.3) | 3511 (59.5) | 1132 (78.2) |
Mild (5-9) | 3661 (26.5) | 2973 (28.5) | 677 (20.3) | 11 (16.4) | 410 (30.7) | 1527 (29.7) | 1499 (25.4) | 225 (15.5) |
Moderate (10-14) | 1621 (11.7) | 1339 (12.8) | 269 (8.1) | 13 (19.4) | 236 (17.7) | 789 (15.3) | 531 (9) | 65 (4.5) |
Severe (≥15) | 1153 (8.3) | 936 (9) | 203 (6.1) | 14 (20.9) | 218 (16.3) | 554 (10.8) | 356 (6) | 25 (1.7) |
4. DISCUSSION
This survey is, to our knowledge, one of the first observations of the impact of COVID-19 restrictions on the mental health of adults in Australia. Its major strength is that it yields the largest PHQ-9 and GAD-7 dataset from the general community to date in Australia, and is among the largest in the world. We acknowledge the limitation that online surveys are less accessible to people with limited internet access or technological literacy, and people with limited English proficiency. In our first paper, we investigated the prevalence of clinically significant symptoms of depression and anxiety, and the factors that were associated with this (Fisher et al., 2020). In that paper, we only reported prevalence of mild and clinically significant depression and anxiety, and mean PHQ-9 and GAD-7 scores. The aim of this paper was to report descriptive age- and gender-specific reference data for future research using the PHQ-9 and GAD-7.
There are several reasons for describing detailed results from mental health measures, such as the PHQ-9 and GAD-7. First, the item-by-item breakdown of each measure allows readers to see and interpret the frequency distribution of each symptom. When the measures are presented item-by-item, it is clearer to see which symptoms are driving the higher total scores, or which items are endorsed less frequently. The item-by-item results can also reveal particular patterns or symptoms of concern. In this study, the item-by-item breakdown of the PHQ-9 revealed a concerning proportion of people having thoughts that they'd be better off dead or of hurting themselves on several days (7.8%), more than half the days (2.6%) or nearly every day (1.9%). When reporting overall prevalence of moderate to severe depression and anxiety been reported, potentially valuable information from individual items is lost.
Second, it is useful to report summary statistics of measures. As displayed in Table 1, the mean and standard deviation have rarely been included in papers reporting population- or community-based PHQ-9 and GAD-7 data. Summary statistics are key results, as they allow straightforward comparison with data from other studies. Further, reporting the minimum and maximum values of total PHQ-9 and GAD-7 scores is helpful in highlighting the range of symptom severity. In this study, the minimum and maximum values in each gender and age category were the same as the range of both measures. This emphasises the representativeness of our sample, as it shows that in each gender and age group, people experiencing the full spectrum of severity of symptoms of depression and anxiety participated.
Third, the prevalence of each symptom severity category of depression and anxiety, from no symptoms to severe symptoms, should be reported. In previous studies that have used the PHQ-9 or GAD-7 to estimate depression or anxiety prevalence in the community or among select populations (Table 1), the prevalence of each symptom category has been inconsistently reported. Often, only the prevalence of clinically significant (moderate-severe) symptoms are reported. Displaying the prevalence of each symptom severity category allows easier and more direct comparison with other research. Further, it provides information about the prevalence of mild or moderate symptoms, rather than just severe symptoms. This is particularly important in COVID-19-related research, such as in this paper, where the whole population has been affected.
Finally, when describing PHQ-9 and GAD-7 results in detail, it is helpful to disaggregate the data by gender and age. The aim of the study was not to test for differences between gender or age groups using bivariate or multivariate analyses. This has been reported elsewhere (Fisher et al., 2020). However, displaying the disaggregated data enables important comparisons between groups. Further, it enables other researchers to make direct comparisons between their data and these results, across gender and age groups.
The detailed PHQ-9 and GAD-7 data reported in this paper provide a useful point of comparison with other population- or community-based mental health research. The COVID-19 pandemic and its implications are unique, and thus, these data may be most suited to comparison with other COVID-19 affected populations, in Australia or elsewhere. We anticipate that these data will also be useful in assessing mental health as populations recover from the pandemic. In addition to COVID-19 research, these data could be used to make comparisons with population mental health in other crises, such as epidemics, natural disasters or conflict. Reporting PHQ-9 and GAD-7 data in detail, particularly item-by-item, has public health and policy implications as well. Item-by-item breakdowns can highlight specific symptoms or areas of concern for the general population, such as a lack of sleep, poor appetite or irritability. These results provide opportunities for policy or public health responses that target specific needs. In conclusion, we encourage future research using the PHQ-9 and/or GAD-7 to be reported in detail, with item-by-item results, summary statistics and all prevalence categories, to enable straightforward and accurate comparisons.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
CRediT authorship contribution statement
Ruby Stocker: Conceptualization, Investigation, Writing - original draft. Thach Tran: Methodology, Formal analysis, Investigation, Writing - review & editing. Karin Hammarberg: Conceptualization, Writing - review & editing. Hau Nguyen: Formal analysis, Data curation. Heather Rowe: Writing - review & editing. Jane Fisher: Conceptualization, Investigation, Writing - review & editing, Supervision.
Declaration of Competing Interest
The authors declare that there are no conflicts of interest.
Acknowledgements
This research was supported by a generous philanthropic donation from Professor John McBain and Dr Penny Foster. The authors are very grateful to the 13,829 people in Australia who kindly contributed by completing the survey. JF is supported by the Finkel Professorial Fellowship, funded by the Finkel Family Foundation. TT is supported by a Monash University Strategic Bridging Fellowship. The Monash COVID-19 Restrictions Research Group includes Jane Fisher, Thach Tran, Karin Hammarberg, Jayagowri Sastry, Hau Nguyen, Heather Rowe, Sally Popplestone, Ruby Stocker, Claire Stubber and Maggie Kirkman (Global and Women's Health, School of Public Health and Preventive Medicine, Monash University).
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