Background
Methods
Literature search strategy
Eligibility criteria
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Type of study: Only epidemiological trials with original data, published in English or German as full articles in peer-reviewed journals were included. Reviews, study protocols, expert statements, diagnostic or methodological pieces were all excluded.
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Diagnostic criteria: Only studies that defined subthreshold GAD by relaxing one or more of the diagnostic criteria from the standardized diagnostic manuals (DSM-III-R, DSM-IV or ICD-10) were included. Papers that used earlier versions of the DSM or ICD were excluded, because of widely deviating threshold definitions for GAD.
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Study samples: Only studies representative of the general population (including sub-populations of several age groups), or of specific patient populations (e.g. primary care or psychiatry), were included. Studies that treated subthreshold GAD as a comorbid symptom of other physical or mental disorders were excluded. Where two or more articles reported data from the same study sample, only the most relevant article was considered.
Data extraction
Assessment of methodical quality
Data analysis
Results
Search results
Study characteristics
Source | Setting | Study period | Study design | Sample size (n) | Age range | Assessment of GAD | Definition of subthreshold GAD | Main findings |
---|---|---|---|---|---|---|---|---|
Angst, 2006 [43] | General population (Switzerland | ZCS) | 1979-1999 | Longitudinal | 591 | 19–41 | Interview (SPIKE) | DSM-III-R diagnosis of GAD with relaxed duration criterion (1 versus 3 months of duration) | - Point prevalence of SUB GAD = 6.2% for 3-month GAD/7.7% for 1-month GAD |
- High levels of distress, social and work impairment & comparable comorbidity rates and suicide attempts in all SUB GAD groups (sign. differences compared to controls, but no sign. differences compared to 6-month GAD) | ||||||||
- Same age of onset, course, and treatment rates in SUB GAD and GAD cases | ||||||||
- 57.5% of treated patients had SUB DSM-III-R GAD & 50% had SUB DSM-IV GAD | ||||||||
Beesdo, 2009 [44] | General population (Germany | GHS) | 1998-1999 | Cross-sectional | 4181 | 18–65 | Interview (CIDI) | Anxious worrying for at least 3 months with at least 2 of the other DSM-IV criteria for GAD | - Higher associations between GAD, also on the SUB level, and medically unexplained pain compared to other anxiety disorders (independent from comorbid depression) |
- Lowest quality of life, greatest disability and health care utilization in the group with both unexplained pain and (SUB) GAD | ||||||||
Bienvenu, 1998 [45] | General population (United States | ECA) | 1993 | Cross-sectional | 1920 | ≥27 | Interview (DIS) | Group 1: DSM-III-R GAD with duration of 1–6 month / Group 2: DSM-III-R GAD of 1–6 month + fewer than 6 associated symptoms | - Lifetime prevalence of SUB GAD = 8% for group 1/12% for group 2 |
- Higher SUB GAD prevalence in women and younger adults | ||||||||
Carter, 2001 [46] | General population (Germany | GHS) | 1998-1999 | Cross-sectional | 4181 | 18–65 | Interview (CIDI) | Persistent worrying for at least 3 months with at least 2 of the other DSM-IV criteria for GAD | - 12-month prevalence of SUB GAD = 2.1% |
- Higher prevalence in women and in older adults | ||||||||
- High levels of distress and impairment in younger and older SUB GAD cases | ||||||||
- Same comorbidity rates in SUB GAD and threshold GAD (commonly occurring: other anxiety disorders, depression, and somatoform disorders) | ||||||||
Grenier, 2011 [47] | Community-dwelling older adults (Canada|ESA) | 2005-2006 | Cross-sectional | 2784 | ≥65 | Interview (ESA-Q) | Symptoms of anxiety, not meeting all symptom criteria of DSM-IV GAD | - 12-month prevalence of SUB GAD = 3.0% |
- Chronic physical health problems, social disability, use of benzodiazepines and comorbid depression not sign. different between SUB GAD and threshold GAD, but sign. higher in SUB GAD than in controls | ||||||||
Heun, 2000 [48] | Older adults (Germany) | 1993-1994 | Cross-sectional | 287 | ≥60 | Interview (CIDI) | DSM-II-R GAD of 6 months, but fewer than 6 associated symptoms | - Lifetime prevalence of SUB GAD = 5.2% |
- Higher SUB GAD prevalence in women | ||||||||
Hoyer, 2002 [49] | Young women, (Germany|DPS) | 1996-1997 | Cross-sectional | 2064 | 18–25 | Interview (ADIS) | Fulfilling 3 out of 4 DSM-IV criteria for GAD | - Point prevalence of SUB GAD = 2.4% |
- 42% of the SUB GAD cases have other comorbid mental disorders | ||||||||
- Sign. reduced psychosocial functioning in SUB GAD cases compared to controls | ||||||||
Kertz, 2011 [50] | Primary care patients (United States) | NR | Cross-sectional | 329 | 22–88 | Interview (PRIME-MD) | GAD symptoms fulfilling DSM-IV criterion A in addition to 1 or 2 of the other GAD criteria | - Point prevalence of SUB GAD = 6% |
- Point prevalence of GAD symptoms = 24% | ||||||||
- SUB GAD as risk factor for threshold GAD | ||||||||
- Sign. poorer physical health, greater stress and sleep difficulty in SUB GAD than in the no worry group; but no sign. differences between GAD, SUB GAD and no worry group on health care utilization and work productivity | ||||||||
Kessler, 2005 [51] | General population (United States|NCS-R) | 2001-2003 | Cross-sectional | 9282 | ≥18 | Interview (CIDI, SCID) | DSM-IV diagnosis of GAD with relaxed duration criterion (1 versus 3 months of duration) | - Point prevalence of SUB GAD = 2.1% for 3-month GAD / 2.6% for 1-month GAD |
- 12-month prevalence of SUB GAD = 3.9% for 3-month GAD / 5.5% for 1-month GAD | ||||||||
- Lifetime prevalence of SUB GAD = 8% for 3-month GAD / 12.7% for 1-month GAD | ||||||||
- Onset, persistence, comorbidity, social and work impairment not greatly different between 1–5 months GAD and over 6 months GAD | ||||||||
- Short SUB GAD episodes typically recur over years | ||||||||
Maier, 2000 [52] | Primary care patients (Cross-cultural|PPGHC) | 1991-1992 | Longitudinal | 5604 | 15–65 | Interview (CIDI) | All ICD-10 GAD symptom criteria, but relaxed time criterion (<1 versus 1–6 months of duration) | - Not sign. smaller psychosocial disability for SUB GAD with 1–6 months (24.3%) and with GAD over 6 month (24.9%), a little smaller in <1 month SUB GAD (17.3%), higher than in those with chronic somatic diseases (19.5%) |
- Higher disability in (SUB) GAD with other comorbid psychiatric syndromes | ||||||||
Olfson, 1996 [53] | Primary care patients (United States|SDDS-PC) | 1994 | Cross-sectional | 1001 | 35–65 | Interview (SCID) | Excessive anxiety for the past 6 months, not meeting full DSM-III-R criteria for GAD | - Point prevalence of SUB GAD = 6.6% |
- Higher prevalence in younger adults | ||||||||
- 48.5% met criteria for another mental disorder | ||||||||
- After adjustment for covariates, no more differences on work, family, social function, and health care utilization in SUB GAD compared to controls | ||||||||
Potvin, 2011 [54] | Community-dwelling older adults (Canada|ESA) | 2005-2006 | Cross-sectional | 2414 | 65–96 | Interview (ESA-Q) | At least 1 essential symptom of a DSM-IV GAD without fulfilling all criteria | - In men, global cognitive impairment is sign. linked to SUB GAD whether depression was comorbid or not |
Rucci, 2003 [55] | Primary care patients (Italy|PPGHC + BS) | 1991-1992 | Cross-sectional | 554 | 15–65 | Interview (CIDI) | 3+ ICD-10 GAD criteria of 1-month duration including apprehension, motor tension, and automatic overactivity | - Point prevalence of SUB GAD = 8.3% |
- Higher SUB GAD prevalence in women | ||||||||
- (SUB) GAD and depression were the most frequent disorders | ||||||||
- SUB GAD as a precursor of threshold GAD | ||||||||
- Poorer health perception and higher psychological distress in SUB GAD than in controls, but no sign. differences in physical disability | ||||||||
Ruscio, 2007 [56] | General population (United States|NCS-R) | 2001-2003 | Cross-sectional | 5692 | ≥18 | Interview (CIDI, SCID) | DSM-IV symptom criteria for GAD, relaxed duration of 1+ months, also non-excessive worry, and only 2+ criterion C symptoms | - 12-month prevalence of SUB GAD = 6.6% |
- Lifetime prevalence of SUB GAD = 13.7% | ||||||||
- Risk of comorbid psychiatric disorders equal for GAD (92.1%) and SUB GAD (86.3%) | ||||||||
- Sign. risk of onset of various comorbid anxiety & mood disorders caused by SUB GAD | ||||||||
Szadoczky, 2004 [57] | Primary care patients (Hungary) | 1998-1999 | Cross-sectional | 1815 | 18–65 | Interview (DIS) | 1 to 5 symptoms of DSM-III-R GAD and duration of less than 6 months | - Point prevalence of SUB GAD = 5.7% |
- 12-month prevalence of SUB GAD = 10.9% | ||||||||
- Higher SUB GAD prevalence in women | ||||||||
Weiller, 1998 [58] | Primary care patients (Europe|PPGHC) | 1991-1992 | Cross-sectional | 1973 | ≤65 | Interview (CIDI) | 4+ symptoms of ICD-10 GAD with 1 automatic arousal symptom, 3–6 months or all ICD-10 criteria, but no automatic arousal symptom or all ICD-10 criteria, but <4 symptoms | - Point prevalence of SUB GAD = 4.1% |
- Sign. poorer overall health status and higher psychosocial disability in SUB GAD patients than in controls, and no differences between GAD and SUB GAD | ||||||||
- Sign. more general practitioner visits for psychological problems in SUB GAD than controls (but no more anxiolytics or antidepressants in adjusted statistics) | ||||||||
- 39% of SUB GAD an 33% of GAD cases were identified as clinical relevant | ||||||||
Wetherell, 2003 [59] | Older adults (United States) | NR | Cross-sectional | 90 | 55–88 | Interview (ADIS) | Anxiety symptoms, not meeting criteria for DSM-IV GAD | - Sign. more sleep disturbance, fatigue, distress/impairment, higher history of psychotherapy, history and current medication use (antidepressants + benzodiazepines) in GAD and SUB GAD than in controls |
- Current psychotropic medication use in 54.5% of SUB GAD (vs. 6.3% in controls) | ||||||||
Wittchen, 2002 [60] | Primary care patients (Germany) | 2000 | Cross-sectional | 17739 | ≥16 | Questionnaire (GAS-Q) | Full DSM-IV GAD, but of 1–6 months of duration | - Point prevalence of SUB GAD = 1.3% |
- Point prevalence of GAD symptoms = 21.7% | ||||||||
- Higher point prevalence in women | ||||||||
- No sign. differences between SUB GAD and GAD on onset, course, and disability |
Study quality
Criterion | Unbiased random population sample | Adequate sample size (>1000) | Adequate response rate (>70%) | Analysis of non-respondents | Reliable and valid assessment of GAD | Total quality score (max. 5) |
---|---|---|---|---|---|---|
Angst, 2006 [43] | 1 | 1a
| 0b
| 1b
| 1 | 4 |
Beesdo, 2009 [44] | 1 | 1 | 1 | 1e
| 1 | 5 |
Bienvenu, 1998 [45] | 1 | 1 | 0 | 1c
| 1 | 4 |
Carter, 2001 [46] | 1 | 1 | 1 | 1 | 1 | 5 |
Grenier, 2011 [47] | 1 | 1 | 0 | 0 | 1 | 3 |
Heun, 2000 [48] | 0 | 0 | 0 | 1d
| 1 | 2 |
Hoyer, 2002 [49] | 1 | 1 | 0 | 0 | 1 | 3 |
Kertz, 2011 [50] | 0 | 0 | 0 | 1 | 1 | 2 |
Kessler, 2005 [51] | 1 | 1 | 1 | 1f
| 1 | 5 |
Maier, 2000 [52] | 1g
| 1g
| 1g
| 0g
| 1 | 4 |
Olfson, 1996 [53] | 1 | 1 | 0 | 1 | 1 | 4 |
Potvin, 2011 [54] | 1 | 1 | 1 | 1 | 1 | 5 |
Rucci, 2003 [55] | 1 | 0 | 0 | 1 | 1 | 3 |
Ruscio, 2007 [56] | 1 | 1 | 1 | 1f
| 1 | 5 |
Szadoczky, 2004 [57] | 1 | 1 | 1 | 0 | 1 | 4 |
Weiller, 1998 [58] | 1 | 1 | 0 | 0 | 1 | 3 |
Wetherell, 2003 [59] | 0 | 0 | 0 | 0 | 1 | 1 |
Wittchen, 2002 [60] | 1 | 1 | 1 | 1 | 0 | 4 |
Study results
Prevalence estimates
Point prevalence | 12-month prevalence | Lifetime prevalence | |
---|---|---|---|
General population | 4.4% (N = 2) | 3.9% (N = 4) | 12% (N = 3) |
Adolescents | 2.4% (N = 1) | n/a | n/a |
Older adults | n/a | 3% (N = 1) | 5.2% (N = 1) |
Primary care patients | 5.9% (N = 6) | 10.9% (N = 1) | n/a |
Point prevalence | 12-month prevalence | Lifetime prevalence | |
---|---|---|---|
SUB GAD of >1-month duration | 5.2% (N = 2) | 6.1% (N = 2) | 12.4% (N = 3) |
SUB GAD of >3-month duration | 4.2% (N = 2) | 3.6% (N = 3) | 8% (N = 1) |